I ordered a whole bunch of diodes for Jameco a while back and in the kit there 
was allot of 1N270.

I do think they are in production though, maybe not as they use to be.
I was looking for the best demodulation diode in the ARRL handbook and Schottky 
types were the most sensitive.

The one I wanted was rated at 0.3 volt forward minimum at 0.001 A and this 
happens to be the 1N270 but there is a new part type that is rated the same. it 
is 5082-2835 and next to that is the 1N6263.  The later is rated 0.4v @ 0.001 A

What is unusual, which I never considered before is the rate of change of 
voltage and current.  The impedance then is lower than you would expect.

I had an idea the folk could buy a few low noise amps, like those used inline 
with coax, maybe even some of the wide band TV antenna models and use them with 
a simple QSD demodulator as the front end section for some home made gain 
sections.  The TV preamps are not exactly the ones I was thinking of, who knows 
the noise level of them?  But they are cheap at Radio Shack.

I was looking at the AD797 low noise amp, but have not seen data for use in the 
rf range above 1 MHz as a preamp.  These are rated low noise.  I am kind of 
doubting it now but I am looking at it stiil.

Anyways I can still use Fets as amps.
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