QROKING@aol.com wrote:
> For example, if I use a bird 43 wattmeter and I load my amp and measure 1500
> watts with it, Am I running more than the legal limit or right on it?
The Bird reads average power, for a carrier free of amplitude
change..average is equal to peak.
> If I
> dont have a meter that will read PEP how do I know if I am complying with the
> power rule?
On SSB, AM, or other amplitude varying modes, you won't have any idea.
> If I run 1500 watts on CW (output) is that legal? A CW carrier
> is average power not PEP , so in this case, running CW is the peak and
> average power equal?
Yes.
> Now without reloading my amp from the 1500 watt output
> in CW and I now switch to SSB, what will my PEP output now be?
Slightly more than 1500 watts in the normal case. The reason for this is
primarily due to less than perfect voltage regulation in the equipment.
> Would it be
> 3000 watts pep?
Certainly not, unless the power supplies you use were lousy under steady
load.
> If so I will be illegal right. I would then have to detune
> the amp to be within the 1500 watt output mark. YES? NO?
No. The last thing you want to EVER do is reduce power by tuning the
amp. Amps should be loaded for maximum power, and DRIVE power reduced.
Underloading the amp causes bandswitch failures, tank arcing, excessive
grid current, splatter, and other maladies.
> So why did they
> change the rule on how power is measured?
Because who cares how much input power someone runs? The only thing
important is how much output power they have.
> Another issue, Some so called wattmeters that some companies sell, Now
> are they REALLY wattmeters or are they only calibrated power indicators?
> And if so, dont you agree, that unless your SWR is at 1:1 when you read that
> type of meter, the reading will be true then and only then, as opposed to
> reading it at an SWR of 2:1? When it comes to measureing power output, I
> will only believe a bird 43 into a dummy load, anything else would be suspect
> to me!
If you have a directional coupler meter, like the Bird, all you need do
is subtract the reflected power from the forward power to get source
power. Most meters are power meters, they samle voltage and current. The
phase difference between the voltage and current "tells" the meter
whether it is forward or reflected power.
If you have 2500 watts forward, and 1000 watts reflected, it is 1500
watts output.
73 Tom
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