Permeability Tuning

[pwdrive]

Have added the 1932 Paper on this subject to the Archives (Books & Literature Section)

Lawrence.

[Radio Fixer]

Only ever come across it once on a US Truetone D2610 from 1940. I think it was mainly used on car radios

   

What did the radio look like? Lot better than a DAC90 to me

   

Gary

[Mark Hennessy]

Gorler made FM tuners that used it - I've seen them in the Hacker Mayflower and RP18 Sovereign. Outside of that, I'd agree that it seems to be most commonly encountered in car radios...

[Joe]

Bush VHFxx sets use it.

- Joe

[AlanBeckett]

So do the Pye VHF2D and 3D, but only on VHF.

Alan

[AlanBeckett]

Oddly, the Fenman I doesn't (on VHF), but the Fenman II and the HFT111 do. I don't know about the HFT113 but I think it does.
Was it down to economics or performance? It can't be size 'cause there's plenty of room in the Fenman I.

Alan

[Mark Hennessy]

A lot of FM sets I've looked at have 3 tuning capacitors, i.e. 2 tuned RF stages. All the permeability-tuned sets I've seen only have 2 coils, so only one tuned RF stage. I could imagine that the mechanical issues of having 3 coils and the bit of string joining the cores could be challenging to say the least.

So perhaps on these grounds capacitor-tuned sets could offer better performance, all other things being equal?

[Paul_RK]

Dansette's little TRG45 battery portable radiogram from 1960 is the only domestic AM instance that springs to mind. Quite surprised me to find anything at all technically unusual in a Dansette product, there's not generally much sign that they had a lot of R&D going on, and their radios were early adopters of Mullard modules.

[AlanBeckett]

The Pye HFT111 has tripple Permiability tuning on VHF, but only a double gang on am.
It looks as though they meant it to work.
It's in the shed, two acually, and an HFT113

Alan

       

[pwdrive]

So, mainly VHF then and car radios.
The VFO on the Collins R390A used permeability tuning, quite a precise affair in that receiver.

Lawrence.