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3600 board mod

2FB327

Active Member
Oct 31, 2012
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I pulled off the cover and this is what I found, does anybody have an idea what this person was trying to do?
He took the time to put hear shrink on it and never heated it.
3600 1.jpg


3600 2.jpg
 
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That's the "Talk-Back" volume reduction mod.
Straight from "Galaxy Radio", this one works good if the radio has been "peaked n tuned" or NPC modified, if the radio squeals adding the right amount of resistance here, or disabling talk-back will fix the "squeals with the mic gain up" problem.

ssb_fm_talkback.jpg


You could measure the two resistors in series and replace them w/ a single one of a similar value, just to clean up the look. Honestly the tape or heat-shrink is a good idea, but really most times this will sit flush enough with the PCB so you can put the lids on and not have any short circuit issues.

You could simply remove it all together, but if you suddenly have a feed-back issue with the "Talk-Back" circuit you will know why!
 
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Yeah the blue link in my post will take you to Galaxy Radio's [maybe] "Official" website.
They explain what value resistance to test out with in the beginning, and how lowering or raising the value affects volume.

I've never tried a D104 on a Galaxy, that'd be a pretty cool combo if it had worked at the time.
The photo in my previous post came from the Galaxy website, it is not my work.
It's all good I appreciate it when you guys remind me of something or help explain a thing that I didn't know about before! Sharing Links is half-the battle LOL.
(y)
Not my words:
Talkback Mod

Talkback can become distorted if these radios have been "peaked," and there is no cure because the talkback just amplifies what goes to the RF section. Try adding a 470k ohm resistor from junction of C154/R207 to the junction of C187/R235 on the solder side of the board. This will also give you clean talkback on SSB and FM. Try different values of resistance to get the amount of volume you want. The less the resistance the louder the talkback will be.
:cool:

Disabling Talkback

DX 33HML Disconnect wire located in TR30

DX 44V Disconnect wire located in J15

  • DX 66V
    Disconnect wire located in J15

    DX 73V
    Disconnect wire located in J15

    DX 77HML
    Disconnect wire from resistor R244

    DX 88HL
    Disconnect wire located in R189

    DX 99V
    (original type echo board) Disconnect wire located in TR35

    DX 99V
    (smt type echo board) Disconnect wire located in J15 next to R244

    DX 11B
    Disconnect wire from diode located in R244

    DX 22B
    Disconnect wire from diode located in R327
73
 
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I have a local guy that does this mod to every radio that goes out the door from his shop. So I'm very familiar with this mod.


~Cheers~
I have done it to all of my ept3600 rci radios.
On one I have talkback disable on a switch.
You can also get creative and make talkback work independent of the echo on a double throw switch. (sometimes it's nice to have TalkBack and no Echo)
 
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