ID this valve.
 

A power-rectifier, on a 4-pin base with the pins bifurcated, 5V seems to work well as heater voltage.

Indirectly--heated cathodes but with the cathodes strapped to the heaters, which sort-of hints that it is an analog for a directly-heated precursor.

There's a little 'nub' on the bakelite base adjacent to one of the four pins - presumably to give guidance whrn plugging it into its socket.

Intriguingly - the two anode-assemblies are rotationally offset so that they do not face directly towards each-other; this is clearly an attempt to stop them radiating the inevitable anode-dissipation-Watts at each-other.

Re: ID this valve.
 

45-1U:

http://www.r-type.org/exhib/aad0016.htm

?

Re: ID this valve.
 

5U4 with a weird base.

Joe

Re: ID this valve.
 

I think you're probably right, and that I overdrove the filaments at 5V.

It comes from a push-pull audio amp using a pair of KT66.

Re: ID this valve.
 

I've mentioned this before regarding these old B4 valves, but there were no comments on it, so I guess nobody knows. My own findings seem to indicate that it's found on very old valves made around 1929 - unless anyone knows any different?

Re: ID this valve.
 

I've never come across a valve with that little nub before. I guess it's to make 'blind' insertion into the base a bit easier by helping you know where oin 1 is.

Re: ID this valve.
 

Cossor valves do tend to become anonymous as they mature because the original ID was often on a stuck-on paper label which is outlasted by the valve itself.

Martin

Re: ID this valve.
 

I have some very early MOV triodes (ML4 etc.) with the same type of base with the locating nub.

Given that this is an indirectly heated rectifier (so not a 5U4) I would suggest that it could be a very early specimen of the MOV type MU12 or MU14.

Leon.

Re: ID this valve.
 

Yes I've often wondered what the pip was for, I have several 4 & 5 pin valves with this feature, I wondered if it was for the radio servicing chaps, the back of a radio can be very dark to see what your doing, so the pip can easily be used to work out the pin biasing in conjunction with feeling for the screwhead or rivet securing the valve socket in the chassis.

Nearly all 4/5 bases I've come across have the same orientation & if it's wrong first time just rotate 180, no forcing/bent pins.

Many noval valves use that idea, having the widest pin gap facing one of the mounting flanges, of course more difficult on skirted bases but still doable,.