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[AMPS] amplifier "audio"

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Subject: [AMPS] amplifier "audio"
From: W8IK@IBM.NET (Joe Subich, W8IK)
Date: Mon, 09 Jun 1997 21:36:20 -0400
At 05:14 PM 6/9/97 -0700, you wrote:
>Yes, RF amplifiers can and do modify the audio responce of a signal, both 
>"good and bad".  A few of the AM broadcast transmitters I've dealth 
>with have sections in their manuals regarding amplifier operation for 
>certain "types of fidelity". This also includes interfacing to various 
>antennas which also modify the audio.

Modification of audio response by AM transmitters has absolutely no bearing 
to amateur radio.  In the case of AM radio, the desired audio bandwidth is 
+/- 10 KHz at (approximately) 1 MHz.  In an AM broadcast station one must 
have a *SYSTEM* bandwidth (amplifier and antenna) of 2 % ... the equivalent 
of an antenna and amplifier that would allow one to QSY from one end of 20 
Meters to the other without any change in power output or antenna SWR! 

In AM one needs to stragger tune the entire SYSTEM in order to get the 
required bandwidth.  The music vs. talk tuning is an acknowlegement that 
one need not be quite as "broadbanded" for a talk radio format.  

A properly designed amateur amplifier will have an output bandwidth of 
at least 10 times the 3 KHz bandwidth of the normall SSB signal.  Unless 
the amplifier deisgn is such that it generates in-band distortion products 
(IMD, clipping, etc.), it should have *NO* effect on transmitted audio 
quality.  If it effects transmitted audtio quality, it will only degrade 



    ... Joe Subich, W8IK  ex-AD8I

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