Valve top cap voltages.

[Hartley118]

I still find that the old maxim “keep one hand in your pocket” is a useful safety precaution.

Martin

[Andrew B]

Originally Posted by John M0GLN

I've got a couple of RG3/1250 valve rectifiers which are good for 13000PIV at 1.25A.

I have a couple of RR3 1250A's that I posted here http://www.r-type.org/exhib/aag0135.htm I wonder what equipment they were used in? who needs 13Kw+ of high voltage DC.

[John M0GLN]

Originally Posted by Andrew B

I have a couple of RR3 1250A's that I posted here http://www.r-type.org/exhib/aag0135.htm I wonder what equipment they were used in? who needs 13Kw+ of high voltage DC.

Probably going off topic a bit, or a lot, but as you have asked this is the very piece of equipment, a 10kW induction furnace, I'm on the right with the face shield on, taken in the early 60's at Mullard Magnetic Components Southport, we are melting some special steel for swaging hammers for Mullard Blackburn Works, on the right behind the grill you can see one of the 8 rectifiers and on the left 2 water cooled triodes.

[G6Tanuki]

Originally Posted by Dave757

Hi,

Came across a 7193 triode with 2 top caps - One grid and the other anode.

I understand the reason, but why have what appear to be identical topcaps
for both.

I'm guessing that the circuitry associated with them would have had
such short connections that you couldn't misconnect them.

Yes, these sorts of 'horned Devil' triodes were used in VHF superregenerative transmitter/receivers around WWII - the spigot on the Octal base indexed the orientation of the valve into its socket and the grid/anode leads to the twin top-caps were - of necessity to minimise losses and so have a chance of working at the required high frequencies - very short so there was no chance of them being transposed.

The CV6/DET20/VR135 was used in the rather-less-than-successful WS19 "B"-set operating around 225-235MHz; it also had a slightly more-successful role in various similar-era airborne Radars.

http://www.r-type.org/exhib/aac0111.htm

In the immediate post-WWII era, when there were loads of Government-surplus valves on the market, the 'double-top-cap' triodes were often repurposed to do service in things like the first-stage of audio-amplifiers.