Here is a link to the obligatory HeyWhatsThat site profiler so you can check our radio horizon for your QTH…
As well as our usual operation on HF, this year’s trip to Mull will see us active on 10GHz (3cm) – a first-time activation for IO66 square. Today, John G4BAO, Rob M0VFC and Gavin M1BXF tested the kit that John’s been busy building – and it all worked!
The setup is an FT-817 as the driver, DB6NT transverter locked to a 10MHz GPS disciplined oscillator, 10W PA feeding a dual 10/24GHz feed to a 60cm ex-Sky dish (about 5W of transmit power actually makes it as far as the feedpoint of the dish). The transverter and PA are mounted at the top of mast along with the dish, so power, 10MHz and 144MHz all run down to the van.
John began by aligning the dish against the nearby GB3CAM beacon – a fantastic signal, even with a screwdriver as the antenna – before we mounted it on Flossie’s mast for some more realistic tests.
G4BAO aligning the 10GHz dish
We enjoyed QSOs with G4CBW (IO83ub), G4KUX (IO94bp, our best DX at over 300km), G4BEL (JO02bi… OK, not such an impressive distance but great to chat!) and G4LRP (IO93ho). Bob, G8DTF heard us, but sadly we didn’t complete a QSO – our receive not helped by us having to beam straight at a rather noisy comms site in his direction!
If you think 10GHz is all about line-of-sight contacts between hilltops, and wide-band FM or inaudible signals, think again – here’s a short video of parts of a couple of today’s contacts to give you a flavour of the higher microwave bands:
And if I didn’t need to convince you of that, because you’re already QRV on 10GHz and would like a sked while we’re on Mull at the start of May, let us know – we’d be delighted to try and work you.
So I guess two are worth two thousand.
Oh and by the way my 125MHz Thruline reads 1dB low at 144MHz so it’s nearer 650 Watts, for 17 Watts in.
To paraphrase Chief Brody in that wonderful scene in “Jaws”
“I think we need a bigger slug”
I’ve nearly finished the first 800Watt 144MHz SSPA. I did the combiner extensions today…
(You can get the idea from the pictures.)
…and did some basic metalwork:
Just have to connect it all up and go for it!
Anyone got a 1kW 144MHz Bird thruline element I can borrow? I only have a 500Watt 50-125MHz one.
73
John G4BAO
Really I can!
Checked out the other three 144MHz band III 400W PA conversions today, all going well. Just one scary moment when a tantalum electrolytic exploded, but no major Damage, just a bit smelly.
Had a look at the combiner as well and worked out how to split it and move it down to 144MHz, but I need some quarter inch 75 0hm PTFE cable (RG302) to do the output combiner; I don’t think my RG179 will take 800Watts! Can anyone help?
73,
John
Those who follow @g4bao will know that last week I checked out the first of our modified Band III 400Watt modules on 144MHz. It produces a mouth-watering (and linear) 400Watts PEP with 10 Watts in, and has “a bit to spare” (No Gavin, that does not mean we can overdrive it and blow it up!)
Today, I modified the other three modules and plan to check them out tomorrow or Monday. I then have to look at producing two pairs of “two in to one” RF splitters and combiners from the pair of “four in to one” units that came with the original 1500W 4-bay amplifier. Watch this space for progress.
The 10GHz system has been checked out in the workshop and is ready to air test. Currently it is sitting on a tripod in my garage. The current plan is to take it out in Flossie next Saturday lunchtime and run it up on air. To this end, we need two runs of RG58, one BNC to BNC and one BNC to N plus enough decent 12V cable to go from the van to the top of the mast to ensure that we still have at least 13 Volts up top when it’s taking 10 Amps.
We have already been asked for 10GHz skeds by stations in three DXCC call areas, with promises of activity from G, GM and GI, all this before we’ve done any publicity in the Microwave fraternity. Contact john@g4bao.com if you would like to arrange a sked on 10GHz. Talk back will be on 144.185MHz and Internet permitting, via ON4KST.
73
John