On 1/9/07 10:44 AM, in article , "Michael Black"
wrote:

Stan Barr ) writes:
On Mon, 08 Jan 2007 17:10:25 -0500, Chuck Harris

wrote:
Scott Dorsey wrote:
In article ,

Any reason why a 1N4007 wouldn't be happy in there?

Well, yes. When functioning as a demodulator, the diodes take the
IF frequency (455KHz), and the BFO frequency (453.65/456.35KHz), and
make audio. When functioning as a modulator, the diodes take the
audio, and the BFO frequency, and make modulated IF.

A 1N4007 cannot switch at even audio rates, let alone at 455KHz.

You could always try a "vaccuum state" diode such as a 6AL5...

Of course, Collins likely had a good reason for using solid state
diodes there.

Far lower current consumption would be one thing.

The semiconductor diodes also make it smaller.

But also balance. I'm sure it's far easier to keep a balanced modulator
balanced when using semiconductor diodes than two tubes each supplying
two diodes.

Michael VE2BVW



If you were to use any tubes at all, it would be best to use one tube akin
to the 6be6, hang the oscillator and the product detector ckts on it, and
have the advantage of getting conversion gain instead of loss.

Don