Fun with gunnplexer's

[TheSteve]

Picked up a pair of Macom Gunnplexer transceivers the other day.
Today was the first power on to verify they are working.
Next is to FM modulate the supply to transmit tones/audio.
After that is is receiver time.
Eventually the plan is to have a pair of limited range, very directional 24 GHz walkie talkies - just cause I can!

I will update this thread with progress as I go.

[babysitter]

Used simiilar ones together with people from my makerspace to do a model speed enforcement car. Complete with flashing LED in case you're over the threshold and external display. (Converted a pink VW Bus from Dickie to a black and white one, hehe...)

[TheSteve]

Finally had a chance to build a quick and dirty 5 volt regulator with a LM317. Audio is fed in to its adjust pin via a 0.1 uF capacitor. The output of the regulator is fed directly into the gunnplexer. With 4 mV of audio I am getting roughly 100 kHz of FM deviation @ 24.13 GHz. The audio demodulates quite nicely but there is a lot of frequency drift. When a receiver is built it will need to have a wide front end.

[ftg]

To necro this a bit, did you end up building the IF receiver for these Gunnplexers?
And if so, that style and did you include AFC?
I have some 24GHz Gunnplexers that have been taking space in my junkbox and lately I have wanted to get them into a more usable state.
And see about making my first 24GHz QSO's with the pair.

[nonius_]

I have some 24GHz Gunnplexers that have been taking space in my junkbox and lately I have wanted to get them into a more usable state.

Wow, that's pretty old skool tech And so is wideband-FM on those SHF-frequencies....

About a decade ago I experimented with Gunnplexers. One got built into a 10GHz ATV-transmitter (analog), worked marvelously on the local ATV-repeater.

Another one (I believe a 24GHz version) I experimented with the Doppler-effect: connect a small audio-amplifier and a speaker to the output of the mixer, point it to the room and walk around in the room, waving your hands about. Endless fun (well, at least for a simpleton such as myself).

At the time I was thinking about turning it into a speedgun (all it required was adding an antenna with a bit more gain, and an audio frequencycounter, calibrated in m/s or km/h), but never got around to it. The Gunnplexers are still sitting in a box in the attic, they're easy to use and pretty fun to experiment with.

At the time I also found a design for a simple Doppler weather-radar, using one. Never got around to building that though.

In my ancient ARRL-handbook (1990) they also describe a design for a wideband-FM communication system.

[KE5FX]

In my ancient ARRL-handbook (1990) they also describe a design for a wideband-FM communication system.

That's probably Glenn Elmore's 2-Mbit link, which I bumped up to 10 Mbits when I lived across the parking lot from my office.  Incredibly fun project, and I got a lot of use out of it.