Re: {Collins} 866A semiconductor replacement



Tom,

  This 'diode' has numerous diodes in series inside the can.  It has a
forward voltage of 28V under load, probably about 20v without a load.

  If you have a DC power supply of any kind, take the supply, and a series
resistor and take the PS ground to the diode cathode and resistor from the
PS+ to the anode.  Set this supply to 30v OR ABOVE.  Use approx 20K 1/2W
series resistor - this will put the current at 1.5Ma for 25v,  3.0Ma for 60V
etc.  You can use any handy resistor - 10k, 20k, 30k, etc.  If the resistor
gets too high the diode 'leakage current' may mess up your readings.  

  Then use your DVM to measure the VOLTAGE across the diode (while the power
is being applied).  This will be about 20-25v if the diode is good.  If you
reverse the connections to the diode you will see the full PS voltage
without a drop.

  Good luck 

Gerry
AD6MC

-----Original Message-----
From: collins-bounces+gblock=sbcglobal.net@xxxxxxxxxxxxx
[mailto:collins-bounces+gblock=sbcglobal.net@xxxxxxxxxxxxx] On Behalf Of
Dave Risik
Sent: Sunday, June 28, 2009 11:13 AM
To: thankins@xxxxxxxxx
Cc: collins@xxxxxxxxxxxxx
Subject: Re: {Collins} 866A semiconductor replacement

Its not usual that ALL will be bad... try changing the range on your meter

Dave WA3HSC

---------- Original Message ----------
From: "TH Consulting" <thankins@xxxxxxxxx>
To: <collins@xxxxxxxxxxxxx>
Subject: {Collins} 866A semiconductor replacement
Date: Sat, 27 Jun 2009 13:59:53 -0500

Hi to the list--anyone out there have any experience with plugin direct
replacement 1N2637 diodes for the MV 866A. I have 6 of them and show no
continuity using a VOM(forward or reverse). Am I overlooking something?

Tom Hankins
K0EOA


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 NETS: Tues & Thur: 3.805 MHz-2000 Central + Fri: 3.895 MHz-2000 Pacific
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