On Thu, 30 Oct 2008 07:57:25 -0700, Philippe Signoret wrote:

Hello all.

I am trying to build a simple repeater system. This is how I have it set
up:

Kenwood TK-7102 receives on on frequency #1 and is connected to Yaesu
FT-1802 which transmits on frequency #2.

The Carrier Operated Relay output of the Kenwood is connected to the PTT
input on the Yaesu. This works perfectly.

The problem is with the audio. I tried connecting the audio output to
the Mic input on the Yaesu. The result is the audio with a horrible,
high-pitched warble in the background. Any ideas?

I would suggest the audio output level is way too high for the mic input
of the Yaesu. Turning down the volume control on the Kenwood will bring
down the level of the desired audio of the station being repeated, but
there's probably some amount of inherent noise in the Kenwood's audio
amplifier that isn't affected by the volume control. Since the Yaesu's
audio input is far more sensitive than the Kenwood's speaker, you're
hearing that noise.

A simple voltage divider would fix this. To toss out some values, maybe
a 100-ohm resistor on the grounded side, in series with a 10,000-ohm
resistor on the "hot" side, and tap the audio to the Yaesu across the 100-
ohm resistor. I don't guarantee you it'll work but resistors are cheap &
it's worth trying.

Do you have any method of ensuring the Yaesu won't get locked in
transmit? (is there a timeout timer function?) Especially if you're
using carrier squelch (not subtone), a spurious signal could leave the
carrier-operated relay open and lock the Yaesu in transmit for a long
time - possibly damaging the power amplifier. Not having a timeout may
also be illegal in some countries.

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