Randy
>Thanks for the suggestions to date.
>
>I have made a little more progress
>
>Using a good light source, the existing caps look fairly bad. The one with
>the lead cut loose measures a dead short on the VOM, and two others look
>like
>they are slightly deformed at the top end with swelling inside.
they are history/RIP
>Cant see the
>diodes and resistors yet, but dont intend to take the boards out until I get
>the new parts.
>
>The good news is that the old Drake undersized (2 watt) glitch resistor
>didnt
>blow, which I am reading as a sign that the immediate problem was upstream
>in the power supply, and not on the amp rf deck (scraping load cap not
>withstanding).
agreed
Undersized is right. A 2w resistor does not limit peak fault current at
3kV. Some 10w resistors will.
> I never did hear any "noise" from the rf deck, and the
>initial power up reading on the plate meter shows that one leg of the
>voltage
>doubler was not operating to begin with.
>
as a one legged FWD should do.
>Looks like I can get some 105 degree computer grade caps from Mouser for
>about $9 each if I buy more than 10, and they are about 1/4 the size of the
>old ones.
I would buy 16 so that I had a complete extra set.
>
>I wonder if I should replace the two giant 50k 50 watt dropping resistors
yes
>which have the unusual mounting scheme at the top of the supply. They
>measure
>ok, about 10% low, but there was at least one thread on this board that i
>found which indicated that they sometimes give an arcing problem from the
>mountings. Seems like drake could have simply put another winding on the
>transformer instead of using these things to get 120 volts from 2500.
>
I would remove R-9, 10, and 11. A 10k - 100k, 0.5w resistor across the
NO cathode relay contacts will cut the tubes off.
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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