[AMRadio] Power Levels

[Wt8r at aol.com]

Here you go Jeff, as requested:

Answered on the list.

Jeff wrote:
<Would you answer a question for me, please?>
<Why did you create your reply to me, off-list, and in a Word document file?>

I did it (Word document/off list) because there are too many points to cover 
in a logical and succinct manner. 
 
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(W5OMR) <snip>
Much the same way that a 100w rice-box needs to be lowered to somewhere 
around
25 watts of carrier, to allow for full audio output.
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--------------------------------------
(WT8R)
This again is in error....perhaps an old wives tale or cod swallop.  The 
reason that the rice boxes need to be lowered to 25 watts is that the final 
transistors are not
specified (selected) for continuous AM operation because, in the SSB mode, 
the
duty cycle is quite low whereas in AM it is 100%.
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(W5OMR)
No sir. The transistorized finals in your Yaewoodcom will allow you to output
100w.
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--------------------------------------
(WT8R)  This is wrong…..you cannot run 100W AM out of  modern (100W nominal) 
transceiver nor can you run 100W RTTY.
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(W5OMR)
There are three components of an AM signal; Carrier, Upper Sideband and Lower
Sideband.
AT THE MOST, you can run 33.3 watts of carrier, because you'll need 33.3 
watts
of Upper Sideband energy
as well as 33.3 watts of Lower sideband energy to complete the AM signal.
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(WT8R) Quoting from the W6SAI Handbook Vol.  22, page 15.3:
"While the average RF voltage of the modulated wave over a modulation cycle 
is the same as for the unmodulated carrier, the average  power increases with 
modulation.  If the radio frequency power is integrated over the audio cycle, 
it will be found with 100 percent sine wave  modulation  the average RF power 
has increased 50 %.   This additional power is represented by the sidebands, 
because as previously mentioned, the carrier power does not vary under 
modulation.  Thus when a 100 watt carrier is 100% modulated by a sine wave, 
the RF power is 150 Watts-100 watts in the carrier and 25 watts in each of 
the two sidebands."
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--------------------------------------
(W5OMR)
25w of carrier, and 25w of sideband power in each sideband - upper and lower,
with a little for overhead.
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(WT8R
I believe this to be in error. There is only 12.5  watts TOTAL of audio in 
both sidebands if the carrier is only 25W.
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---------------------------------------
 (WT8R)
I ask again, if you tune your amp up for 1500W output PEP, and then, without
changing anything, switch to CW and key it, what does the wattmeter read?

 73 de
 Dave in Dayton, WT8R



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