Recommendations please.

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M5TXJ
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Joined: Wed Jul 05, 2017 8:34 pm

Recommendations please.

Post by M5TXJ » Thu Aug 18, 2022 12:12 pm

Hi all,

At last, I was hoping to join the QO-100 Net this evening but of course the Gremlins have struck. The TX line up is Pluto - SPF5189Z - Chinese 400-4GHz amp - Nokia module, the Chinese amp is dead anywhere above 1.5GHz.
Can anyone recommend a suitable replacement that isn't going to a) take months to arrive, b) cost an arm and a leg).

73 Dave.
...are you sure I can't use a pair of 813's?... :shock:

g0mjw
Posts: 2329
Joined: Sat Sep 20, 2014 9:15 am

Re: Recommendations please.

Post by g0mjw » Thu Aug 18, 2022 12:28 pm

You might try fixing the amplifier, these PAs sometimes have the wrong parts fitted. Perhaps post a picture? I would suspect the RFC and the coupling capacitors.

Otherwise, the Amsat-UK amplifier by G0MRF is a good choice. Here is the kit.

https://shop.amsat-uk.org/Filtered_S_Ba ... 51527.aspx

Mike

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

Re: Recommendations please.

Post by radiogareth » Thu Aug 18, 2022 12:36 pm

I'd second Mike, I have used one of the Amsat amps since the beginning. It goes Pluto (at -10-15dB) into the Amsat amp and then into a Nokia (3 stages from memory...). That has lots of gain - there are many different versions.
Gareth

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M5TXJ
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Re: Recommendations please.

Post by M5TXJ » Thu Aug 18, 2022 12:51 pm

Thanks Mike, Gareth.

I'm on the case!

Bypassing the amp I'm getting about 1.5W and can just see my signal on the downlink, looking promising.

73 Dave.
...are you sure I can't use a pair of 813's?... :shock:

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