[AMRadio] AM Amps


Geoff w5omr at w5omr.shacknet.nu
Tue Jan 11 19:49:08 EST 2005


Gary Schafer wrote:
> By "legal power out of the 813's" I assume you mean 375 watts carrier?

Why assume something that is false??

That statement is -designed- to put you on edge, Gary.  Perhaps 
it's just my perception, but it simply appears as if you're not 
paying attention.

NO WHERE does it say that 375w of carrier is the 'legal' limit.

The LEGAL limit is 1500w PEP output.  It's just a point of 
reference, that if you modulate a 375w signal with a sine-wave to 
100% audio, then you will reach 1500w pep output.  The truth of 
the matter is, we don't -speak- in sine-wave.  Our voices are 
rather asymetrical.  Some of us have voices that are rather 
'peaked'.  In order for the audio amplifying equipment to 
properly modulate 375w of carrier, instead of needing to only be 
50% of the carrier, or 187.5w of needed audio, you -might- wind 
up needing an audio system with the capability of producing 
upwards of 600w of AUDIO.

(ref: 
http://w5omr.shacknet.nu/~wa5bxo/asyam/Amplitude%20Modulation.htm)

THIS IS NOT TO SAY that you'll be pushing your positive peaks 
that high, but in order to keep your signal clean, and well 
within "good engineering practice", you certainly don't want any 
flat-topping or distortion.  Anything in the audio system that 
does -not- allow your audio to be clean and free of distortion 
then, by definition, wouldn't be operating within "good 
engineering practice".


73 = Best Regards,
-Geoff/W5OMR




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