Manganin Wire

[pwdrive]

I have found a reference that said Manganin wire was sometimes used for the feedback winding in regenerative receivers to improve the smoothness of regeneration, has anyone tried it, was that ever used in a production receiver?


The reference was found in Babani's Coil Design & Construction Manual.

Lawrence.

[AlanBeckett]

Why should having a near constant Resistance over a wide Temperature Range improve the 'Smoothness of Regeneration'?
Sounds like Snake Oil to me unless there's some other property of the Alloy that's important.

Alan

[pwdrive]

I'm not sure either Alan, possibly the damping effect of its self resistance? don't know anything about it but it's mentioned here:

https://archive.org/stream/CoilDesignCon...1/mode/2up

Lawrence.

[pwdrive]

A bit more digging revealed this radio, a Cossor 464, not a regen but a superhet, however the SW oscillator feedback coil (L9) appears to be made from resistance wire as the value for L9's resistance is given as 29.5 ohms, according to an old thread on UKVRR the resistance value quoted it is not a misprint, the poster seemed to confirm that the feedback coil (L9) was indeed made of resistance wire, L9 is part of the osc coil on SW, the other oscillator feedback coils (MW & LW) appear to be made of copper.

Link to the Cossor manual:

http://www.radiomanuals.info/information.../s0775.pdf

Link to the UKVRR thread:

http://www.vintage-radio.net/forum/showt...p?t=103145

Lawrence.

[Alan Douglas]

Resistance wire was sometimes used in 1920s RF transformers to broaden the response. An external resistor of course would do the same thing.

[Ed_Dinning]

Some of the Wearite P range had the one of the oscillator coil windings in resistance wire to reduce its Q.

Ed

[AlanBeckett]

Perhaps the distributed resistance was an advantage over simply slapping a Resistor across the Winding. It may also have been cheaper.

Alan.

[Radio Fixer]

But back in the 20's you didn't just take a resistor of the shelf and wire it in. If it were across the coil, rather than being part of the winding it would have needed to be upper K Ohm in value. So possibly a glass tube device and then a holder.

As a point of interest, the LW and MW feedback coils in the bandpass filter of the Philips D57 I'm working on, were 450 and 260 Ohms. Not resistance wire but the finest enamel gauge. Rewound for me by Mike B and working again.

Gary

[Alan Douglas]

That's right; there were no low-value carbon resistors in the 1920s. If you had to use wire anyway, it might as well be wound into the coil itself.