[aprssig] FTM-350 cables

Julian, G4ILO julian.g4ilo at gmail.com
Thu Mar 10 15:45:58 EST 2011

Yep, I can't imagine why anyone would pay all that for a device that
still expects you to buy a sound card or give up the built-in one.

I made something similar to the one you did using one of the
ubiquitous USB sound devices costing a few bucks:
http://www.g4ilo.com/usblink.html . It's based on a circuit by Skip,

A word of warning. The clocks in these cheap USB sound devices are not
very accurate and that can cause problems with 1200baud packet signals
being decoded because the baud rate is wrong. Using TrueTTY for the
packet modem you can set the clock speed to whatever it actually is.
The one in the interface I made runs at 11050Hz while another one I
was experimenting with turned out to need 11100Hz to generate a
1200baud signal. The AGWPE doesn't seem to have a clock speed
adjustment, at least not on the transmit side, so it's best not to use
that program with sound cards that are not of proven accuracy or
you'll end up wasting a lot of time like I did.

Julian, G4ILO
G4ILO's Shack: www.g4ilo.com

On 10 March 2011 17:08, Stephen H. Smith <wa8lmf2 at aol.com> wrote:
> Especially ironic, considering that the Signalink costs $20 LESS than the
> West Mountain device!
> I've been making a homebrew equivalent of the Signalink using the tone-keyed
> interface shown here on my website:
> <http://wa8lmf.net/ham/tonekeyer.htm>
> mated to a Griffin Electronics "iMic" external USB sound system described
> here on my website:
> <http://wa8lmf.net/ham/imic.htm>

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