View Full Version : Direct Injecting a Galaxy or Connex type

03-22-2013, 03:02 AM
Hey guys here is the direct injection mod for galaxy and connex type radios, such as 33,44,55,66,73,77,88,99,3300hp,genral lee and some others that use this board.
You will need the following: 1 - cap between 3uf - 10uf no more than 10uf. 1 - 1/4 mono jack chassis mount. 1 - on/on switch. wire and soldering stuff.

1. Drill and mount the switch and mono jack. 2. Locate and remove C191. 3. Solder + leg of cap in hole closest to middle of radio. 4. Solder A wire from - side of cap to center pin of on/on switch. 5. Solder a wire from one side of the switch to the other hole of C191. 6. Solder a wire from other side of switch to the + side of mono jack. 7. Solder - side of mono jack to board ground (you can solder to a can).

Ok if you are using a mylar style cap it doesn't matter which side of the cap you put to the board but just make sure it goes to the hole of C191 Closest to Middle of Radio. I used a Tantalum cap which has a +/- leg. Ok you will also need away of keying radio either a foot or hand switch or even a stock mic with audio wire unhooked. but these radios a 4 pin mic plugs so they are very easy to make a foot or hand switch. If you need any help with making a foot or hand switch please ask and I will help as much as I can. I will post a new post later with all my foot and hand designs for 4 and 5 pin radios. I hope this will help someone have fun and enjoy!!!

08-11-2013, 05:39 AM
can you do this with a stonewall jackson and if so can you pleas help me im tird of spending money on things and not geting what i want to hee thank you (jake):wave:

Silverado 996
02-02-2014, 10:44 AM
Thanks for the info.

02-15-2014, 11:25 PM
Not to sound stupid but is direct inject what you are doing when you use a mixer and studio mic? And will this work on a pc66xl and a galaxy959 also?

Silverado 996
03-03-2014, 10:09 PM
Not to sound stupid but is direct inject what you are doing when you use a mixer and studio mic? And will this work on a pc66xl and a galaxy959 also?

Look up direct injected galaxy 959 on YouTube. There a few cats on there laying it down.

03-06-2014, 02:41 AM
Direct Inject is when you connect your audio gear output to the internal modulator of your radio,bypassing the internal microphone pre-amplifier and limiter

People think that a mixer is needed to run audio gear but the reason that a mixer is used is because of the audio pre-amplifier built-in

You can use a: microphone + pre-amplifier (solid state or tube) + equalizer + compressor/limiter connected to the microphone input of your radio or straight to the internal modulator

When using the mic/input the internal radio microphone pre-amplifier needs to be modified to pass more audio bandwidth

Hope this helps

08-17-2015, 10:45 PM
I wonder how this would work on my HR2600. Anybody try it?

04-23-2016, 07:11 AM
Whats the differences in the type of cap, and the values used for this mod? I just used a 10uf electrolytic.

04-23-2016, 07:19 AM
I'm also curious how this would work with this mod below, or am i bypassing it by direct-injecting? Goldfinger's HiFi mod for ept3600 series board


C36: Change to a 2.2uF, 50 Volt (or better) mylar/polyester film
C38: Remove for more highs
C39. C154, C155: change to 2.2uF 50 volt (or better) Non-polarized electrolytic or mylar/polyester film
C157: Change to a 2.2uF, 16 Volt (or better) tantalum (observe polarity)


C129: Change to a 10uF, 16 Volt (or better) tantalum (observe polarity)
C187, C191: Change to 2.2uF, 50 volt (or better) mylar/polyester film

01-16-2017, 12:04 PM
radio's using EPT069611A board ( 2547, 939, 949, 959,) process same as above except location is c235. If using polarity type capacitor neg. lead goes to switch, positive lead goes to vacated hole at c235 closest to middle of board ( component side up )2253225422552256

smoke blower
02-21-2017, 07:36 PM
Can someone tell me all of the cap mods for a cobra 29 LX le

07-25-2017, 08:00 PM
Hello !

I have an old crt cx4000, according to http://78roger.free.fr/ref_platine.htm , it uses the same board ( ept360014b ) than galaxy and 3300hp.
I'd have fun to try this mod on it, but I wonder if it will also work on SSB ?

EDIT : So it works very nicely in AM. line level from my pc is just fine, the audio is really beautiful.

I didn't find a way to route it to SSB yet. Trying to figure that out :)

Thank you for the great info anyways !

12-27-2018, 02:06 PM
Any info available for injecting the magnum s9 w 2 1969's ? It has evaded me as of yet...

12-15-2019, 08:26 PM
Very easy install however I get a loud buzzing sound in my on air audio. Could that be a grounding issue? If I talk into mic, I can hear a change in the buzzing but not legible.