[Collins] 516F-2 power supply Diode

[Gerald]

On Mon, 2005-07-04 at 09:09 -0400, Cam and Juli Hedrick wrote:
> Can I use a 1N5008 to replace CR1, I have that one in my parts supply.
> Mouser will get my order for the caps, so I suppose I could add a 1N4007 to
> the order.
> 73,
> Cam Hedrick
> WA4JKW

1N5008 is a 3.3 volt zener diode. Makes lousy rectifier for 110 volts.

With about 120 volts AC applied, the half wave rectifier needs a PIV
twice the peak voltage which is 120 * 1.414 = 170 x 2 = 340. 250 volts
PIV won't hack the service.

The original selenium rectifier was rated at 20 ma. General purpose
silicon rectifier diodes are rarely rated at less than the amp of the
1N4007 family. When you can buy a 1N4007 for a nickle, why ask for a
substitute? Mouser catalog number 833-1N4007. 1 amp 1 KV PIV. 3 cents in
lots of 100 or up, 2 cents in lots of 500... Same price for the 400 volt
PIV 1N4004.

For capacitors, let me put in a bid for Vishay/Sprague TVA Atoms. They
are physically larger than the imports and more like the originals and I
think they will last much longer than any miniature electrolytics. 10
mfd at 150 volts looks like Mouser catalog number 75-TVA1406 for the
magnificent price of $1.15 each.

For the terminal strip look at the Kobiconn with Mouser catalog number
158-1003 at 33 cents.

A good hardware store should have 6-32 x 1/2" stainless steel phillips
head with nut and internal tooth shakeproof lock washer. That will come
close to matching the Collins hardware.

All 516F-2 that haven't had the selenium rectifier replaced NEED it
replaced with these parts. Before it smokes the operator or damages the
radio from drifting bias.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer