[Amps] transformers

[Gary Schafer]

Don't forget that Bird specs their accuracy at +- 5% of FULL scale. So with
a 2500 watt slug that is a +- 125 watt error at anywhere on the scale.

Also are you reading the power with a dummy load or into the antenna? If
there is any reflected power the forward reading on the meter will be
greater.

73
Gary  K4FMX


> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Mike Schatzberg
> Sent: Sunday, July 16, 2006 9:10 PM
> To: Tom W8JI; Roy Koeppe; Amps Reflector
> Subject: Re: [Amps] transformers
> 
> 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
> >
> >
> 
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