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Mr.5150cbrn
06-10-2012, 08:09 PM
ok coax question #1. -
if the length doesnt matter when running a given length of coax
then why does it make a difference with resonating the length to a given frequency verses the vf?
also when i use a analyzer i get a different reading than with a swr meter

BOOTY MONSTER
06-11-2012, 07:58 AM
your answer is in this thread already on the forum .

http://www.cbjunkies.com/threads/157-Some-great-information-about-coax-lengths-and-swr?highlight=velocity

Mr.5150cbrn
06-11-2012, 08:13 AM
also noting that the swr bridge was adding standing wave into the mix

so with that i tried using a different meter inplace of the other one - different measurements
neither of which , i may add came to near what the MFJ was saying

coolbreeze
06-11-2012, 11:16 AM
meters can not measure the impedance and capacitance of the antenna system. They only read fwd and reflected power.
the mfj can see much more.
I have personally seen changes in performance by altering coax length. both in the feed line and jumpers.
Once again real life findings.

What the average t bag doesnt understand ( resident who ) is each foot of coax has capacitance to it. Jumper length matters due to this!!! it can does and will affect the input or output tuning of the amplifier.

if you dont use 1/2 wavelength intervals with VF factored in on your antenna, you may as well try sucking a milkshake through 12 in of big straw and then 2 in of a coctail straw. its not optimal. But you dont have to believe me. The ones who dont can go on being the biggest duck they can be.

BOOTY MONSTER
06-11-2012, 11:35 AM
meters can not measure the impedance and capacitance of the antenna system. They only read fwd and reflected power.
the mfj can see much more.
I have personally seen changes in performance by altering coax length. both in the feed line and jumpers.
Once again real life findings.

What the average t bag doesnt understand ( resident who ) is each foot of coax has capacitance to it. Jumper length matters due to this!!! it can does and will affect the input or output tuning of the amplifier.

if you dont use 1/2 wavelength intervals with VF factored in on your antenna, you may as well try sucking a milkshake through 12 in of big straw and then 2 in of a coctail straw. its not optimal. But you dont have to believe me. The ones who dont can go on being the biggest duck they can be.

what about when you change the channel and it's no longer a electrical half wavelength ?

so ...... if is not on the one channel that it's perfectly tuned for it will perform as well as "sucking a milkshake through 12 in of big straw and then 2 in of a coctail straw" ????
since it's no longer a electrical half wavelength because the channel was changed .... ???

how in the world do hams manage to talk around the world using such wide bandwidth transmitters ?

don't get me wrong , i am a fan of using electrical half wavelengths of coax centered on your favorite band or most used frequency/channel . i'll disagree on the amount of signal loss you suggest by not having the correct length of coax . and so do millions of other people .

Mr.5150cbrn
06-11-2012, 05:31 PM
ok then the meters cant read capacitance or inductance
but in my findings ( real world ) meters can also add to the swr nightmare by increasing standing waves- some worse than others
as shown by the readings from the mfj anylizer of the antenna system

Gordon Gekko
06-11-2012, 06:41 PM
meters can not measure the impedance and capacitance of the antenna system. They only read fwd and reflected power.
the mfj can see much more.
I have personally seen changes in performance by altering coax length. both in the feed line and jumpers.
Once again real life findings.

What the average t bag doesnt understand ( resident who ) is each foot of coax has capacitance to it. Jumper length matters due to this!!! it can does and will affect the input or output tuning of the amplifier.

if you dont use 1/2 wavelength intervals with VF factored in on your antenna, you may as well try sucking a milkshake through 12 in of big straw and then 2 in of a coctail straw. its not optimal. But you dont have to believe me. The ones who dont can go on being the biggest duck they can be.

You're a Ween

Mr.5150cbrn
06-11-2012, 08:30 PM
You're a Weenthats right
and your still in the swamp
quack quack

coolbreeze
06-11-2012, 09:48 PM
5150 you are correct. A bird meter is the only one I have found that does not affect the antenna line. My freaking dosy adds alot of reflect

booty when changing channels coax length would be inches different. do you have adjustable coax?
if your coax is feet off what would be perfect, now thats going to be a change. changing channels is not. bands could be.

Mr.5150cbrn
06-11-2012, 10:24 PM
5150 you are correct. A bird meter is the only one I have found that does not affect the antenna line. My freaking dosy adds alot of reflect

booty when changing channels coax length would be inches different. do you have adjustable coax?
if your coax is feet off what would be perfect, now thats going to be a change. changing channels is not. bands could be.


adjustable coax ? WTF this smells of some serious 'AMPOWER

coolbreeze
06-11-2012, 10:36 PM
lol nice
cordless coax is what am power uses

Gordon Gekko
06-12-2012, 04:05 AM
5150 you are correct. A bird meter is the only one I have found that does not affect the antenna line. My freaking dosy adds alot of reflect .

so what you're saying is that the only way to get an accurate swr measurement is by using the mfj or using the Bird (5150's favorite) with the slug backwards? All other meters will lie?

coolbreeze
06-12-2012, 07:27 AM
whatever the dosy says for swr, the amp is seeing a higher swr due to interferance with the meter. take one apart and it will be as clear as day,

Gordon Gekko
06-12-2012, 08:16 AM
whatever the dosy says for swr, the amp is seeing a higher swr due to interferance with the meter. take one apart and it will be as clear as day,

so what you're saying is that the only way to get an accurate swr measurement is by using the mfj or using the Bird (5150's favorite) with the slug backwards? All other meters will lie?

Mr.5150cbrn
06-12-2012, 08:55 AM
so what you're saying is that the only way to get an accurate swr measurement is by using the mfj or using the Bird (5150's favorite) with the slug backwards? All other meters will lie?

pretty much so .
but if you set up in the beginning using the preferred equipment , you know your values, limitations ,
and the meters limitations
the meter is only a monitoring device