On Fri, 4 Mar 2005 13:41:50 -0600, "Richard Fry"
wrote:

If the PAs alone were as (in)efficient as you imply with your calculations,
power consumption for the entire transmitter would be considerably higher.

The implication is drawn by and from your inertia.

Common sense should tell you that PA module efficiency would have to be much
higher than the efficiency calculations you posted in order for total power
consumption to be as stated on the Harris spec sheets.

Hi OM,

It is tedious to have to carry your water for you. I had to chase
down your Mendenhall references, this seems to be a consistent trait.
Claims are generous in this group and heavily discounted due to the
paucity of facts. Such facts as may be drawn out, but could have had
been as easily offered by you:

"For even greater reliability, any
PA module can be used as an IPA module,
with absolutely no modification."

It is quite obvious that as an IPA, that in the lower wattage systems
it represents overkill at 845W to generate drive to final PAs to 2.2
KW output. Hence the lower total efficiency.

On the other hand, an IPA driving 845W to generate 22KW obviously
makes better efficiency sense and is found in the overall 64.5%
figure.

NOW, if the PA finals, accounting for 22KW are 80% efficient, that
must mean that they only consume 27.5KW of power to do so, and that
with a power input rating of 31KW then leaves the IPA (an identical
80% efficiency module) and control circuitry to absorb 3.5KW to
deliver the drive of .845KW.

It follows that for an 80% efficient IPA, it accounts for 1KW power
consumption. This remainder is easily attributable to power supply
losses (if we simply assign an industrial average efficiency of 95%
for power conversion) otherwise the system TTL circuits and LCD meters
suck down 2.5KW on their own.

This, as you put it (but fail to evidence), would quickly subdue
suspicion. And an equal treatment to more conventional, retail
Amateur Radio Transmitters also reveals efficiencies through the same
exercise. It is quite evident that such transmitters are no where
near these vaunted examples - but few dare venture into these
dissections.

73's
Richard Clark, KB7QHC