Small two band 6 and 2 meter amplifier..

VK3ZL Amplifiers
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VK3ZL
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Posts: 40
Joined: Wed Sep 14, 2011 11:34 am

Small two band 6 and 2 meter amplifier..

Post by VK3ZL » Mon Nov 11, 2013 4:08 pm

Hi all..I have been trying to get around to building a couple of moderate powered amplifiers for my own use but time always seems to pass doing other amplifier jobs...I finally decided to start on something as I knew that was the only way I would ever get something done for myself....After a lot of thought I decided to build two separate amplifiers into the one box with a matching power supply box...

As I am infrequent on the VHF bands I needed something fairly simple that would give me about 300 watts on both bands...I have settled on the Russian GS-9B triode for each amplifier...These tubes are the same size and appearance as the GI-7Bt tube but have a 300 watt anode dissipation and only 1.2 amp filament draw..I built a 2 x GS-9B 2 meter amplifier a while back for a ham and he has been delighted with it...These tubes only cost $15 each from Ukraine so they are more than value for the price..

I have progressed as far as building up the amplifier case and put together both RF decks side by side with a divider..The 6 meter amplifier is standard, Pi-L tank circuit...The 2 meter amplifier uses a grounded 1/4 wavelength plate line..The work is fitting up the tune and load controls etc but it is now complete..

Cooling the tubes is done using two 24 volt 80mm muffin fans...The air will blow into the amplifier RF deck and exit through the tube coolers and Teflon chimneys fitted to the top cover...The air from both fans pressurise both amplifier compartments with a screen in the divider..When operating one amplifier I can cover the unused air outlet so that the tube in use gets full pressure from both fans..As the tube will only be dissipating 2-300 watts there will be ample air for cooling..I only use CW or SSB..

Pics show the RF deck progress to date...I am gradually getting a bit done on this project as time allows..I will post further progress as I can..

Enjoy....Bob..VK3ZL..
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VK3ZL
Forum Novice
Posts: 40
Joined: Wed Sep 14, 2011 11:34 am

Re: Small two band 6 and 2 meter amplifier..

Post by VK3ZL » Mon Nov 11, 2013 4:21 pm

I forgot to add the pics of the original RF deck tray..

Bob..VK3ZL..
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HPIM5872.JPG
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