On 01/23/2011 03:34 PM, Charles Bibb wrote:
> Hi, All
>
> I need a little help from you guys more familiar with commercial gear
> than I am. Recently I was given (most of) a Scientific Radio Systems
> SR-410A VHF power amp and power supply. The amp uses a single 8877
> tube. I do not have the manual. Does anyone know what plate voltage
> this amp runs on the tube?
>
> I've removed the HV transformer and have run it with only a few volts
> on the primary, instead of 234V, and even with a small load on the
> secondary I get a transformation ratio of 1 to 13.25. Using 234V on
> the primary, this would yield 3100V on the secondary. This voltage
> run through a bridge rectifier and filter would result in nearly
> 4400VDC key up on the plate. Is this correct for this amp? Seems a
> tad high considering that the maximum rated plate voltage on the 8877
> is listed as 4000V.
>
> The transformer is a Basler Electric EB3041*001. The asterisk stands
> for a number that I cannot read because it has been rubbed off. Does
> anyone have a wiring diagram for the primary taps on this particular
> transformer? It appears to be a dual winding primary, with the
> windings connected in series, and with several other tap positions
> allowing for other voltages. If this one was run from 208V, the
> secondary would be approx. 2760V, and after rectification and
> filtering, 3900VDC. That sounds more like it.
>
> Any info?
>
> TIA and 73,
> Charles - K5ZK
>
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Things were designed when the world (our part) was 115/230 volts.
As Carl asked, is it a choke input, what would be .9 x the secondary.
I have a couple transformers marked 220.
If you have taps put it where you want.
A bit more of a concern is the filament adjustable? You want 5.000 or a
little less.
As I type, I'm looking at 242/121 volts coming out of the wall. My
little 30L1 driver wants 115.
It's OK, just think of all those KW hours you are paying for and don't want.
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