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Author Topic: 5W amp for 630m from G0MRF  (Read 1112 times)

AE5X

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5W amp for 630m from G0MRF
« on: October 08, 2019, 08:02:32 AM »

I just finished building this inexpensive amplifier kit from David G0MRF. It was easy to build/align and does what he says it'll do:

https://ae5x.blogspot.com/2019/10/a-low-cost-set-up-for-630m-wspr.html

73,

John AE5X
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VK6HP

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RE: 5W amp for 630m from G0MRF
« Reply #1 on: October 09, 2019, 01:12:22 AM »

John

I think you'll be very happy with the G0MRF 5 W amplifier.  I bought one as a quick way of getting a few watts from my TS-890S or TS-590S on 630 m.  I ran it as a QRP final (5W) for a few weeks and found it to be quite clean, and tolerant of mismatches.  With 5 W I had many WSPR spots from New Zealand, which is more than 5000 km from Perth.  David's kit was complete and, knowing that I was going to push it pretty hard for a while, I took care to properly heatsink the final transistor to a diecast box.  I've not found any issue with overheating.

These days the 5 W amplifier is heavily padded back in gain to drive my homebrew 1 FET linear (100 W).  The higher power of course gets far more hits and has allowed some JT9 two-way QSOs.  I'm still evaluating my 630 m system and the band itself and, over summer, I'll either package up the existing system or do a higher power amplifier driven directly from the ~0 dBm "DRV" output from the Kenwood transceivers.  (David does also sell a 300 W non-linear kit which looks well thought out.  It does however pre-suppose a doubled-frequency drive which is a touch inelegant from my starting point).

Good luck with your 630 m station.  (I've put a few details of my entry-level system on my QRZ page if you happen to be interested).

73, Peter.
« Last Edit: October 09, 2019, 01:17:32 AM by VK6HP »
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AE5X

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RE: 5W amp for 630m from G0MRF
« Reply #2 on: October 09, 2019, 07:13:27 AM »

Thanks for the info and the interesting write-up on your qrz.com page Peter. We have similar antennas for 630 and the same problem - high noise on receive. I may do some experimenting with a rx loop over the next few months. It's disappointing to be heard by DX but not be able to hear them on 630m.

73,
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AE5X

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Re: 5W amp for 630m from G0MRF
« Reply #3 on: November 01, 2019, 04:23:45 AM »

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