Discriminator tap on GTX Portable

Victor Xray · Post by **Victor Xray** » Tue Nov 07, 2006 2:45 pm

Looking for the discriminator pad/pin on a GTX portable. Thanks!

kcbooboo · Post by **kcbooboo** » Tue Nov 07, 2006 3:34 pm

First thing I must ask: why?

It's called detected audio on the schematic. It's not at all easy to get to. It starts up near the volume control but the signal immediately goes under the IF IC. If you can probe around the connector going to the display board, it's on pin 4, but I can't tell how it gets there from the IF IC. I need a magnifying glass just to see stuff on the board X-ray view, and that's bigger than the radio itself. Pin 1 is nearest to the center of the board, close to what looks like a hybrid or metal can.

Anything else would require me to mail you several hi-res (i.e. BIG) scans of the schematic and board layout.

Bob M.

Victor Xray · Post by **Victor Xray** » Tue Nov 07, 2006 3:45 pm

Why? For fun

Experimenting

Thanks Bob, that helps a lot.

kcbooboo · Post by **kcbooboo** » Tue Nov 07, 2006 3:52 pm

I can tell you that on the display board, the audio IC gets it into its squelch input as well as its PL input, so it must be pretty flat at that point. I don't know if it would be any easier to tap it there, but as these radios weren't meant to be serviced by the mere mortal among us, good luck!

There's also an RSSI signal floating around, mainly for HearClear. In fact, there's a LOT of stuff running around the radio. The service manual I have is p/n 6802948C90 for the GTX/GTX LTR/LTS 2000 Portable Radios.

Bob M.