Actually, this was a regulatory issue. Until sometime in the 1980's the
FCC specified that the DC Power Input to the Final Amplifier stage was
the Power of record. In other words, the actual output power was never
considered for purposes of testing a station's compliance with the
rules. Thus, in the case of a Novice running CW on HF, 75 Watts was the
maximum amount of input power that could be applied to the Final
Amplifier stage. This would be calculated by simply multiplying the
Final Amplifier's Plate Voltage by the Plate Current under Key Down
conditions. The actual output power would vary, depending on the
efficiency of the final amplifier. This was typically 50 to 65 percent.
Thus, two stations could be running the legal 75 Watt input power, but
their actual output power could vary by more than 10 Watts.
The ones who lost out on this rule change were the AM operators. They
had been allowed to run 1000 Watts DC input power, netting perhaps 500
Watts out. When the Commission change the rules to specify that Power
was to be measured as the Actual Output Power, they set the maximum
Amateur Output Power as 1500 Watts PEP. This meant that the AM operators
had to Reduce their Carrier Power to 250 Watts to comply with the new rule.
73,
Mike
NM7X
*Original Message*
------------------------------
Date: Sun, 2 Sep 2007
From: Kevin Purcell <kevinpurcell@pobox.com>
Subject: Re: [TenTec] power output of ten tec delta
There was a habit some time ago of "power inflation" in marketing by
quoting the DC input power rather than the output power.
This seems to have seeped into various websites documenting the gear
who take the power number without actually checking what it is.
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