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've tried connecting to different audio outputs that I can find in
the service manual, but they all have the same problem.

Thanks!

Philippe Signoret

On Oct 30, 10:57*am, 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've tried connecting to different audio outputs that I can find in
the service manual, but they all have the same problem.

Thanks!

Philippe Signoret

You may have a ground loop problem. I suggest the use of an isolation
transformer between the transmitter and receiver. Also pay attention
to signal levels, an attenuator be may be required to achive the
proper audio input level to the transmitter.

Jimmie

You may have a ground loop problem. I suggest the use of an isolation
transformer between the transmitter and receiver. Also pay attention
to signal levels, an attenuator be may be required to achive the
proper audio input level to the transmitter.

Jimmie

Thanks Jimmie. I'll check that and let you know. If I can, I'll run
some tests at my university where I can use the oscilloscope. I'll be
sure to get some images in case the transformer doesn't work.

Philippe

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.

--
/home/w9wi/.sig

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.

--
/home/w9wi/.sig

There are small basic controller boards that you might find helpful for
dealing with several issues.

Other issues to consider:

Think about a full time fan trained right on the PA and power supply and
program TOT to 4 min max. in the FT.
Even then you may find your mobile getting way too hot even on the low power
settings. Even to the point of melting solder. The heat may not travel
fast enough from the device into the heat sink and build up when higher
power levels are selected. This winds up heating up the board too much
Also note the transmitter is spec'd at a drifty 10ppm.

Possible RF energy from the transmitter getting into the RX audio and thus
into the TX audio.

Hams actually put more stress on a repeater than commercial users.

http://infotech.awardspace.com/

On Oct 31, 11:52*am, "JB" wrote:
There are small basic controller boards that you might find helpful for
dealing with several issues.

Other issues to consider:

Think about a full time fan trained right on the PA and power supply and
program TOT to 4 min max. in the FT.
Even then you may find your mobile getting way too hot even on the low power
settings. *Even to the point of melting solder. * The heat may not travel
fast enough from the device into the heat sink and build up when higher
power levels are selected. *This winds up heating up the board too much
Also note the transmitter is spec'd at a drifty 10ppm.

Possible RF energy from the transmitter getting into the RX audio and thus
into the TX audio.

Hams actually put more stress on a repeater than commercial users.

http://infotech.awardspace.com/

Thanks. I still haven't had a chance to see if any of these
suggestions fix the problem, but I'll let you know.

The repeater will be used sparingly only during weekends, I don't
think I should have a heat problem. Either way, I do intend on using a
fan.

Thanks!
Philippe

The repeater will be used sparingly only during weekends, I don't
think I should have a heat problem. Either way, I do intend on using a
fan.

We live and we learn.