[AMPS] Linear AMP timing

[Bill Turner]

On Wed, 08 Aug 2001 14:37:01 -0400, Pete Smith wrote:

>Well, I don't know, but when the T/R relay on my SB-220 began to stick in
>the "on" position, it turned out to be the bias contacts that were the
>worst burnt.  Maybe a sign that they were trying to open too soon?  

_________________________________________________________

The contacts must be opening more than just bias, most likely the actual
cathode current.  Since this is DC, you should be able to suppress the
arc by placing a cap and resistor in series across the contacts.  The
best value has to be determined empirically.  I'd try a .1 uf in series
with 100 ohms and then tweak the values for minimum visible spark at the
relay contacts.  You should be able to get the spark down to barely
visible.

This will delay the turn-off time of the tube by a small amount; perhaps
a few milliseconds.  Keep this in mind in relation to the timing of the
other relays.

Bill, W7TI

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