Gunnplexor from ~1975

[Alexei.Polkhanov]

I got this gunnplexor together with some very old RF stuff. It must be some kind of proximity sensor, automatic door opener or part of something else. By date code of components I assume it is made in late 1970s. Unfortunately it has 1 or 2 components missing on board and nothing comes up on Google except opamps. If anyone knows where it from please share!

Link to hi-res images: https://plus.google.com/photos/116960055711068468555/albums/6080668013301327281

 

[wazzokk]

It looks like a rather cheap and nasty Gunn module as used in some alarm systems they were used in a similar way to PIRs and worked on the doppler principle at about 10GHz. We used to modify them to form the basis of amateur radio wideband 3cm microwave transceivers. They have gunn diode oscillator cavity with a mixer diode in front of the gunn, a reflected signal from a moving body is shifted from the base frequency (doppler shift) and when mixed with the base frequency gives a frequency proportional to the speed of the moving body (hence also used as base for radar speed detectors). Hope that helps.
Regards Dave

[Alexei.Polkhanov]

Thanks Dave,
yes I understood that it is a ~10GHz module since it has a horn attached to WR90 waveguide. Yes it is super-cheap construction. I was not able to find any references to a Gunn diode inside the cavity or detector diode. Even considering how old this thing is I was still expecting to be able to find some datasheets for diode. But no luck.
 
Here are photos of both mixer and Gunn diode. Strangely I find that symbol is kind of wrong - it is not a n-p junction it is more like n+-n--n+. It measures 300 Ohm in one direction and 200 Ohm in reverse - which is normal for Gunn diodes although I expected it to be lower. Both branded as "ALPHA".

[mhzghz]

I don't think it's a Gunnplexer, it looks more like a X-band radar detector.  Those are point-contact diodes to convert the radar pulses into DC voltages.