[AMRadio] Power Levels

[Jeff Edmonson]

: >There is no need to apologize.  Especially for the anal retentive >
: >>individuals.
: >>
: >> LOL ! !  You use terminology you do not understand.
:
: >Maybe better than you are capable of undeerstanding.
:
: You have been called on this, so tell us what YOU think this term means
: and maybe why you chose to use it. Looks to me like a Freudian slip.

What's it got to do with Amateur and/or AM Radio?

in your reply, that should have been left out.  This is not some
sort of pissing match, for crying out loud - this is about Radio.

Let's please stick to the subject at hand, ok?  Leave the flame-thrower
checked at the door, along with the brass knuckles, the tommy guns and
any other symbol of physical violence you choose.

Bottom line, it seems that there are several manuals for the BC-610 out there,
but lets get back to the ORIGINAL posting, which was the efficiency
of a transmitter.

I still maintain that if a triode has 2000VDC applied to the plate (Ep) and is
drawing a plate current (Ip) of 250mA, then the DC Input power is 500W to
the final.

Class C amplifiers are (in all practicality) 75% efficient.
75% of 500 = 375W and, as others have pointed out, circulating current in
the tubes, the final, etc - the actual power output is more like 335w, but
for the sake of argument, and ease of calculation, lets just say that the 375W
figure stands.

I forget the exact mathematics (Don?  Bacon?) to explain how P.E.P is achieved,
but for closeness sake the multiplication is 4.  So, 375w, 100% modulated, is
equal to 1500w P.E.P output.

I think I'm remembering... damn it sucks to be getting old (and I'm only 43 ;->)

Let's say you've got a 375W carrier and look at it on an o'scope.  The scope is
set
so that the carrier will fill two divisions.  Then modulate the carrier at 100%.
The audio peaks, above and below the carrier will be 4 times that of the
carrier.
The carrier is 375 watts, and 375 times 4 = 1500.

Note: This is Peak Envelope Power and not to be confused with Peak Instantaneous
Power, which is a different calculation altogether.

Bottom line, and I think this point has been made before, even *if* you're
running
a kilowatt DC input to the final (750w carrier) and modulate it at 100%, you're
P.E.P.
is 3kw, and that's *only* 3db louder than 1500W P.E.P.  3db!

Remember, an increase in power from 100w to 200w is an increase of 3db, and
isn't
all that impressive.

An increase from 200 to 400W is 3db.  The total increase is 6db, to go from 100
to 400w.

to go from 1000w to 2000w is an increase of 3db - double the power.
A 6db increase from 1000w would be the equivalent to 4000w.

 To the human ear, 3db is just "barely" perceivable.
on an S-meter, one S unit (on the older rigs, assuming 50uv for S-9) is equal to
about 6db.

Running 500w DC input to a final, ignoring efficiency, would seem to me, to be
the "gentlemanly"
power level to operate.  However, if you can figure a way to obtain asymmetrical
audio without
pinching the carrier and causing distortion, say - a ratio of 4:1 instead of 2:1
audio, then your 1500W P.E.P. turns out to be more like 3000w P.E.P. with only
375w of carrier :-)

73 = Best Regards,
-=Jeff/W5OMR=-