Re: Gordon Gibby Digital Interface

Sascha Bohnet | DL5SMB

Still fighting to get the interface working.

I did make direct solder connections to the usb sound card - but the problem was something else. I did not pick the hot end of the poti but the wiper. So the RX path is pobably okay now.
But if i try to go to TX mode, the radio switches to transmission (vox) but I do not get any output out.

Comparing Davids schematics with Gordons original circuit, I noticed a change of resistors, probably  a confusion:

R3 which connects the sound cards left left output channel to the 500 Ohm Poti before the tranformer is a 47k resistor in Davids kit,
in Gordons documentation this resistor is 4,7k oder 10k (depending on the signal level) and is referenced to as R12.

In the vox circuit of Gordons documention the signal of the right audio channel is led through a 47k resistor to the base of the transistor Q1 -
in Davis kit this is a 4,7k resistor.

I will check tomorrow if changing both resistors helps in my case. And then I will give some feedback to Rob about the C60 tapping :-)

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