[Boatanchors] Re Why Twin Diodes In Xtal Sets?

[J Forster]

On the FM reception, it sounds like a version of a Foster-Seeley discriminator.
Basically two tanks, tuned to slightly different frequencies, fed the same RF or
IF input. Each tank output is detected and the detected signals summed.

As to using multiple diodes in series or parallel, I doubt there is much to be
gained.

Best,
-John



Duane Fischer, W8DBF wrote:

> Hello All,
>
> I have noticed that some MW and SW crystal sets from the forties and fifties
> employ a pair of detectors instead of just one. Can you please explain to me
> the reasons why and how such a circuit would work?
>
> Is there 'really' a benefit to using two?
>
> Although I have never personally come upon plans for one, I was told by an
> older Ham that two diodes were used in crystal sets that received FM. Is
> this correct? If so, what role do two diodes play in FM signal detection
> specifically?
>
> Thank you.
>
> Duane W8DBF