[Amps] AL-1200 Low High Voltage (HV)

[John]

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Greetings to the list,

I could use some SME input on the above topic. First some history; I
purchased the amp from someone who was driving it with up to 200watts
input. I was told the amp was modified to allow for this so that it
would not be over driven. That someone is long gone and I have no idea
what modifications were done.

Current: I measured input across both line fuses and its a healthy
250vac. Measuring each input winding pair on the primary side of the
transformer
	Pair 1 Terminal 1 (Yellow [Black/Wht lead]) and Terminal 3(Clear [Black
Lead]) is 124.6vac
	Pair 2 Terminal 4 (Red [Brown/Wht lead] and F1 [Brown lead]I get 124.7vac.

With the above configuration I show 3000v on HV


All wiring on Relays 2 & 3 are in accordance to the Tech Manual

I also reconfigured using the Green lead:
	Pair 1 Terminal 1 (Yellow [Black/Wht lead]) and Terminal 3(Clear [Black
Lead]) is 136vac
	Pair 2 Terminal 4 (Red [Green lead] and F1 [Brown lead]I get 113.2vac.

With the this configuration I show 3300v on HV.

I have replaced all the filter caps (with 470uF 450V 105 degree Nippon
Chemi-con) and checked all the bleeder resistors (all about 49k ohms).
The rectifier board looks clean and no visual damage. Driving the amp
with 100watts I get a clean 1000kw output (using the 3300v
configuration) in which I validated the front panel meter with an
external VSWR meter. Sideband peaks around 1100~1200kw out.

The amp loads up and runs great. I have had good sig reports as is.

So the question now is what else can affect the HV? Something around the
plate end of the tube? or RF Choke?

Thank you in advance, JohnF
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