[Amps] Checking Filament Voltage

[Roger Parsons]

Many thanks for many replies received both direct and via the reflector. However, I'm not sure that I can reach a definitive conclusion!

The tube in question is a 4CX1500A - purely because I happen to have one and a base - so the filament current is quite significant. I am concerned about voltage loss on the fairly long connections between transformer and tube.


The reason for wanting to do this is that the design of the (existing) cabinet (and my ideosyncratic circuitry) make it very difficult indeed to change filament voltage when all is assembled, except over a small adjustment range.
In most amateur amplifiers the filament power and blower are applied simultaneously so there must a short period before cooling starts.That's my theory anyway...

I am quite seduced by the concept of having a fan blowing on the base of the tube whilst I do the test, and I think I will try that. Whilst I may have to make several repeats, each test should only take a few 
seconds. 

Thanks again for the help.

73 Roger

VE3ZI