Dear Chris, LF Group,
----- Original Message ----- From: "Chris Osborn" <
[email protected]>
...>My initial thoughts were that the PC is giving out a 1500 Hz tone + / - 5 Hz.
This is used to generate USB signals from an SSB TX (?)
I was hoping to mix these tones with a stable frequency of 1400 Hz (say) ending up
with 100 Hz + / - 5 Hz - thence to an F-V converter - gain / level adjusted and thence
to the TX VCO input....>
That is probably feasible, if quite tricky - but much easier just to mix the 1500Hz tone up directly to 500kHz to generate the VFO drive for your existing TX PA; that way only a simple fixed oscillator is required (one using a ceramic resonator would be adequately stable and "pullable" over a sufficient range). You then avoid all the business of having to
calibrate the f/V gain, VCO frequency shift and so on. Plus, you can tune the frequency by changing the centre frequency setting in the software, and use it to transmit all sorts of other soundcard mFSK modes, RTTY etc., too.
Cheers, Jim Moritz
73 de M0BMU
