For the summer of 2011, I've started a project within the Bolton Wireless Club to revive some of the simple kit which we used back in the 1980s for WideBand FM on 10 GHz.
Just as we did then, we'll be using Gunn-effect diodes to provide a few milliwatts of output direct at 10.4 GHz with simple wideband FM modulation. But we can achieve significant antenna gains with waveguide horns and modest-sized dishes at this frequency, to make contacts over tens of kilometres.
But we can now make a step forward on the receive side by converting old (broadcast) LNBs and analogue satellite receivers to demodulate the WBFM signals with much better sensitivity than the old-fashioned mixer diode in the waveguide, and the receiver bandwidth of around 20MHz means that the wobbly Gunn oscillators are now easy to tune in!
More or less the same equipment can be used for FM Amateur TeleVision too.
Here are my results on 3cm from Winter Hill so far...
| Date | Station | Location | km | Notes |
| 29-May-2011 | M0UFC/P | Werneth Low | 35 | One-way: I heard his TX (only using small horn) |
| 26-Jun-2011 | G8DTF | Boothstown | 12 | Bob's NBFM deviation sounded very quiet! |
| 26-Jun-2011 | G4JLG/P | Farnworth | 6 | I heard Dave well, but he struggled to hear me |
| 28-Jun-2011 | M0UFC/P | Werneth Low | 35 | Two-way, with Gunn diodes and small dishes |
| 7-Aug-2011 | MW1FGQ | Holywell | 62 | Stong signals both ways, using Gunn diodes and LNBs with small dishes |
| 23-Aug-2011 | M0UFC/P | Werneth Low | 35 | One-way: I heard Mark's WBFM very clearly, but he couldn't hear me with the Gunn/mixer receiver |
| 23-Aug-2011 | MW1FGQ | Holywell | 62 | Stong signals both ways, using Gunn diodes and LNBs |
| 23-Aug-2011 | G4CBW | Stoke-on-Trent | 63 | One-way: I heard a stong NBFM signal from Tony |
| 23-Aug-2011 | G8DTF | Boothstown | 12 | One-way: I managed to resolve Bob's SSB on WBFM receiver with no BFO! |
| 1-Oct-2011 | M0UFC/P | Werneth Low | 35 | One-way: I heard Mark's WBFM very clearly, but he couldn't hear me with the Amstrad LNB/tuner |
| 1-Oct-2011 | MW1FGQ | Holywell | 62 | my modulator was quite noisy |
| 26-Jun-2012 | M0UFC/P & G4JLG/P | Farnworth | 6 | With their LNB receivers our two-way NBFM QSOs were much clearer. Also 1-way with G4MVU on SSB |
| 24-Jul-2012 | M0UFC/P & G4JLG/P | Farnworth | 6 | 2x two-way QSOs |
| 5-Aug-2012 | G4JLG/P | Ashurst Beacon | 17 | Also MW1FGQ, one-way |
| 28-Aug-2012 | G4JLG/P, G0CTO/P & M0UFC/P | Farnworth | 6 | 3x two-way QSOs |
| 6-Oct-2012 | M0UFC/P | Werneth Low | 37 | very strong signal |
And much to my surprise, I won two RSGB Certificates with this kit in 2011: Runner-up in the 10GHz Open section of the October UHF event and joint winner (along with Dave G4MVU) of the Open Section of the 3cm UK Activity Contests in 2011!
Then in the spring of 2013 (thanks to a suggestion from Bob G8DTF) I bought one of the new Octagon Optima OTLSO LNBs. These incorporate a (moderately) stable PLL-synthesized LO (rather than a wobbly DRO) and so can actually be used for narrowband reception.
Although only specified down to 10.7GHz, they are still quite sensitive around 10.368 - the Amateur band being downconverted to 618MHz. So with the LNB mounted in front of my small "caravan" dish, I was able to pick up the GB3XGH beacon from Rochdale, using an RTL-SDR USB-TV stick as my 618MHz receiver.
Then a few days later I was able to receive G8DTF on CW and then on SSB, via his favourite "scattering-point" towards Manchester (although I am almost due North of Bob, I was only able to hear him when he was beaming around 105 degrees!).
If you'd like to try a sked on 3cm (narrowband, WBFM or even FM-ATV), then please get in touch.