What is it?
 

I've inherited the device in the attached picture from my ex EKC0, MEL, Philips engineer father-in-law.
Within are two ECC81 valves. The magic eye is labelled "Power Factor". The case is very similar to another which I have with a Marconi label on it.
Any ideas?
Alan

Re: What is it?
 

Looks like a capacitor tester, but I am only guessing.
I DO like the centre punch marks on the front "panel ". I have never thought of that and have been playing with this stuff for more than 60 years DUH!!. Might also be a mesurement set for transformers/coils.


Joe

Re: What is it?
 

As Joe says a cap tester, power factor is olde English for ESR I think.

Andy.

Re: What is it?
 

Most probably a component-measuring bridge. 'Power factor' indicates it's an AC bridge. It could be for inductors, capacitors or both.

Power factor, Q, D (Dissipation factor), Lossiness, Equivalent Series Resistance, Equivalent Parallel Resistance are all different ways of expressing the same thing, power loss in a reactive component which should, ideally, be lossless. Once you know any one, you can convert it to any of the others.

Different industries and fields of electrical science prefer one version over the others, because it makes something easier or more obvious in that field, but it's still all the same thing expressed in different ways.

Power factor is heavily used in power distribution. Q in the RF world.

A bridge would have one pot for nulling to find the reactive component L or C, and a second pot to find the resistive component. Only by nulling on both pots alternately do you find the deepest null.

David

Re: What is it?
 

I would suggest, that the bottom control with scale, is a variable cap as its travel is only 180 degrees. Yes I know there are pots that do this as well, it still adds up to a null control.
I would be VERY interested to see the circuit. I imagine one valve ( two halves ) will be an oscillator and buffer to reduce impedance, the second pair of triodes will drive the null on the magic eye. Most magic eyes are rather lazy when it comes to sensitivity after all.

Just thinking out while typring.

Joe

Re: What is it?
 

Thanks for your suggestions gentlemen. It looks like it is a capacitance bridge. I searched the internet and could find nothing similar, which rather surprised me.
As suggested, the knob at the bottom is a variable capacitor. Sorry Joe but I can't trace the circuit just now - I'm supposed to be house clearing not playing with the toys.

The power lead is terminated in a 3 round pin plug. Before plugging in I'd better open it up again to make sure the supply is 240v and not DC.

Alan

Re: What is it?
 

Mind your fingers on those terminals, they may have something like 150V on them normally albeit at low current and if there's an insulation setting perhaps more.

Andrew