[Boatanchors] Re: selenium rectifier... replacement strategies

[Rolynn Prechtl K7DFW]

>"but someone said the voltage drop of s silicon diode is constant at 0.7
volt.  This is quite incorrect, and I wish the ARRL would quit propagating
this myth in some of their publications and articles"<

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No it's not constant, but what's the ARRL have to do with a universally
accepted junction voltage?

My experience and training has come from the USAF, IBM and Tektronix, Inc.
They all use 600 to 700 mV for the expected junction voltage of a silicon
device (with reasonable currents).

This ball park figure plays in actual use. It works at the current levels
most of us see and use. It works when troubleshooting and repairing.

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If the ARRL is wrong, then semiconductor manufacturers have followed.

 http://www.americanmicrosemi.com/faq.htm#3

"Vf is the forward voltage drop of a semiconductor. It consists of two
components; an intrinsic offset voltage (0.3 volt for germanium ; 0 .7 for
silicon) plus If x R, where R is the resistance of the semiconductor and
leads multiplied by the current, If. Vf is undesireable and is minimized
whenever possible as it adversely affects the efficiency of the circuit and
results in a power loss, that loss is Vf xIf".
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There are children listening so why confuse them.

Remember, "it's for the children".


RP

..._._