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

[John L Merrill]

Bill:
Will anything ever top an Orion, HI?

John N1JM


On Oct 13, 2004, at 1:09 PM, Bill Tippett wrote:

>
>
> 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
>
>
> _______________________________________________
> 1000mp mailing list
> 1000mp at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/1000mp

---