[1000mp] S-Meter Adjust Worked and what about the "PIN Diode Mod

[Bill Tippett]

 From W8JI at http://www.w8ji.com/receivers.htm

Receiver Myths




PIN Diode Mods

Save your money. PIN diode replacement never has changed performance in any 
receiver I've listened to or measured. PIN diode mods don't change 
distortion, blocking, noise, or any other parameter. A normal signal diode 
with proper bias is just as good.

PIN diodes function as "RF switches" or "linear RF resistors" only when the 
carrier lifetime exceeds the period of an RF cycle by a large margin. Most 
of the diodes used in PIN mods do not have long enough carrier lifetime to 
even behave like a low-distortion linear resistance, let along a pure 
switch. They really aren't any better than manufacturers stock diodes, with 
the PIN diodes barely being linear at 30MHz let alone at 455kHz. The whole 
"PIN diode thing" would be laughable if it wasn't costing people money!

If you have even measured a real difference, please e-mail and tell me what 
radio it was and what the test conditions were. If you are only going by 
emotion or feeling, don't bother reporting that. If I spent several hours 
and/or a few hundred dollars changing diodes and could not A-B the change, 
I'd probably think things got better also.

         Sherwood Engineering posted results of an IC-781 with PIN diode 
mod which
agrees with W8JI and Inrad.  2 kHz IMD decreased from 78 dB to 72 dB after 
the mod:

http://www.sherweng.com/table.html

                                         73,  Bill  W4ZV