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[N9MXY]

My 811H Plate is near 1.8KV no load and it voltage drops about a needle width below 1.5 KV during full output.  I have a 25amp 120VAC dedicated line that measures 123.1VAC with no load and 122.6 Powering the amp, my ICOM 706, Rotor and remote switchbox.  In my mind a 16% drop in plate voltage is excessive...

[WB8PFZ]

Based  on your primary voltages your high voltage should drop 7 volts. Are the meter dropping resistors ok?

[WB8PFZ]

The more I thought about this I would say that is normal voltage drop.

[WB8PFZ]

Do to transformer efficiency and voltage doubler circuit.

[N9MXY]

Yeah, I just went through th 811H manual and it says 1.5KV under load.  The thing that got me onto this was I just ran the dedicated line to the shack a couple weeks ago and I was expecting it to decrease the sag and it didn't

[K1VSK]

It won’t make any noticeable difference in output. It’s normal.

[KD6VXI]

It won’t make any noticeable difference in output. It’s normal.

No, but it will make a difference in IMD.

Which the 811 tube isn't known to be great at anyway.

If you just ran a new circuit, swap it to 220.  The transformer drop will improve if anything due to better efficiency.

--Shane
WP2ASS / ex KD6VXI

[KH6AQ]

With 100W drive on 7 MHz my AL-811 (572B tubes) plate voltage meter shows 1700/1500V.

[KU3X]

........ I have a 25amp 120VAC dedicated line that measures 123.1VAC with no load and 122.6 Powering the amp........

Don't waste any time changing from your 120 volt line to a 220 volt line. You are not drawing that much current that it would make any difference at all.
It sounds like you amp is working as it should.

Barry, KU3X

[W1QJ]

Unless you have a peak reading digital read out wattmeter  like the LP100a (or eq) or a Powermaster, you can’t see or measure the improvement from switching from a stiff 120 line to a stiff 240 line.  Without proper instrumentation you can’t see it.  If you did have it, you’d see it and wouldn’t be questioning tne difference!

[KD6VXI]

What if you have the powermaster, the LP100A AND a Bird RF Analyst digital meter all inline?  Lol.

Yes, I like watching wattmeter all argue with each other.  But the swr shutdown for the LP100A and the Powermaster mean they both see a lot more action than the Bird in my shack.

Matter of fact, I'll probably be selling most of the bird stuff sans my 25kw slug.  Jay stopped making the 20kw coupler so may need that one from time to time.

--Shane
WP2ASS / ex KD6VXI

[KD7TWW]

I would suspect your meter is whacked. Your House current sounds good. In Boise Downtown I get 121.3VAC Winter and 120.5VAC  Summer. You did not say if you used a HV Probe or not? And how many watts? at that drop? 73 

My 811H Plate is near 1.8KV no load and it voltage drops about a needle width below 1.5 KV during full output.  I have a 25amp 120VAC dedicated line that measures 123.1VAC with no load and 122.6 Powering the amp, my ICOM 706, Rotor and remote switchbox.  In my mind a 16% drop in plate voltage is excessive...

[KU3X]

  I have a 25amp 120VAC dedicated line that measures 123.1VAC with no load and 122.6

As mentioned above, "Your house current sounds good."
120 volts times 25 amps = 3000 watts. From what you said, you are drawing less than 1300 watts off of that line. That's less than half of its capacity. Changing to 220 volts won't do a thing for you.
Barry, KU3X