[ForSale-Swap] WTB: Diode for AN/URM-120 Power Meter

[Bob Stein]

Robin Midgett wrote:
> Hi,
> Several of you responded with helpful information concerning my 
> problematic URM-120 power meter; thank you very much.
> Now I'd like to find a source for the diode used in the meter; I have 
> one in the 2-30MC insert that is shorted. I also need the insulating 
> washer that goes on the diode (lost it in the carpet...doh!)
> The number on the shorted diode I have is 100507, followed by 8338 (date 
> code 38th week of 1983?), and the word MICROWAVE.
> 
> 
> Thanks,
> Robin Midgett KB4IDC
> VHF+ Glutton
> 
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Robin, the diode that you have was manufactured by Microwave 
Associates.  The number 100507 probably indicates that it was a 1N21B 
selected to meet a customer's spec.  If you have a Sierra 270A-30 
plugin (not one manufactured by Struthers or Douglas Microwave), the 
Sierra stock number for that diode is 9105000007, and the Dwg or Mfr. 
No. (probably Sierra's spec control dwg) is SS-13154-1-2.  The catch 
is that Sierra is either out of business or has been absorbed by some 
other company, which has happened at least twice before - once by 
Teledyne and once by Philco-Ford.

You should understand that if you do find a diode which will give you 
a 50-watt full-scale meter reading, you will have to recalibrate the 
plugin on the other power ranges.  The second catch, as I indicated in 
my previous email, is finding a diode which will give a full-scale 
meter reading.  I have about two dozen 1N21Bs, and I know some of them 
are usable in the plugin, but I have no idea at this time which ones 
make the grade.

Bob, W6NBI