Author Topic: So, a rash and crazy purchase, or a jewel of a 2 metre amp in the making?  (Read 303 times)

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Offline Chris Wilson

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I would normally have  been in the pub, not buying stuff I almost certainly do not need off the Internet, but the hostelries are shut down here in the UK because of the Corona Virus outbreak. Whatever, my finger stopped wavering and hovering and a last moment bid was made resulting in this obvious, if incomplete, labour of love by a German ham, now sadly deceased, becoming mine. A two tube, 2 metre amp using a pair of G17B's with internal PSU.

I have not picked it up yet, but would welcome any comments as to whether it may have been from a known design, or, if as I suspect, it was a unique but unfinished labour of love by a gentleman with excellent machine shop skills and a desire to produce something of shiny machined alloy beauty? Will it ever work, or will I be left with an ornament that will become testament to too much time on my hands browsing web sites during the virus lock down? ;)

The 11 photos can be seen in the Zip file at http://www.chriswilson.tv/2m-amp.zip
Best regards,

                 Chris Wilson.
 

Offline M0HZH

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Those are almost certainly GI-7B tubes, good for about 250W each. Very popular russian triode about 20 years ago (probably due to a large volume of Cold War new old stock being dumped in the market), the internet is full of designs using them. Looks like the guy most likely removed the standard anode heatsinks (or used the GI-70B version that comes without heatsinks) and used his own.
 
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Offline Nuno_pt

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Well, they are GI7b with a modified heatsink, soon as I put my eyes on the schematic, I saw that I recognize that drawing, it's made by YU1AW you can see that particular on here < https://www.qsl.net/yu1aw/VHF_PA/shema%202xGI7B%202m%20LB.gif > or more from here < https://www.qsl.net/yu1aw/Misc/engl.htm >
Nuno
CT2IRY
 
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Offline Chris Wilson

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They are definitely GI7B valves with the stock anode coolers removed and a complex custom one made and fitted. The amp came with some documentation suggesting the deceased builder might have been one Peter Jacobs DK2EU. There is no built safety circuitry in it, but there are some components like switches and LED's that seem to have been added to work with safety stuff. I may use a commercial triode safety board, I have some unbuilt ones from GM3SEK : http://www.ifwtech.co.uk/g3sek/boards/triode/triode-1.htm

Thanks for the replies.
Best regards,

                 Chris Wilson.
 


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