[Boatanchors] Possible VFO???.
wcarns at austin.rr.com
Mon Apr 10 07:22:06 EDT 2017
Lee. I would be very leery of using this as a VFO. You are going to have to
do a ton on technical work work regarding birdie and spur analysis and you
will need some good test equipment including a spectrum analyzer. It is not
just a matter of thinking about harmonics. DDS generators can be pretty
dirty of not well engineered and implemented.
Regarding the "mute function" during receive. I doubt that it has provisions
for this and you are going to have to do some real analysis of the guts of
the thing to see if this can be implemented either in a mute or shift
manner. 're the doubling and tripling to get up to 20 and above, yes you
could do this. This kind of approach - regardless of signal source, depends
upon distortion of the waveform in the doubler or tripler - etc. - in order
to generate harmonics. If you look at the oscillator waveform of a crystal
calibrator, you may not like what you see. The waveform is intentionally
distorted in order to generate harmonics all the way across all bands up
through 10 meters.
It all could work, but you have a nice engineering job in front of you.
Some may even say they have "done it" but without the engineering, be
From: Boatanchors [mailto:boatanchors-bounces at puck.nether.net] On Behalf Of
Sent: Sunday, April 09, 2017 8:42 PM
To: boatanchor <boatanchors at puck.nether.net>
Subject: [Boatanchors] Possible VFO???
Could you use this generator as a VFO? Would you need a low pass filter for
it? For 40 meters and above, would you use a 40 meter signal for all bands
40 thru 10 meters? I suspect so as most old boat anchor rigs used 40 meter
crystals for 40 meters and above. Then the next question is how do you mute
it while receiving. I'm wondering if there would be a way to move the
output frequency while receiving. Possibly a fast acting relay could switch
in the generator while transmitting and switch it out while receiving. I'm
not sure how much radiation would come out of the plastic box while
receiving if it was still on the operating frequency. (This is assuming we
are operating on 40 meters and the generator was on 40 meters.) It
certainly has enough output power to
drive a boat anchor. Anyone on here experimenting with this concept?
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