An interesting old Coil

[AlanBeckett]

To continue.

Finally 2nd HF - the RH one:-

           

I freely admit that I've failed abjectly to track down the 'Raleigh PM', or should it be 'PM Raleigh'.
Come on Lawrence and Alan, you always turn out to expert in these matters

The Aerial one appears to be quite straightforward, apart from deciding which way round it should be. Is the bottom Winding for Grid or Aerial.
The 1st HF is even more obscure. Clearly te 200uH is the tuned Winding, but why is the other Coil Tapped? or is it really two Coils in Series?
The Second HF, which I assume should include a Reaction Winding, I don't understand at all.

I should have said by the way that you can't see all the Windings from the outside. If you look at the second Picture above there's another Former inside

So, come on Gents, what was the 'Raleigh PM' or 'PM Raleigh.

Alan

[pwdrive]

Mullard Raleigh PM...Blueprint here:

http://www.ebay.co.uk/itm/Mullard-Receiv...1803871174

Lawrence.

[AlanBeckett]

You really are a Genius young Lawrence.
But Ooh, Aaar, Eeeeh - that's a good Price.
Do you think I could Reverse Engineer it from the Picture?


Alan

[pwdrive]

Alan, If you could do some kind of screen grab then maybe it could be reverse engineered?

Lawrence

[Refugee]

Screen grabs are very easy to do.

[Alan Douglas]

I don't think I've ever seen an issue of Radio for the Million.

[unrealdave]

Here are a few of the coils I have collected – the one on the set is a Formo two range tuner and I am currently building a set with it with my mate – the circuit is pictured as well, and also an original Formo article from 1929.
 
I have a good range of the dimic coils but unfortunately no holder – if anyone comes across one please let me know.
 
The last two pics are of a cotton covered home built one (I think) that I might use with the F2 Ferranti transformer as it would go well.

[unrealdave]

I like the little SW coils home made on old valve base’s.

[unrealdave]

I know it’s a different type of coil but it’s really cool and it works.  It’s a signal loose coupler tuning coil I got from America.

Apparently this has great 'Q'

[AlanBeckett]

That certainly looks like the same Formo Coil as mine. So there should be an hf one to match.n I've pinched the Circuit
Well, I have another Formo Coil, in a fairly disastrous condition, which I haven't documented yet.
I'll get on with it.

Alan