[Amps] transformers

[Mike Schatzberg]

Well, I stated what I have used for measurement, and I realize that the Bird
and Nye Viking are not a Hewlett Packard.  I can accept that both meters may
be off by 10%, even though their accuracy is supposed to be about half of
that.  Even my Autek says the same thing as the two others, interesting that
they are all exactly in error by the same amount.  They all agree with the
wattmeter in my Mark V also.

It's good to finally learn that I have been operating well below the
permitted maximums all these years.

I don't think I'll start loading the amps any higher however.

73 and Happy DXing,

Mike
W2AJI
----- Original Message ----- 
From: "Tom W8JI" <w8ji at w8ji.com>
To: "Mike Schatzberg" <cherokeehillfarm at earthlink.net>; "Roy Koeppe"
<royanjoy at ncn.net>; "Amps Reflector" <amps at contesting.com>
Sent: Sunday, July 16, 2006 9:43 PM
Subject: Re: [Amps] transformers


> > My SB 200 produces 700 Watts PEP, with about 50 Watts PEP
> > drive, and my SB
> > 220 produces about 1.5 KW PEP (both amps on 20 meters)
> > with about 80 Watts
> > PEP drive.
>
> I've never seen a pair of 3-500Z's driven with 100 watts
> produce 1500W PEP ***on an accurate power meter*** with only
> 3000V on the anode.
>
> Neither did B&W. Neither did Viewstar. That's why they ran
> 3500V plus on the anodes. Every manufacturer has fought this
> gain problem.
> It takes about 3400 volts or more to get 1500W out with 100W
> drive.
>
> This isn't to say a pair of 3-500Z at 3000V won't show 1500W
> PEP on some wattmeters. I've just never seen that power on
> accurate meters.
>
> All of my SB220's, even with the grids grounded, only make
> around 1200-1300 with100W drive on a known accuracy meter.
>
> By the way, a typical o-scope is one of the least reliable
> common ways to read power. First, scopes have passband
> ripple. They are designed of good response to a stepped
> waveform, frequency response flatness (or lack of ripple) is
> secondary. Second, they are susceptible to common mode on
> probe leads. Third, they don't store the absolute peaks
> unless you have a storage scope and are lucky enough to
> catch the peak. Fourth, any error they do have is compounded
> by the fact power is a square of the measured voltage, so
> the error is squared. Fifth, they are load resistance
> critical.
>
> RF power meters with peak storage circuits are the best way
> by far.
>
> 73 Tom
>
>