VT61A - Dalek valve!
 

Rummaging through my spares I came across this somewhat strange, 'Dalek' looking valve. Apparently it's a VT61A transmitting double triode (info from valve museum) designed for use up to 150 MHz. It was made by Rogers of Canada and carries the Air Ministry markings. The VT prefix is an Air Force designation, also on the envelope is the old stores code of 10E/142. The original VT61 is on a UX7 American base, but for the VT61A the valve is mounted on a B5 base.

This one has 'A M' and a crown above that engraved on the base. Also 10E/142b.

I was just wondering if it had any memories for anyone and if it has a use these days in vintage equipment? I wouldn't have thought so.

Re: VT61A - Dalek valve!
 

Used in WW2 aircraft IFF equipment.

Re: VT61A - Dalek valve!
 

More of the horned beast than a Dalek, just think it was things like that that won WWII for us. A forgotten history and (well I can't find one) not in any war history books.

Re: VT61A - Dalek valve!
 

ISTR assembling an RSC 'high gain' audio amplifier kit in the 1950s which used a couple of VT61s in parallel push pull as its output stage. Rather pretty valves with those 'rabbit ears'! I believe the push-pull pair was claimed to give 5 watts of audio.

I think the amplifier also included a couple of VR65s (SP61s)

Martin

Re: VT61A - Dalek valve!
 

Not a very good picture, but two can be seen in this view of the IFF Mk2 unit.

Andy

Re: VT61A - Dalek valve!
 

Had some NOS similar to these, half a century ago, 2C34 or RK34. I built a PP amp using one, which worked but not very well. A better approach to amp design might prove interesting.

Re: VT61A - Dalek valve!
 

They fitted into the same technical-space as the similar-era CV6/CV1135/CV2920/DET20/VR135 which was used in the WS19 "B-set" superregen transceiver around 220MHz - it was essentially a 6J5 triode with the grid and anode brought-out to top-caps to make their involvement in VHF tuned-circuits a bit easier.

The VT61A would have been ideal for use in a 'tuned lines' push-pull low-power VHF transmitter circuit.