Sunday, March 11, 2007

Whats a QQVO3-20A?

This amazing valve, which looks a little strange, was a wonderful device for VHF and UHF transmitters. Driven correctly, it would provide 20w output on 144mhz and 10w output on 432mhz. The device had twin anodes which was great for balanced tuned circuits. It's 'big brother' was the QQVO6-40A which would provide 50w+ output, but needed a higher voltage. It's little brother was the QQVO3-10 which looked like a conventional valve.

My first 70cm transverter used two of these QQVO3-20 devices, one to 'triple' the frequency from the 144mhz input to 432mhz and the other to provide the power output.

The base was made of ceramic and quite difficult to obtain. The transverter was Grid Modulated for Amateur Television Transmissions and worked quite well! Quite a bit of metal work was needed to build the transvertor, including tapped brass anode and grid lines. It was tuned with a PTFE square which passed between the anode lines.

Now, I had some of these devices in a box in my loft, but I can't find them...surely I didn't throw them away? I'm still looking!

1 comment:

David Davis said...

Hope you find them, OM! If you need one or two, I think I have (NOS) a couple, never used, open to offers!

73 de M3LBG
(David Davis)