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Old 17th Nov 2005, 7:48 pm   #2
YC-156
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Join Date: May 2005
Location: Aarhus, Denmark
Posts: 281
Default Re: Homebrew transmitter project (Frank vs. Oskar :) )

Hi Oskar and the group,

As Oskar just mentioned, then I will also be participating in this little, informal 'build-off', or perhaps 'build-along' is a more appropriate description.

My project is something I have wanted to start constructing for a while, but so far have lacked a good excuse. The design details are not yet clear, even to myself, but hopefully I will have that sorted out before too long. What is known though, is that my aim is a valve based Morse code (CW) transmitter with at least 250W of carrier power at the antenna connector. I may make this a tri-band project (14, 21 and 28MHz), but a single band 28MHz TX is also being considered.

I could choose to hurl a modern transmitter valve or two like the 4CX250B at the project and be done with it, but I much prefer the old school look of clear glass bottles and lots of copper piping. So I will use something else from my stash...

Attached below are a few snapshots of the core chassis and the HT transformer. For a start my project will focus on actually testing many of the critical components. Those being mainly said HT transformer, the output valves I'd like to use and the filament transformer for those. I only need a single output valve for my choosen power level, but would like to make sure I've got a working spare.

Hopefully all the components will work. If not, then it will be time to come up with a plan B.

Parts of today was spent making the HT power supply subassembly, needed for testing the HT transformer. I only need to fit another 20 diodes, then it will be time to run up the variac.

Timeframe to completion: Unknown.

Frank N.
Attached Thumbnails
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ID:	2007  
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