Thanks
I can easily apply around 1KV to the big tube's plate by jumper from the
driver amp's plate power supply. Would that protect it OK?
Jerry W4UK
At 10:57 AM 11/16/2001 -0800, 2 wrote:
> >
> >Should I worry about damaging the output tube?
> >
>/ If the screen supply is not fused or current limited, applying screen
>V without anode V is not good.
>
> >I need to power up this old 5CX3000A pentode amp in a limited way to
> >proceed with my checkout. I am nowhere near to applying HV and drive yet,
> >but think I have the bias and SG supplies operational and need to check out
> >a few voltages and circuits. There is a ton of supporting/protective
> >circuitry that I want to observe and try to understand (no schematics).
> >
> >I am concerned about powering up the main tube because I read warnings
> >about operating without plate HV, but perhaps this doesn't apply as long as
> >there is no drive.
> >
>Drive makes no difference. If the anode is mucho positive it is not
>sucking up electrons, the electron go for the screen and screen current
>is astronomical.
>
> >As far as damage to the big tube is concerned, should I be worried about
> >damage to it if I power up all but the drive and HV? I KNOW I have bias on
> >grid 1. I am not sure the screen grid actually has voltage until I smoke
> >test, because it looks like that circuit is awaiting some relays to pull in
> >that probably will in this next step. Any tips/advice/whatever?
> >
>Screen V and anode V should be there when the grid is biased off.
>There's some info and photos of AB1 amps on my Web site.
>
> >cheers,
>Jerry
> >
> >--
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