10GHz - getting ready....

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radiogareth
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Joined: Wed Jan 06, 2016 9:46 am

Re: 10GHz - getting ready....

Post by radiogareth » Wed May 11, 2022 5:51 pm

Thanks Dave, .....yes, got a bit lost on that one, was thinking of the doughnut of radiation around the 1/4 wave....

On Noels suggestion I'm culling an old LNB and isolating one of the pre-amps.
The coupling capacitor between the first two stages is a 220pF (larger than I expected). I culled another cap from the DRO oscillator coupling into the mixer, that one was only 1pF.
1pF is about 15 ohms at 10.3GHz, so I'd guess that it doesn't matter. I'm using this one to isolate the gate -ve bias from possible shorting out by a DC antenna, not that the G3PHO is a DC antenna, but one of my WG16 launchers is.
The other one (220 pF) is of course fractional ohms at 10.3G, and not many of them either.
I'll give it a RX test tomorrow early and see if it helps.
A single dish solution would be lovely. I've even got a change-over relay rated to 18GHz and 12V.
Gareth

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