AO-40 K-band Receiver
Created 3 April 2002
Here's my DB6NT based 24GHz AO-40 downlink setup. Hopefully near to getting some success, but on the one occasion I tried, no luck. Wiggling the dish about aimlessly, manually scanning the band, guessing the frequency and only a few minutes to try each pass means it's a tall order.
Hmm... failed first attempt
That dish has a 3dB beamwidth of about 2 degrees. Careful and accurate pointing are the order of the day.
I used the sun as my signal source (very easy to point to with this dish on a sunny day - simply turn the dish until the shadow is non-existent). The horn feed lights up. And you hear a very marked increase in the noise level on an SSB receiver.
DB6NT's Suggested AO-40 K Band Receiver Downlink
Receiver in the flesh
All the parts except for the waveguide filter are off the shelf.
o DB6NT MKU12 LO 11952MHz Local Oscillator
o DB6NT MKU243 WS Waveguide preamp, 2dB NF
o DB6NT MKU24 RXO Mixer
o PROCOM PRO-24-001 Dish + Feedhorn +Feed assembly
I discovered that obtaining a waveguide filter is rather difficult to say the least, so I decided to have a go at building one myself.
Original plans for the waveguide filter