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[Amps] SR-410A

To: amps@contesting.com
Subject: [Amps] SR-410A
From: Charles Bibb <zedkay@telepak.net>
Date: Sun, 23 Jan 2011 14:34:23 -0600
List-post: <amps@contesting.com">mailto:amps@contesting.com>
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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