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47GHz Experiments

VK3DAG used a 26GHz Thales unit on 23Ghz as a 47GHz LO:
http://vk2dag.com/cm/47-ghz-up
http://vk2dag.com/wp-content/uploads/2012/10/harmonic-mixer.jpg

I have some 23GHz link parts in my junkbox so this got me thinking. 
The LO's are thermally stabilized 23.xxxGHz Gunn-oscillators that ware directly modulated for transmit. 
But the Gunn's ware also phaselocked by harmonically mixing them down to a lower frequency and then using a garden variety PLL. 

They can be directly modulated so wide FM and FM ATV should be possible. 
I don't have any filters for the 47GHz band nor interest in making them for a kludge like this so the IF needs to be below 2x IF = 250MHz as the 47GHz band is only 250MHz wide. 
So without filters 70MHz is the highest hamband that's usable. 
That is, if I ware to use it as a more traditional transverter. 
But as we are directly modulating FM-ATV or wide FM, the IF can be what ever we want (as long as it's under 250MHz, so that the otherend of the QSO can also work us.) Basically this is just a little weird Gunnplexer rig with the TX & LO at f/2.
Conveniently the FM demodulators in many satellite TV receivers operated at Low-VHF so those should be usable as IF demodulators for TV. 
Ditto for modified broadcast receivers for wide FM.

Using stuff like modified 27MHz CB's for IF might be tempting, but who knows how horrible the phase noise is going to be. And even with a phase locked LO, it's gona drift. Better use a rig with a clarifier. 

As a mostly useless bonus, the original harmonic downconverter for phase locking also has a separate RF input with 23GHz preamp, bandpass and fundamental mixer (on 23GHz) for downconverting 23GHz to the 1-1.4GHz IF. That would allow using an analog satellite TV tuner as an IF for receiving 24GHz FM-ATV. Yay. Or AR8200 for wide FM. 
That would allow operating fancy modes like 47GHz/24GHz split FM-ATV or wide FM voice. Because why not?

For a 47GHz monitoring downconverter I plan on using a simple antiparallel diode harmonic mixer on a piece of semirigid and a 22.xxxGHz DMC brick oscillator. With AR8200 (or RTL-SDR) as the IF rig it should be very usable for monitoring the output of various transverter kludges. 
With an additional cheapo Ku-band LNB connected to it for downconversion from 9-10GHz IF to something usable, it might also work for 76GHz testing. 

Yet something more to do with all that "useless" junk available at hamfests and my junkbox. 

-OH2FTG 2017
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