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rci 2950/2970 internal talk back

purenrg

Member
Jan 27, 2009
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Is there anyone with this mod in there radio? This mod calls for the removal of D78, or removing of one leg of D78 going to a switch on this to ground. so talk back can be turned off and back on as needed. Just wondering if this is the best way to go? Or to use echo board w/talk back in it.

And what board would be the best to use? Any tech input would be helpful, I just don't won't to wast money w/junk, or butcher up a good radio.
 

well this doesnt answere your q but its what id do.id simplyn
buy a rflimited echeo mic.they add talkback to most radios ive hooked
them up too.and the talkback is variable.plus ya dont have to butcher
a good radio
 
Do as HotRod suggested... my buddy tried the talkback mod in that thing and it didn't work well at all, just a bunch of howling coming from that thing. I know there's a mod that you can do on the newer DX rigs, but you have to lift a SMD resistor up and add a few transistors in series to keep the TB level down.
 
RCI-2950-70 pre DX Talkback mod.jpg

Pre-DX RCI-2950-70. No need to cut or lift D78, as the unmute circuit Q41 does this in CW TX mode. Only need to ground the center pin of Q41 and add a resistor/cap from the output pin (Pin1) of the mic preamp chip (4558 dual op-amp), to Pin4 (input) of the TA7222 speaker amplifier. Could use a 1 meg, 470k, 330k, 220k or 100k, any value between. Lower values are louder (feedback squeal possible??).

By the way, this works in all modes, AM/FM and SSB. It clears up the muffled "Donald Duck" sound otherwise heard on the SSB modes.
 
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