Saturday, 17 September 2022

Don't shout - WSPR

Homebrew WSPR TX using the brilliant open source code by Harry from Zachtek.
If you want the best, buy from Harry,  https://www.zachtek.com/

I tweaked Harry's code to suit my particular setup(s), initially with a scratchbuilt, single band Tx with GPS - about 200mW out on 40 metres on a 9v DC supply.



I then made a multiband unit using modules from QRP-Labs, including the Arduino shield, si5351 OCXO, relay switch kit and assorted LPF's that all plug into an Arduino UNO.
The OCXO si5351 makes it so much more stable and once warmed up, it doesn't drift - I must try it on 144MHz sometime...



Running at 9v DC in gives an easy 200mW+ on multiple bands, in my case, 4 bands (10, 15, 20 & 40).
It is easily programmed by Harry's excellent Windows software and once the initial settings are done, it needs no further configuration as all important info is taken from the GPS (time, locator etc).
It only needs reconfiguring if you change bands/LPF.




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2 comments:

  1. Unknown17 September 2022 at 09:45

    Hi there, saw your post to the G-QRP list on my WSPR beacon in Sprat. Our projects are very similar. The Zachtek code saved me a lot of time, and my beacon worked pretty much first time, once I stripped out some unnecessary memory-hogging features.
    Your work to make yours cover four bands with the Qrplabs filters is well done and gives you a much improved indication of propagation from your home station.

    All the best, 73, Paul VK3HN.

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  2. G4ZAL17 September 2022 at 14:19

    Hi Paul,
    Thanks for your info in SPRAT and for sure, Harry's code saved me a ton of work too!
    I do use Harry's Windows app to set mine up.
    73
    Nigel, G4ZAL

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