I test into my dummy load with a 50 resistor and 1 gallon of oil, which
reads 1:1 SWR, or operate my 20 meter monoband yagi at such a frequency
where SWR is also 1:1. The results are the same.
73 and Happy DXing,
Mike
W2AJI
----- Original Message -----
From: "Gary Schafer" <garyschafer@comcast.net>
To: "'Amps Reflector'" <amps@contesting.com>
Sent: Sunday, July 16, 2006 10:31 PM
Subject: Re: [Amps] transformers
>
> 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@contesting.com [mailto:amps-bounces@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@w8ji.com>
> > To: "Mike Schatzberg" <cherokeehillfarm@earthlink.net>; "Roy Koeppe"
> > <royanjoy@ncn.net>; "Amps Reflector" <amps@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
> > >
> > >
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
>
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