PDA

View Full Version : Homemade quarter-wave ground plane base antenna



mattsowders1989
09-24-2016, 04:33 AM
1.3:1 across all 40 channels. Any Pointers? Its my first build. Any advice would be great. Its about 30Ft in the air
2223

222DBFL
09-24-2016, 11:29 AM
Pic is not showing up Matt. Can you post another?

222DBFL
09-24-2016, 11:30 AM
Never mind it showed up.

222DBFL
09-24-2016, 12:52 PM
Man if you don't have bad weather conditions and wind, a Sirio vector 4000 would work well for you! Mount it about 25-30ft off the ground right where that antenna is now and you will have one nice vertical antenna.
If the one you have up now works, then by all means use it! But be weary of running any power through it just in case. JMHO.

222DBFL
09-25-2016, 06:23 AM
Also a 1:1 matching balun may help you. This will match the impedance if there is any mismatch as your radio wants to not only see a good or decent VSWR reading, but also wants to see the correct impedance, which is 50ohms or near that. 48-52 ohms is a good area. Just some food for thought. The antenna looks good and should work well. Just don't want to see you mess up any of your radios due to impedance mismatch is all. A 1:1 matching balun will help, or slant your radials down more toward a 45 degree angle to the center radial. Again, not trying to tell you what to do, just trying to help is all. I truly hope that the antenna works well. Also you may want to look into building a dipole and hanging it between 2 trees if possible. Get it up to 30ft or more and it will rock!!! But your antenna looks good and should work well for local and DX as well. It's fun building antennas, but you need an antenna analyzer to tune them correctly. Something like an MFJ 269C or similar. Keep at it. And have fun. That is what it's all about!! And. E safe as well!!! Have a good day!!

Jay Mojave
09-25-2016, 02:11 PM
Hello M1989: That 1/4 WL GP Antenna can be adjusted pretty close to a 1 to 1.0 SWR if you wanted. Buy adjusting the vertical radiator and ground plane radials lengths. But 1 to 1.3 coming out of the gates the first time it pretty good!

Using a antenna analyzer to sweep the frequencies will show were the lowest SWR is allowing you to adjust the antennas lengths to were you want it to have the lowest SWR. If the lowest SWR is below CH 1 then its too long, if its above CH 40 then its too short. Somein like that.


The 1 to 1 Balun will not match any impedances, but choke off unwanted coax radiation, but usually not needed on gp antennas. Good going its looking good, and will work well nosing ahead of the non ground plane fiber glass antennas. Hope its not to close the tree's.

Jay in the Great Mojave Desert

222DBFL
09-25-2016, 03:28 PM
Sorry about the post. Jay is correct you have the antenna setup right. No need for a balun unless it's for CMC issues. I see how the radials are now. Took me a bit. Been a long day. Been up with my father since 2am. He has Alzheimer's disease. Like I said, It's been a long day for me!! The antenna looks good Matt and like Jay Mojave stated, a little trimming and you most likely could get a pretty flat or near flat VSWR. Not that a 1.3:1 is shabby by any means! You should be fine with that antenna and the height that it's at!! Have fun with it! And happy DX'ing, what little there is!! Catch it while you can. Been getting a lot of island activity here. Ol Witch Doctor and a few others in the islands have been coming into FL. Some Cali and up north stuff occasionally as well. I have just been sand bagging myself. The locals are back out again here which is a good thing as well. Hopefully you have some locals near you as well. Makes for good times when the DX is dead!! Anyways. The antenna looks good and should work well. Like I said, have fun with it!!! And have a good day. Also thx Jay for making me look again at the antenna, as I was out of it most of the day. I see now what I missed!! Hope all is well your way.
222 Daytona Beach, FL
saying 73 and God Bless.

BOOTY MONSTER
09-25-2016, 10:34 PM
used a PVC X for the standoffs on my 1/4 wave and my first 5/8 wave antenna ...... simple and very effective . nice looking homebrew you got there .

222DBFL
09-26-2016, 04:36 AM
How's it going BOOTY MONSTER. Been a while since I have seen you around or even spoken with you. Hope all is well and thx for responding. You know way way more than I do about antennas!!! That I know is a fact!!
I am using the Sirio vector 4000 with a couple of simple mods I did to it and it has held up through a pretty rough summer here around central FL. It's one heck of a vertical antenna. But that is JMO. I know many say they are weak. And I would have to agree, they could use some modding in specific places to strengthen them up. But other than that they are a great vertical antenna IMO. What's your take on them?? Just curious.

Jay Mojave
09-26-2016, 08:15 AM
Hello All: Gee whiz I left some stuff out there, probably too early with out coffee.....

The Balun doesn't usually need to be on ground plane antenna, but there are designs that may need a Balun, but I have not done a lot of testing on this. I have seen beam antennas work well without a Balun with direct feed. Then using a different length of coax on the same beam antenna NOT work at all, and had to install the 1 to 1 Balun. What I suspect is different lengths of coax may cause this. But need more testing. But its always a good call to use a Balun for the direct feed beam and dipole antennas.

Hope the best for your family.

I have reinforced the Sigma 4 antennas with internal tubing, especially at the base of the antenna were all the stress is, yeah it was slightly heaver but way more stronger. Also replaced the bottom 1 1/2 inch diameter tubing with Aluminum Pipe with a .120 inch wall thickness, and other internal reinforcements. And it survived the strong and constant Santa Ana winds over the years we have here in the Mojave Desert.

Jay in the Great Mojave Desert

mattsowders1989
09-26-2016, 10:06 AM
Thanks for all of the info guys!!!! I will tinker and post my results!!!


Sent from my iPhone using Tapatalk

222DBFL
09-26-2016, 11:27 AM
I love my vector 4K Jay! It absolutely rocks for what it is! I did some minor mods to mine and it appears to be holding up well in the FL weather. And as far as performance goes, it's a great antenna IMO. Others may say different. But hey we all have our own likes and dislikes about antennas. As far as baluns are concerned, I tried one on my vector 4000 and it didn't work well. Took it off and with an analyzer was able to get a flat match. R=50, X=0, VSWR= 1:1. Not too shabby!! And it does a darn good job for me.

Jay Mojave
09-27-2016, 09:24 AM
Hello 222DBFL: I have owned and modified several of the Sigma 4 antennas but not the foreign Vector 4000 antennas, which I hear needs internal reinforcement. I helped install a French Made Sigma 4 Look a like antenna many years ago, for a blind friend. After a light wind it was permanently left as to look blown over at a terrible angle. Replaced it with a used Penetrator 500 antenna that I had in a pile in the back yard. Friends have asked for their Sigma 4 antennas to be reinforced and modified, when time allows.


The thing I have been trying to say here about the 1 to 1 Current Balun is yeah its not a impedance matching device, but converts unbalance to balanced currents, and chokes off currents trying to travel down the outside of the coax. But it has been interpreted as a impedance matching device due to its being installed on balanced antennas ( Yagi Quad and Diploe type antennas ) and making it work much better, bring the low SWR frequency in place and lowering the measured SWR. All due to proper RF Energy feeding the balance antenna properly. Wow my key board it getting hot...

Jay in the Great Mojave Desert

222DBFL
09-27-2016, 10:00 PM
I did mod my vector 4000 a little. Nothing special. Just added about 8" or so of HD heat shrink to every joint from top to the bottom, and also instead of side mounting it to my mast, I slid it down over my mast pipe so as it's not off to the side. Less stress on the antenna I believe. This coupled with adding many Dacron and paracord ropes at about 8ft from the base of the antenna has helped tremendously. It's seen some nasty weather and some darn good wind gusts this past summer and it still looks like new. I did also take the time to use NO-OX on the entire antenna as well. Just a very light coat on the entire thing, this does nothing for strength, but has kept any corrosion from happening. Like I said, the antenna still looks pretty new as far as I can tell. I used good coax, Andrew LMR400 and also wether proofed it the right way. And I have had zero issues with it. It's been up for about 2 years now which isn't very long to some, but I promise it has seen its share of bad weather and I even thought a few times that it would be destroyed. Not the case. It has held up great and continues to make me contacts both locally and out in DX land. Anyways, just my experience with the Sirio vector 4000. Yes it can use some modding and could definitely be beefed up, but for what it is, it has been one heck of a good vertical antenna for me anyways. Thanks for all the responses and also pointing out the balun deal. I always am learning and that is what keeps me going!! Again, thx[emoji106][emoji106].
73 to you and yours and God Bless from 222 Daytona Bch., FL.
Sean.

BOOTY MONSTER
09-30-2016, 11:38 AM
How's it going BOOTY MONSTER. Been a while since I have seen you around or even spoken with you. Hope all is well and thx for responding. You know way way more than I do about antennas!!! That I know is a fact!!
I am using the Sirio vector 4000 with a couple of simple mods I did to it and it has held up through a pretty rough summer here around central FL. It's one heck of a vertical antenna. But that is JMO. I know many say they are weak. And I would have to agree, they could use some modding in specific places to strengthen them up. But other than that they are a great vertical antenna IMO. What's your take on them?? Just curious.

i'm doing very well , thanks for asking . hope you are also . had my gastric bypass in april 2015 and i'm in the 230's now and hope to stay under 250 . had my knee replaced 3 months ago and that has gone very very well ! so i'm doing really great !


i'm a huge fan of the vector 4000 type antennas . i was so concerned about the durability of it's construction , there were many comments about it flailing in winds and breaking so i decided to try to build my own and it is a beast physically ! electrically it should be the same potential as you'rs or any other antenna of this design . i built a few dipoles , 1/4 wave ground planes , a few variations of 5/8 -.64 wavelength antennas and this vector did perform better , not night and day but better . haven't had it up for a few years , but i'm keeping it because i hope to get back up at some point . here's a link to my build ......

http://www.cbjunkies.com/threads/66-home-brew-sigma-4-vector-4000

222DBFL
09-30-2016, 07:48 PM
Love my vector 4000. It has done me well for the past couple years!! And with some simple mods it has stood up to some nasty storms. I live in Central FL and we have had our share of crappy weather this past summer. I didn't build mine like yours is, but some simple mods like HD heat shrink on every joint from top to bottom and also mounting it not onto the side of my mast pipe but down over it making it straight instead of adding
more pressure to mount it has done an excellent job. Yes I though very much that it would fail, but be darned if it doesn't take a licking and keep on ticking! Just like a timex LOL!! Anyhow, glad to hear you are well and that your health is getting better!! Not many understand I suppose bow well the Sirio vector 4000 can work if you take the time to do some simple things to sturdy it up. I also used NO-OX on the entire antenna minus the SO-239. This has kept it nice and shiny and looking like new for a while now. Little things do help and I am happy to have one of these antennas. They rock and man will they put out a signal and receive one as well! With mine only being 27ft to the base. I am able to Talk out to about 70 miles consistently locally and at times double that! Not shabbby for only being as high as it is off the ground to the base (27ft). Anyhow m, glad to see I'm not the only one that thinks they are a good antenna. Wish I had the skills like you to build one like you did. But I am happy with what i have. Anyhow. Again, glad to hear you are doing better and hope to one day catch you on air!!
222 Daytona Beach, FL saying 73 and God Bless.
Sean.

mattsowders1989
10-04-2016, 04:38 PM
Hey 222,
I'm worried about VSWR now that you have mentioned it. I have a drake MN2700 that has a 10 meter position. I have tried to look up online on how to use it and what to do but I can't find anything helping me with 11 meter. I'm somewhat new with the CB world and just need some help.


Sent from my iPhone using Tapatalk

mattsowders1989
10-04-2016, 04:50 PM
This is what i have:

2226

mattsowders1989
10-04-2016, 04:52 PM
sorry that its upside down

222DBFL
10-04-2016, 09:01 PM
Give me some time on this one Matt. I am currently trying to get all my ducks in a row due to the hurricane that is about to hit us around Daytona Beach, FL, where I live only about 3-4 miles from the coast. So I apologize if I don't respond back sooner. I just have too much going on at the moment. Hopefully Crusher or BOOTY MONSTER will see the post and be able to help sooner than I can. I'll have to do some research on that amp to see if it's capable of being used on 11 meters. It most likely is, but you don't want to take any chances. Like o said, give me a few days as I am running around like a chicken with its head cut off trying to make sure my antenna and all other stuff around my house will survive if we get a direct or near direct hit which seems pretty imminent at the moment!! Wish me luck!!!

mattsowders1989
10-04-2016, 09:48 PM
Oh ok. Good luck buddy. Hope you don't get any damage.


Sent from my iPhone using Tapatalk

mattsowders1989
10-04-2016, 09:50 PM
Btw, it's an antenna tuner. Not an amp. At least I think it is. I do know that it isn't an amp.


Sent from my iPhone using Tapatalk

222DBFL
10-05-2016, 04:49 AM
You are right. Maybe if I took my head out of my ass I would have noticed that LOL!! That is a nice one actually and should work on 11 meters. Best way to try is to place it in line after the amp if will handle the power. Then place it on 10m and tune the 2 knobs for lowest VSWR with a decent carrier on AM. Using a little more than 4 watts may be the way to go as well as you normally don't see some issues until power is applied. If you can get your amp to key up around 20-30 watts of carrier on AM mode, try tuning it on the 10m setting, first tune the left knob then the right one. Might work. Also for first time testing use only your radio as to not blow anything up!! If possible use the cheapest radio you have on hand just in case!! JMHO's. Like I said it would take me som time to look more into that particular unit as my mind is elsewhere at the moment. Worried about my house and antenna as well as we live about 3-4 miles max from the coast!! So we are going to get pummeled if this storm moves any more west than it has already. Wish I didn't have to work today so I could focus more on my house and getting my mast lowered down, but to get it lowered isn't an easy job due to coax being taped to the mast, and isolated with 1/2" coax grommets. And also the bolts that need to be pulled as well as hose clamps snd such!! Not an easy 5 min job unfortunately!! Anyways, I'll get back to you as soon as I can! Until then try what I said and see if you can get it to work properly. If it works you should be able to tune the VSWR to 1:1.

mattsowders1989
10-05-2016, 08:15 AM
Ok. Thank you very much. I will try that as soon as I get off work and I will post you my results. I'll wait on your reply as well. I hope you don't get hit too hard from hurricane Matthew.


Sent from my iPhone using Tapatalk

222DBFL
10-06-2016, 03:46 AM
Here is the manual for the unit you have in the pics Matt.
http://www.qsl.net/ea4bb/EA4BB/Old_Radios_files/MN2700.pdf

222DBFL
10-06-2016, 03:48 AM
It's a link to the instruction manual. Save it to your computer or phone. It should explain what you need to know and I will also keep looking into whether it's useable on 11m or not.

222DBFL
10-06-2016, 04:52 AM
First off. Sorry for the long post but there is a lot of good info.

From what I have quickly read, this unit came with an optional 4:1 balun as well, accessory model #B1000.
Here is the description from eham.com

Description: Drake MN-2700 with optional accessory B-1000 Balun. Quality as usual from RL Drake. No complaints. I prefer it over the roller inductor tuners (fast QSY). Accurate wattmeter/SWR bridge and ability to match a wide variety of antennas. Once common at Hamfests and in the Yellow Sheets, they are now "locked" in the custody of their current owners who will probably never part with them. I saw this coming, so I acquired a mint one with B-1000 Balun for my long term collection. Unsung hero. Havent seen one on Ebay in over 6 months. Optional B-1000 Balun known to easily command $100.
Also from reading i have seen many saying it doesn't work too well with 50 ohms antennas. It's more for a long wire. Also have a look at the frequency range listed in the photo I took. Appears it doesn't cover 11 meters or 27mhz area.

http://uploads.tapatalk-cdn.com/20161006/b81ac93a3d05a871a0c44d4b159e3682.png

Like I said before, you can try to use it on 11 meters and see what you get. If your VSWR is reading below 1.5:1, I would not even worry about using it. That is JMHO. It's a good unit, but without the accessory B1000 4:1 balun and also knowing it might not work too well on 11 meters if at all, you may want to place it to the side until you decide if you want to get your amateur radio license. But hey it's worth a shot at least to try it with just a radio and a known antenna with a bad match. This includes impedance as well as VSWR. Read the manual and get an understanding of how to use it and go from there. Just be careful and don't use a radio you much invested into. A cheap CB radio will work fine.
Just something to think about here, maybe sell the unit and put the money toward an antenna analyzer. Then you can tune antennas the correct way. The MFJ269C or the rig expert aa-30 antennas analyzers are what you want to look into getting. The rig expert I believe is a better analyzer, but the MFJ269C might be easier to use.
And to properly tune an antenna with the above analyzers you will need to cut an electrically tuned 1/2 wave coax jumper cut to your desired frequency. Here is the formula for making one. Also you don't need to have an antenna analyzer to perform tuning. You can use a known good SWR meter. But you need to make sure to use a 1/2 wave electrically tuned coax from the radio to the SWR meter and from the SWR meter to the antenna. This keeps everything in 1/2 wave increments or multiples of it. Hope all this makes sense. Read on down as it explains more in detail as to how to make this coax jumper and why. If this is a magnet mount antenna for your vehicle, use a 12" or shorter jumper from the radio to your SWR meter, then connect the coax from the magnet mount to the antenna port of your meter. If you use an antenna like the Wilson 1000 or Sirio 5000 performer, they are already most likely matched or closely matched to 50 ohms. That is what the loading coil is for. It a matching network basically. And you want the tallest antenna you can get as well for a mobile or one as close to 108" as possible. The Sirio performer trucker series antenna is about the longest one I have seen. They are longer then he Wilson antennas and much longer than the k40 antennas. Again. This is for a mobile install. For a base station install follow the directions below and you should be good to go. Once you have tuned the antenna with the 1/2 wave electrically tuned coax jumper or jumpers, you can then use whatever length you want. Whatever will reach from point A to B and leave a bit of extra coax for just in case you get a bad connector or if your coax gets kinked or gets water intrusion or some other issue, but try not to leave too much extra as this can but more then you truly need as you can get issues like common mode currents along the coax of its too long. Again, not trying to confuse you, just want to give you as much information as possible! Below is a chart for part of the formula that requires you know the velocity factor or VF of your coax.
Some coax companies like Times Microwave or Andrew, and most other quality coax companies will list the velocity factor for their coax as well. Below are just some common numbers. But you will find that different coax may have a different VF then the ones listed below. Like Andrew/Commscope LMR400 type coax has a VF of 85%. That is faster than anything listed below. So make sure you use the correct VF when making your coax jumpers.
Here are the velocity factors of the various Belden coaxial cables:

RG-59 .66
RG-59/U (foam) .79
RG-8 .66
RG-8/U (foam) .80

Here is how to figure out your true 1/2-wave:

492 x (Velocity Factor) / Frequency (MHz)

For example, I want to figure out the true half wave coax length for RG-59/U (foam) on my home channel (ch. 33 - 27.335):

492 x .79 / 27.335 = 14.22 feet

Now add 14.22 to itself to determine your 1/2 wave multiples. Remember to use every other number. See the example below:

14.22 feet 1/2-wave multiple

28.44 feet 1-wave multiple

42.66 feet 1/2-wave multiple

56.88 feet 1-wave multiple

71.10 feet 1/2-wave multiple

85.32 feet 1-wave multiple

and so on . . . .

Use only the lengths that fall on the 1/2-wave multiples and you will be all set.

Now in order to get the true SWR of the system, you have to throw away that 3-foot jumper cable for now. The SWR meter has to fall on a 1/2-wave point on the coax run. Using the example above, you need a 14.22 foot jumper from the radio to the SWR meter, and a 1/2-wave multiple length from the SWR meter to the antenna. If my antenna is 65 feet away from my radio, I need a 14.22 foot jumper from the radio to the antenna, and a 71.10 foot length between the SWR meter and the antenna.

Further Considerations

Now that we've said all this, we should discuss the trade-offs between having the perfect lengths of coax vs. having the shortest possible run for efficiency purposes. If it is possible to test the SWR while the antenna is installed, by all means do so. After you have your match as flat as possible, reduce the coax length to the shortest possible run. Your SWR will remain the same as far as the antenna is concerned and you may reduce the overall length of your coax enough to add more efficiency to the overall system. Experiment with this and have fun!

I hope that this will help you well. Have a good one. Bracing for a bad situation here!! Going to be nasty as all get out and hopefully my Antenna will survive all the crap that is coming. My fingers are crossed and I added extra guyed ropes and ratchet straps to my mast pipe just about 5ft from the base of the antenna. Best I can do is to also lower the antenna 10ft, but I am still worried like heck! Anyhow, have a good one and again. I hope all is well up toward your way!!
73 and God Bless
Sean.

mattsowders1989
10-06-2016, 08:33 AM
Thanks Sean for all of the useful info! I will work on that this weekend. I will have to lower my antenna down (witch is the homebrew I made) and take the coax off to measure. Once i get that done, I will post what I have got from it all.

mattsowders1989
10-07-2016, 05:51 PM
What about the cable between my radio and amp? Does it need to fall in that 1/2 wave?

mattsowders1989
10-07-2016, 06:02 PM
also. the biggest problem i am running into currently is the antenna warning light on my radio when i have my transistor amp on high. on high that amp puts out about 150 watts. My standing wave is 1.2:1. it is really aggravating me. i know my vertical element and radials are the right lengths. im using the homebrew antenna that i originally started this post with.

mattsowders1989
10-07-2016, 06:04 PM
the coax i use is R & L Electronics RG 8/U .80 2015 Low Loss.

mattsowders1989
10-07-2016, 09:12 PM
Better yet, what is the best, cheapest thing I can do about my coax and antenna? I have next to no money I can spend. If I knew what I had to do exactly to make what I have work correctly, I would do it. The Drake matching network just won't work with 11-meters. I've measured my coax and have it the correct length. Maybe my radials aren't at the right angle? I know they are close to a 45 degree angle. It's just very aggravating because one, I have taken so much of your time, Sean, and two, I've put a lot of work into my base setup. I just want it to work right.


Sent from my iPhone using Tapatalk

mattsowders1989
10-07-2016, 09:13 PM
I had already downloaded a manual for the Drake unit, I just needed some radio expertise


Sent from my iPhone using Tapatalk

222DBFL
10-07-2016, 10:20 PM
Try a 1:1 matching balun at the feedpoint of your antenna as your VSWR might be good but your impedance might be out of whack and not near 50 ohms as it should be. Also a 1:1 balun will help with any CMC issues that may be present on the coax. And also always measure the VSWR without the amp in line. There is more to tuning an antenna than just VSWR. Impedance, resistance, and reactance as well as VSWR all need to be good. Impedance matching is just as important as VSWR. As I said your VSWR may be good but is it at or near 50 ohms. This is where an antenna analyzer helps a bunch!! But a 1:1 matching balun may help this issue. And no your amp coax jumper should not have to be a 1/2 wave length. Make it reach from amp to radio. If it's bad when the amp is off, you most likely have other issues. Like CMC along the coax or an input/output issue with the amp with impedance being mismatched creating a bad VSWR. Get a 1:1 balun and try that. Or some snap on ferrite chokes, read up on the use of them as well as the 1:1 balun. You might be able to make a coil choke with your coax as well sand help. Read up on how to match impedance. And now it correlates with the VSWR readings you see now. I am down and out for now as it got pretty bad here with the hurricane that went through!! Man we got worked!!! Anyhow,'try to study some of the info I have given you. And have a good one!!

mattsowders1989
10-10-2016, 11:43 AM
Ok. Thank you sir.


Sent from my iPhone using Tapatalk

mattsowders1989
10-10-2016, 08:24 PM
I hope your equipment didnt get too damaged!

222DBFL
10-11-2016, 01:57 AM
Damage is not bad. Antenna is bent a little from a fast take down. But it can be fixed or replaced. Other than that I have all my radio and other equipment still. Will rebuild. Just takes time to do it correctly. Going to be using LDF4-50A heliax coax this time. A step up from LMR400. Very low loss coax!! And also will be using a different mast/tower system. But I will get it done. No worries!! Might take me a little while. But when I am done it will be a solid setup that should work quite well!!!

mattsowders1989
10-11-2016, 07:18 AM
That's good. I don't have the money yet but I'm going to get an antenna analyzer as soon as I can. I got my SWR down to between 1:1 and 1.1:1. Still getting an antenna warning message on the cobra but that is only with my transistor linear on high putting out 150 watts. I noticed that with this amp I am using, I'm getting a backward swing. I dead key with the amp and 150 watts and when I modulate, it swings to about 130. The radio is a cobra 29 LX. It is factory stock. Never been peaked or anything. Not sure why it's doing that but the locals (about 15 to 20 miles away), tell me I sound crystal clear.


Sent from my iPhone using Tapatalk

JesseJamesDallas
10-11-2016, 07:34 AM
What is your dk on the cobra set at? If it's under 3w that's why you get the antenna warning message... although a backward swing is usually due to a high dk.

mattsowders1989
10-11-2016, 07:53 AM
Dead key is 3 watts. I'm guessing I should back it down to a 1 watt dk?


Sent from my iPhone using Tapatalk

222DBFL
10-11-2016, 08:30 AM
Yep. You most likely don't need 3 watts of dead key. Just like JJD is stating. About 1-2 watts is normally all that is needed. A proper or close as possible ratio of 1:4 power output is what is really needed. So if the amp is producing 150 watts pep then your dead key should be about 30-45 watts. This should help the backwards swing issue. It's not hard to turn down the AM power and achieve what you are looking for. Also you most likely need to adjust the modulation as well. A tech should really perform this work if you don't know what you are doing as you can damage your radio very quickly using the wrong tools!! Use only plastic tip screwdrivers, or something that is electrically non conductive. Ceramic works as well but you have to be careful using a ceramic tipped screwdriver as well due to being able to damage parts in the radio. Like I said. Best bet is to send or take both the amp and radio to a good tech and have them matched up for each other. Or at least have the radio done. A variable power knob can be added or placed where the delta tune is located at now. Don't use the pot with the delta tune on it. Have a proper one placed in its spot. And have the dead key set to be able to go from about .5 watts to 4-5 watts max. This will help with using most any amp you want. Just some food for thought. But at any rate, yes you need to get the dead key dropped down on your radio to at least 2 watts or less. No 2 watts isn't a standard, it's just an approximation of where you need to be. The amp May need as little as .25 watts. Hard to tell without having the amp in front of you and keying into it with a radio that can go that low in power. That is why I said a variable power could or might be a good way for you to go. This way you can run the radio without the amp if you wanted, or use a different amp.

JesseJamesDallas
10-11-2016, 09:15 AM
Yep. I would back off the dk to 2w, that "should" make the amp happy and not swing backwards...however on the Cobra 29 lx and lxle models it will probably cause a RF POWER fail when your in test mode because the radio from the factory was set for 3w...just have to ignore that fail warning.

mattsowders1989
10-12-2016, 12:17 PM
Cool. Thanks guys. You all have been a big help.


Sent from my iPhone using Tapatalk

mattsowders1989
10-12-2016, 12:57 PM
Does how much the radio swings matter or is it mainly the dead key that I should be concerned with?


Sent from my iPhone using Tapatalk

JesseJamesDallas
10-12-2016, 06:27 PM
Does how much the radio swings matter or is it mainly the dead key that I should be concerned with?


Sent from my iPhone using Tapatalk
It can, but unless that Cobra has had some serious mods done to it, it shouldn't mater in your case. I would just deal with the DK.

mattsowders1989
10-12-2016, 06:28 PM
Ok cool. Nope. It's all factory on the cobra.


Sent from my iPhone using Tapatalk

mattsowders1989
10-12-2016, 06:37 PM
I'm going to do some research and see which pot will turn down the dead key


Sent from my iPhone using Tapatalk

JesseJamesDallas
10-12-2016, 07:33 PM
I'm going to do some research and see which pot will turn down the dead key


Sent from my iPhone using Tapatalk
Not real sure, but I don't think there is a pod on the Cobra's, I think you have to add a resistor to lower the dk on the 29's. And if that 29lx has the new SMT board, "good luck"...Those resistors are tiny little critters.

Last 29lx I bought, I got from Bells CB, and just had them install a variable power knob where the Delta Tune was so I could lower the dk down to 1/2w and up to 5w.

mattsowders1989
10-12-2016, 07:58 PM
Well I do have a SMT rework station that I use for laptop and game system boards. I'll do some research and see what I can find out.


Sent from my iPhone using Tapatalk

222DBFL
10-13-2016, 06:12 AM
That is the best way to go JJD. Having variable RF power added. No real need for Delta Tune on an AM only radio especially if it's pretty well on frequency. Have them align radio and add variable power and some other things, and they are great AM radios. My 29lx le has a 1969 final mod done to it. Limiter still intact and it does well. Good audio and works well.

222DBFL
10-13-2016, 06:23 AM
There are plenty of videos showing the mods, but IMO, it's best to send the radio to a good tech and have a tune and alignment done and also have variable RF power installed like JJD has his. Great spot for it as you don't ever really turn the delta tune knob on that radio!! There are a few good techs and out there. Screwdriver at Bells CB, Doug's custom CB, Mikes Radio and Repair, Key CB, and a few others that do a good job and have the proper equipment to do them the correct way!! But if you want to mess with it, just google the mods for a 29lx. There is a bunch of info. Be careful inside the radio! And like I said, if you are serious about messing around for a while in the hobby it's either buy the proper equipment to tune and align a radio or find a good tech and have them do the work. Either way you are going to pay LOL! Not being harsh, just truth is all man!!!! Have a good one and be safe inside that radio if you mess about. No metal screwdrivers!!!

mattsowders1989
10-13-2016, 07:16 AM
It is not SMD inside the radio. I see everything I need to do but I believe I'm going to find a respected tech to do it for me. I've been working with electronics my whole life and as my full time job but I'm 27 years old. I'm a pup. I'm new to the CB world. I'll let someone with my age in experience work on it for me. Thank you both so much for all of the info. My SWR is down to a 1:1. And that's on that home made quarter wave I started this thread with. Thank you both so much!!!


Sent from my iPhone using Tapatalk

222DBFL
10-13-2016, 08:52 AM
Mine isn't either, SMD that is. It sending to a good tech is a good idea. They have the proper equipment on hand like oscilloscopes, signal generators, proper watt meters. And all other equipment and tools necessary to perform a proper tune and alignment and add a variable DK to the radio. And glad to hear you got your antenna tuned well[emoji106][emoji106]. Have fun and enjoy man!!

222DBFL
10-16-2016, 05:17 AM
Also just some food for thought, the uniden 980's are getting cheaper. As in price. You can a new one shipped for about $112 or less if you look around. They are great SSB radios. They aren't bad on AM either. And if I have said it before, I still will say it again, out of the box they are pretty well dead on frequency. And it's not hard to lower the dead key on one either. Just need a 50ohm dummy load and a watt meter capable of handling about 20 watts or so. You can find small dummy loads on eBay for not a lot of money as well. RT206 is the pot that you turn to get your AM carrier down to about 2 watts and then you can adjust the modulation to swing to 8 watts PEP by turning RT205 which is the AMC limiter. Use a plastic tip screw driver or make one out of something. Not hard to adjust these 2 things on this radio. RT203 is for the SSB power or the SSB ALC. You can leave this as is or turn it down slightly to keep the heat down.
I know you are working on your AM radio at the moment. But the uniden 980 can be used for both AM and SSB. Add a decent power mic like an RF Limited 2018 extreme to one of these radios and they kick butt. Clean, clear audio. I believe JJD uses an 880 which is the AM only version of the this radio. He may chime in and give some review of his radio as well. I just know the 980 is a great little radio for the money and there aren't any other new radios in the same price range that offer as much as they do. Again, just some food for thought. Let us know how things are coming along as well. Hope all is well with you and yours and stay safe man.

JesseJamesDallas
10-16-2016, 09:05 AM
I have the Uniden 680...the "runt of the litter". Only reason I bought it, was for it's size...fit real nicely in the dash... and it is a SMD radio, along with the 880 and 980.

mattsowders1989
10-16-2016, 11:31 AM
I know this is going to sound like a stupid question and I apologize for it before hand. I'm some what new to CB so bare with me. Why is it when I role up my excess coax, my SWR is 1:1 but when I stretch it out, it jumps up to a 1.9:1? Seems like I need something to fix that problem. Is it something I can make?


Sent from my iPhone using Tapatalk

222DBFL
10-16-2016, 11:35 AM
Sorry JJD. I knew you had the smaller one, didn't know it was the 680. Let me ask. Performance wise, Good radios?? I am pretty sure I know the answer but it makes it seem less opinionated when more than just one person answers I suppose. Thanks for any and all replies. Just trying to help someone get a decent radio that won't break the bank. I know there are many other radios that I could mention, but most cost double what the 980 does.

JesseJamesDallas
10-16-2016, 11:56 AM
Sorry JJD. I knew you had the smaller one, didn't know it was the 680. Let me ask. Performance wise, Good radios?? I am pretty sure I know the answer but it makes it seem less opinionated when more than just one person answers I suppose. Thanks for any and all replies. Just trying to help someone get a decent radio that won't break the bank. I know there are many other radios that I could mention, but most cost double what the 980 does.
I have the 680 in my Tacoma, and a Uniden 520xl in the Suburban's dash...IMO, the 520 is a better radio...for what they are.

Biggest, (if not the only) problem is channel rejection with these small radios. They just don't have the filtering the larger radios do so if someone with a strong radio is anywhere near you on a different channel, they are going to bleed all over you... Also not much of a swing monster either, but stick something like a 1x2 or 1x4 behind it and they become Audio Monsters! (need a amp with a driving stage since these radios don't have allot of "get-up-and Go")

JesseJamesDallas
10-16-2016, 11:59 AM
I know this is going to sound like a stupid question and I apologize for it before hand. I'm some what new to CB so bare with me. Why is it when I role up my excess coax, my SWR is 1:1 but when I stretch it out, it jumps up to a 1.9:1? Seems like I need something to fix that problem. Is it something I can make?


Sent from my iPhone using Tapatalk
If you have that much extra coax, I would either leave it rolled up, or cut off what is not needed...If you cut it off, you may end up having to re-tune the antenna.

mattsowders1989
10-16-2016, 12:01 PM
Ok. Thanks


Sent from my iPhone using Tapatalk

222DBFL
10-16-2016, 12:37 PM
Leave it coiled up like JJD stated. It may be acting as a choke when you have it rolled up and this isn't necessarily a bad thing. As long as the radio is seeing a good match I would leave it be the way it is coiled up.
And yes JJD, they aren't swing monsters for sure but like you said add a nice 1x2 or even a 1x4 and watch out!! They are clean, clear sounding radios and clean in equals clean out. I've not noticed any channel rejection issues with the 980, but I haven't been close enough to anyone to see if it's an issue with that radio. I know my magnum 257HP and my optima MK3 do have this issue. Way over sensitive receivers. Nice thing about the Icom 746 I have is being able to use NR and the twin PBT as well as the notch filter. Man does it get rid of unwanted crap quick!! But it's an SSB radio and I know that. My cobra 29lx le is a nice radio as far as AM only and with the 1969 final mod does rather well. Someone in TN did the work and I picked it up from a trucker in Michigan while I was working there. Also got a nice predator 10k antenna as well. Use it with a 4 magnet mount on top of an old Nissan Pathfinder with my TNT 600hd from time to time. Gets the job done when I need it to. Anyhow. Enough BS.
Matt I truly hope that you get all your things right and have fun. That is what the hobby is all about man!!

mattsowders1989
10-16-2016, 12:44 PM
Yeah. Thanks 222. Trying to just get everything working right.


Sent from my iPhone using Tapatalk

JAF0
10-16-2016, 05:35 PM
I know this is going to sound like a stupid question and I apologize for it before hand. I'm some what new to CB so bare with me. Why is it when I role up my excess coax, my SWR is 1:1 but when I stretch it out, it jumps up to a 1.9:1? Seems like I need something to fix that problem. Is it something I can make?


Sent from my iPhone using Tapatalk
Mind if I ask what type of coax you're using, and how many feet?

mattsowders1989
10-16-2016, 05:38 PM
the coax i use is R & L Electronics RG 8/U .80 2015 Low Loss.


Sent from my iPhone using Tapatalk

mattsowders1989
10-16-2016, 05:39 PM
About 50 feet


Sent from my iPhone using Tapatalk

JAF0
10-16-2016, 06:01 PM
the coax i use is R & L Electronics RG 8/U .80 2015 Low Loss.


Sent from my iPhone using Tapatalk

80% Velocity Factor RG-8? Usually RG-8 is 66%...???

mattsowders1989
10-16-2016, 06:02 PM
That's how the cable is labeled.


Sent from my iPhone using Tapatalk

JAF0
10-16-2016, 06:18 PM
OK, looks like it's their version of 9913 actually at 84% VF.
Try 7 turns around a 4" former like white or gray PVC right below the feed point of your antenna, (NEVER use black ABS, has a high carbon content, not invisible to RF)

...and if at all possible either elevate both the choke and antenna above the metal mast with several feet of fiberglass, wood, etc.,

or do like Booty did with his Homebrew Sigma-Vector, (which you can see in his picture) where he moved the coax & choke away from the metal of the mast and wrapped quite beautifully off to one side.

(MAJOR KUDOS, BOOTY, I LOVE that design, very clean & effective!)

Installing a CMC (Common Mode Choke) right on or around the metal of the mast defeats the purpose. The RF field continues to flow around the choke via the mast.

Notice how Booty's keeps the coax away from the mast and actually turns the RF field perpendicular (90) to the mast. Perfect!

5.5T on a 4" former for 66%, 7T for 84% has worked well for me in the past.

Then you shouldn't have to coil your coax to fool the SWR.

mattsowders1989
10-16-2016, 06:24 PM
Ah ok. Very useful info. Thank you so much!!!! I will post photos once I get everything lined out.


Sent from my iPhone using Tapatalk

JAF0
10-16-2016, 06:50 PM
...and another thing people will sometimes do is carefully slice away 1/2" of the coax casing just outside of where it goes into the house and carefully solder a short-as-possible ground strap from there to a ground rod, taking care not to melt or deform the dielectric beneath the braided shield, then reseal with "Liquid Electrical Tape" in the can, or self amalgamating or vulcanizing tape.

This helps to shunt to ground any static or stray RF picked up by the shield of the coax, including any RF which may have leaked past the choke.

mattsowders1989
10-17-2016, 05:23 PM
Awesome. Thanks!!!


Sent from my iPhone using Tapatalk

222DBFL
10-19-2016, 05:25 AM
They actually make kits specifically for that JAF0. Depending on coax size they have a copper piece that gets attached to the coax at the either the entry point and/or base of the tower as well as inside shelter or radio room onto ground buss bar. Andrew, Commscope, makes the kits, as well as I am sure other companies do as well. Not sure about a small coax like RG8X. But LMR400 and such and I believe they even make a kit for LMR240. Yes it is just slightly larger than most RG8X. Just slightly!! They may have kits for RG8X, I just don't use that particular coax so I don't truly know. Anyhow, all very good tips!! Have a good one.

mattsowders1989
10-19-2016, 07:18 AM
Well I went out on a limb and installed a swing kit in the radio. After lots of testing, I've found that my dead key at 3/4 watt works best on my amp. At 3/4 watt, I modulate to 5 watts barefoot. I get a real nice swing with the amp, and not backwards! Haha


Sent from my iPhone using Tapatalk

222DBFL
10-19-2016, 01:25 PM
Good deal! Did you happen to use a 50 ohm dummy load when you tuned your dead key and not your radio connected to the antenna but rather the dummy load? Obviously a watt meter was used, but was a 50 ohm dummy load used as this is the proper way to tune a radio as the dummy load will remain a constant VSWR and also impedance and reactance. With your antenna you might see 3/4 watt on channel 1 and 2 watts on channel 40 or vice versa. Just some food for thought. Having a 100 watt 50 ohm dummy load that is of a good make is a great tool to keep on hand when you start messing about with radios as you can check output of other radios and not worry about VSWR issues. Even the paint can dummy loads work well. They are filled with mineral oil I believe. But at any rate, glad to hear you got things working and more of an understanding to what you're accomplishing! Good deal man! Have a good day and be safe!!

mattsowders1989
10-19-2016, 09:11 PM
I used the antenna. Not a dummy load. I just found out that the lower I put my dead key, the bigger a squeal is transmitted, so much it almost takes my audio. Now I'm back to square one. I have my dead key at 3.5 watts and am back to getting a backswing on power meter. The reason I haven't paid someone to do what I want the radio to do is because I don't have any extra money to spend. Plus I want to know how to do whatever I want to do to my radio. I followed a guide on cbtricks specifically for the cobra 29 line of radios with the final that my radio has in it. (2SC2078). I'm confused as to why is seems like the lower wattage I go, the more over driven my audio sounds. I tried bumping my modulation down a bit and it seemed to help a little but not much at all. I've also tried multiple mics. I have also hooked it up in my car witch has a Wilson 500 on top of it. As it sets right now with the amp on, it sounds ok but it still has a big backswing. I have a second transistor amp at the same wattage (150) that I have switched out with as well. The guide to the swing kit I used entails these parts:
Tip120
100 ohm resistor
100uf 16 to 25v capacitor
1k or 5k ohm pot

I did read somewhere about using a 220uf cap I read of the 100uf but I really don't see that fixing my problem. I know I'm a hassle and I apologize in advance.


Sent from my iPhone using Tapatalk

222DBFL
10-20-2016, 04:18 AM
Also before I say anything about needing things, how many amp power supply do you have? And is this same power supply running your radio and amp. The radio won't draw much at all I know that, but your amp may draw up to 20-25 amps and maybe a little more on some voice peaks and depending on mode of operation. If your PS is only rated at 20 amps then it's going to be hard pressed to get all the power that amp might and I say might need at times. Best to have head room when messing with power supplies. For a 2 pill amp like yours it shouldn't draw more than 15-20 amps max. It may just be your PS is not up to the task. Most PS amperage ratings aren't the most accurate!! Something like a 30 amp power supply is what I would use, or more amperage. Between radio and amp and anything else you have on that circuit that that PS is plugged into, you may not be getting enough power to the entire system under a load. I don't know what you are using for a power supply so it's hard for me to know. I use one of the MegaWatt power supplies, the S400-12, I have it set at 14.0vdc and it operates at 33A at 100% duty cycle and up to 40 amps I think for short periods of time. It's a small switching power supply but they are clean and don't produce any hash!! Anyways, I have run a 2 transistor amp on it and that amp has toshiba 2879's in it. I only used my uniden 980 to drive the amp, but was able to get 200 watts on SSB just fine with about 10 watts of pep input. Dead key on that radio into the amp was set at 2 watts dead key and 8 watts of pep swing on AM, and 10 watts of pep power on SSB. I don't have a true peak reading meter but if you take your time you get decent at just performing little things. I don't make the radio perform at more than a 1:4 power ratio or a little under it. This is done by setting the carrier to 2 watts and then tuning modulation up slowly while keying radio until it reaches about 8 watts on the meter. I use a 1khz tone from an app off my phone which is something you will want to do as well. I am no radio tech and really a radio should have this work done by a tech or someone with the proper equipment. I have some of it, but there are many important things that I don't have LOL!!

You truly need a 50 ohm dummy load, an App that can make a 1khz sound and then you can inject that into the mic instead of your voice, a watt meter that can also check modulation percentage preferably, if you can adjust for a 1:4 power ratio without one or near that, you are getting 100% modulation or more which can be bad. 90-95% is plenty. Do this by again slowly adjusting AMC. Set dead key to 2 watts and see what amp does. Or 1.5 watts. And make sure all your coax jumpers are good! This is one area that when you add power things can get funny. You will know straight away if you have installed connectors properly or not. A sliver of shield wire might pass with only 4 watts, but add the amps power and things go to shit. Also having an antenna analyzer like this helps tremendously.
Let me ask this. Is your antenna mast grounded to a ground rod. Have you also grounded all your radio equipment to a ground rod. Like JAF0 stated earlier you can cut into the sheathing of your coax and use some 1/2" flat braid or even some flat braid from a piece of coax if it's good shielding and take it to a ground rod. Also make sure all your grounding rods are tied together. Look into how commercial towers or radio towers are grounded and how they go about doing it. This may help with your squeal issue. And you truly need the right equipment to properly tune a radio. A meter that can read power correctly, which you really want a true reading PEP meter, and a good dummy load of 50 ohms. Make sure that your power supply is up to the up to the task like I mentioned above and hope some of this helps. Like I said and will say again, I am not an amp tech and best thing that I know to do is send both radio and amp if possible to a good tech and he can match the radio to the amp and align radio and such. I know it's not what you want to hear, but it's the best way if you don't have some decent money to spend. You just need certain things to tune and align radios the correct way and that is the truth man. Like I said I don't have most of the things to do a proper tune and such! That is why I stay very simple and most of my radios have variable RF power or were bought setup. The only radio I've really messed with a lot is my 980 and a cobra 25. But I did learn how to at least set my dead key and modulation!! That is all I need. Would like to have a full alignment done and a proper tune but I have HF radios as well and use them now mostly!! An Icom 746 and a kenwood ts140s. And like I said, i don't need to get inside them or need an amp! Good antenna setup and 100 watts on SSB is plenty for me! Heck I get on AM every so often when the conditions are good here. I started out as an AM guy. Anyhow, just my own experience and how some things should be done.
Again I know most of it is stuff you don't want to hear LOL, but I promise you need some gear to accomplish things the correct way. Tuning the radio with your antenna may be the issue. Things change as you move up/down in frequency on an antenna due to reactance and resistance. Just because your VSWR is flat from channel 1 to channel 40, other variables change. And when you are tuning a radio you need set things and no reactance which a dummy load provides across that large frequency span like 0-3GHZ or more on some dummy loads. Your VSWR, impedance, and reactance pretty stay the same across that entire frequency span. Your antenna can't do that. Anyways. Keep researching about properly tuning and alighting radios and see what equipment they recommend at the very least. And make sure all your equipment is grounded. Look into grounding a radio base station. It's an important thing to do as well. Again, just want to help man. May seem harsh but I am not trying to be that way I promise man!! Just want you to know what is right/wrong and is needed as well. Have a good one and hope you get it all resolved!! Be safe as well!!

mattsowders1989
10-29-2016, 09:49 PM
I'm sorry 222, I thought I had posted a response to your last post. Yes, I got it all worked out. All is good with the antenna. I have a Hy-Gain Super Penetrator 500 coming in the mail in the next few days. That'll be fun. Thanks for all of the help and taking YOUR time to help me. Skip seems to be picking back up here in Kentucky. I hope we can make contact some time in the future. Thanks again for everything you have helped me with and shared. 677 is getting on down and back quiet.


Sent from my iPhone using Tapatalk

222DBFL
10-29-2016, 10:12 PM
No worries man. Others helped as well. But I am glad to see you have gotten everything working well and now have a better antenna coming. Take your time putting it together and follow the directions to a T!! You'll be happy with that antenna. I am in the process of placing up a dipole facing your way at about 50ft give or take. That should get me to you no problem if the conditions are there! I will also be placing my vertical antenna back up as well here soon. Think I am just going to re mount it where it was before and use the existing 2 2" pipes as braces for the 3rd pipe. Going to go a little higher this time, getting above 30ft to the base. At any rate, if conditions per
It I will catch you on the air 677! Be safe putting up the new antenna and have fun man!!

mattsowders1989
10-29-2016, 10:16 PM
Sounds good buddy. I've been thinking about setting up a dipole to just play around with. Anywho....... I'll be out there when the conditions come about. I'll be looking for you. Honestly, it'll be an exciting day for me. I'm all about that DX! I have my local buddies. But I love skip.


Sent from my iPhone using Tapatalk

222DBFL
10-30-2016, 05:46 AM
I used to have 2 dipoles up at about 35ft up gone or take. One headed N/S and the other E/W. They were far enough away from my vertical antenna as to not cause any issues. I also used a Low Pass Filter with them and a Diawa switch box. At any rate they worked very well! If I had a rough time hearing someone I would flip over to one of the dipoles and it would kill a lot of unwanted noise from places I wasn't trying to talk to!! I took them down as the DX starting dying off as my Sirio vector 4000 did a well enough job. Not to say I don't like the dipoles as at least one is going back up real soon. Then I need to get my vertical back up. But with the dipole up at least I can talk locally to about 4-5 miles and DX is not an issue as long as the way I am facing has the conditions!! They are easy to put up if you have a couple large trees in your yard not too far apart. Or do like some and use only 1 branch and make an Inverted V. I like being horizontal as I have the trees to do it and it cuts down on the noise a lot! And they are truly easy to make or buy one. Just make sure if you buy a pre made one that it has a 1:1 current/matching balun. This will help with CMC issues and also match your unbalanced 50ohm coax to make it balanced to 50ohms going to your radio. There are many different names used for them so just be aware what to look for.
Dr. Dipole makes a pretty good one. But you can find others that are just as well made. This seller that I posted photos of seems to make a good one. http://uploads.tapatalk-cdn.com/20161030/473d92984b46ae1f564c28c9b3d4cd6b.pnghttp://uploads.tapatalk-cdn.com/20161030/f2634bd0197916321bbbef7dc86ebcbf.pnghttp://uploads.tapatalk-cdn.com/20161030/019e7a4e48ddcdbfaa4ee62ca68ef0f0.pnghttp://uploads.tapatalk-cdn.com/20161030/c9a4633d4359914fad6d9e0bece667b6.png

If you build one you can use the proper mix of ferrite chokes and they make a kit that goes around most coax sizes and come with heat shrink. These work too but I don't think as well as the 1:1 balun.

If you do decide to make one you can use some RG6 or Cable TV coax. It's 75ohm coax. You can make a matching stub with a piece of it and get your impedance down to 50 ohms. It is just about cutting the antenna to be resonate on one frequency. The one I posted pics of is precut to 27.200MHz. That is pretty much Center of the CB band and you should have a good bandwidth to cover both above and below the regular 40 channels or freqs for CB. Just some babbling LOL. Seriously. After I built my first one and hung it no more than about 10-12ft off the ground and having nothing more then a radio shack VSWR/Power meter to use for tuning, I managed my first time contact to Australia on a uniden PC122XL. That is from the east coast of FL!! Granted conditions had a lot and I mean a lot to do with it. But it goes to show you can make contacts worldwide on a homebrew 1/2 wave dipole!
Have fun putting that penetrator 500 together! Take your time and make sure you follow the instructions to a T and if you feel uncomfortable about what the actual length of things are supposed to be, come here and ask. A few guys use or have used that antenna and say it's a bit hard to tune, but if you tune them right they work very well!!! Be safe as always and make sure to use some corrosion aid on all your screws and bolts and such. Self amalgamating tape is really good stuff to use on the joints as it keeps water out! You can get the stuff on Amazon or even at Home Depot. 3m makes it as well as a bunch of other companies. Also goes by self fusing tape.
Anyways. Hope all goes well and will hopefully catch you on the air man. Be safe and take your time!!

73 and God Bless.
222 Daytona Beach, FL.

Jay Mojave
11-01-2016, 09:00 AM
Hello All: Yes these 1/2 wavelength dipole antennas work very well, better than the non ground plane fiber glass antennas from my experience. The only thing is that they require to be hung up from a tree or what even to be vertical as all the rest of the CB world. Or can used horizontal say for skip and such.


The home made dipole antenna can be made real cheap with two lengths of 103 inch wires and a 1 to 1 Current Balun, that is shown all over the net. Basically two wires wrapped around a Toroid Core type transformer, 8 to 10 turns, coax connected to the two input wires, the two 103 inch wires connected to the two output wires. These type antennas can take a couple of KW with no problem. I know guys who have these type of antennas strung up going different directions and polarities for switching them around to the strongest signal for distance DX stations.

The toroid core I use is a Amidon FT240-K toroid core at about 19 dollars each. See:


http://www.amidoncorp.com/ft-240-k/

I will use two of these cores epoxied together for the lower ham bands for a 1 to 1 current Balun.


Jay in the Great Mojave Desert

mattsowders1989
11-01-2016, 09:09 AM
I've got a Hy Gain Super Penetrator 500 coming in the mail tomorrow. It's a vertical 5/8 wavelength antenna


Sent from my iPhone using Tapatalk

222DBFL
11-01-2016, 06:15 PM
Yep Jay, I've found the dipoles to be a great antenna for DX'ing myself. And for SWL as well as for use on other bands with a tuner. They are cheap to make and do work well even when placed not real high off the ground. 18ft and you can do wonders. At 35ft which mine were last up at, man they worked great when the DX was rolling to keep up with guys. I too would switch between my 2 dipoles and my vertical and was able to switch polarity to horizontal when the vertical was in/out and vise versa. Helped to make many contacts for next to nothing cost wise compared to other antennas.
Matt, you just take your time putting up that spt500 and tune it correctly and it will work well for you. There are a couple of good mods that can be performed to the antenna as well that help. Do a search for mods for that antenna and you'll see what I am speaking of. And be safe placing it up. Try to get as many people to help you as possible to avoid bending the antenna or possibly hurting yourself trying to get it up in the air. JMHO's. Have fun with it and again, be safe!!

Jay Mojave
11-02-2016, 07:54 AM
Hello M1989: Good deal on the Penetrator 500 hope it all works out for you. Hy-Gain rated this antenna at 1500 watts due to the CLR Antennas that they made before, were being burned up, a small matching coil in the base insulator made on a circuit board. The Penetrator 500 was a big upgrade.

Be advised I hear reports that the new SPF 500 antenna is shorter and guys are having problems getting them on the CB Band. Here is the assembly instructions for the new SPT-500

http://www.hy-gain.com/support.php?productid=SPT-500

The older Penetrator 500 assembly instructions are at:

http://www.cbtricks.com/ant_manuals/hygain/model_500/graphics/hy-gain_500_penetrator_1975.pdf

And a few of the later versions of the Penetrator 500 are at:

http://www.cbtricks.com/ant_manuals/hygain/model_500/index.htm

Using a Antenna Analyzer will allow you to sweep the frequencies seeing were the antenna is working at or better said having the lowest VSWR. The Antenna can be adjusted for were you want it to work. There is a excellent article on this in this section of the Forum, called "Hy-Gain SPT 500 Super Penetrator"

Good luck, please let us know how you made out there...

Jay in the great Mojave Desert

mattsowders1989
11-04-2016, 09:00 PM
Well I got the SPT-500 up and running. I took my time tuning it. SWR is flat for the most part. Past Ch 30, it hits a 1.1:1 witch I'm happy with. It was a bitch to get up but with a little help from the old man, I got it up and going. I will post pictures tomorrow with the daylight. It's hearing and talking far though!!


Sent from my iPhone using Tapatalk

mattsowders1989
11-08-2016, 10:54 AM
http://uploads.tapatalk-cdn.com/20161108/18994dac65ee0f9973b80cd634262619.jpg


Sent from my iPhone using Tapatalk

mattsowders1989
11-08-2016, 10:55 AM
I hit skip this weekend barefoot on 4 watts. It was only one small contact but it happened. Everyone says I am getting out there strong and loud


Sent from my iPhone using Tapatalk

222DBFL
11-09-2016, 06:15 AM
Good job. With the way conditions are that isn't bad at all. If the band is quiet and you get a good signal coming in just goes to show you don't need a lot of power to get back to them!! Now it might've been different if there were a bunch of people on the band or frequency you were on. If that is the case. Which I think it may have been. Right place and right time!! Job well done. Enjoy and keep at it.
If you haven't already done so, now would be a good time to make yourself a log book and start logging all your contacts. Get all the info you can. Date, time, signal report, numbers, name, frequency or channel, and so forth. It makes it easier when you again speak with someone you think you have spoken with in the past. Just some food for thought. Again, have fun and enjoy that new antenna setup. Looks good man!!

Jay Mojave
11-09-2016, 10:42 AM
YO M1989: Can you tell us what lengths the antenna was assembled at, would help others out.

Jay in the Mojave

mattsowders1989
11-09-2016, 10:46 AM
Total vertical length is at 26' 6.2"
That's from the bottom of the coax connector to the top of the screw for the hat. The radials are 104" each. Flat SWR until Ch 30. After ch 30, SWR is 1.1:1

Great performance.


Sent from my iPhone using Tapatalk

Jay Mojave
11-10-2016, 10:15 AM
Hello M1989: Great looking install there glad its ah hummin and buzzin for you. Kind of nice to have such a low SWR.

26 Feet 6.2 inches sounds a little too long, did I get that right? Is it possible to get the bottom 1 1/4 inch tubing length? Its not given in the assembly instructions. But the older Penetrator Bottom Tubing length was 71 inches.

Thanks for any help here.

Jay in the Great Mojave Desert

mattsowders1989
11-10-2016, 10:17 AM
22' I'm sorry. Not 26'


Sent from my iPhone using Tapatalk

Jay Mojave
11-12-2016, 08:40 AM
Hello M1989: A big thank you, greatly appreciated. I changed the batteries in my caculator as I was trying to make the lengths fit. Even cleaned ny glass's. Good to hear its working for you. Thanks again.


Jay in the Mojave

mattsowders1989
11-13-2016, 11:40 AM
its a hell of an antenna. using a cobra 29lx going into a typhoon 150, that is driving a heathkit sb-200. im putting out about 800 watts and im being told that i sound really good out there. thanks guys for all of your help. i thank each and every one of you! and thank you doughboy for the typhoon 150!

source
01-06-2017, 12:52 AM
1\4 wave has no gain use sigma or vector 4000 updated to the sigma .very effective.

.

222DBFL
01-06-2017, 05:57 AM
Yep. Run a vector 4000 myself. Good antennas if and I say if due to the length, you don't live in a high wind area. Another great antenna that is getting a lot of attention is the Hy-Gain SPT500. Good antenna as well. And if you want something you can run more power through, look at the US made Shockwave antennas. They aren't cheap. But they aren't built cheap either. JMHO's.

BOOTY MONSTER
01-14-2017, 08:00 AM
vector 4000 is a great antenna ... if you have the space and mild weather for it ... and the budget . but folks have talked around the world on 1/4WGP's , they can be very effective !!!

JAF0
01-25-2017, 02:52 AM
Yeah, that SPT-500 (NEW-School Penetrator) is a thing of beauty!

Does the entire antenna from bottom of coax connector to tip of top hat rods bolt measure right at
22' 6"?

I run an original 1975 Penetrator-500 by (Pre-MFJ) Hy-gain and had to shorten it about 2" from 22' 9.5" to 22' 7.5" total to get it flat from 10 ch below ch1 to 10 ch above ch40, centered on ch19, middle of the band because it centered right at 27.000 out of the box at 22' 9.5".

Appears the new version is real close, differing by only an inch or two. That's good because my original kicks arse!!