[AMRadio] AM Transmitter Advice?? (meter time constant)


Donald Chester k4kyv at hotmail.com
Mon Feb 20 18:51:37 EST 2006


>From: "Jim Wilhite" <w5jo at brightok.net>

>
>This started me wondering about measuring PEP and Carrier Power today.  So 
>I went to the FCC website to look for the standards that apply. Well I 
>finally found it.  Here is a link to Chapter 1-FCC, Subpart J, Section 
>2.1046, if anyone is interested in reading it.  I hope the link works.
>
>http://a257.g.akamaitech.net/7/257/2422/09nov20051500/edocket.access.gpo.gov/cfr_2005/octqtr/47cfr2.1046.htm
>
>This was originally 39 FR 5919, 2/15/74    Redesign and amended at 63 FR 
>36599, 7/7/98
>
>Good reading if one wishes to be compliant.


Brings up a couple of interesting points:

(1) Looks like they state two separate power standards:  carrier power for 
steady output emissions like FM, AM, CW, etc., and p.e.p. for modes with 
fluctuating output, like SSB, ISB and controlled carrier.  If the AMATEUR 
regulations had been written that way, there would have been no AM power 
reduction.  The power output rules ARE written in that fashion in Canada.

(2) "...The electrical characteristics of the radio frequency load attached 
to the output terminals when this test is made shall be stated."

Fat chance that more than about 1% of amateur installations could meet that 
criteria.  It requires working into a known, nonreactive, purely resistive 
load.  How many ham antennas present a perfectly flat swr and  50-ohm 
nonreactive load at the transmitter end of the feedline?  This measurement 
would require a calibrated rf impedance bridge, and knowledge of how to use 
it.  How many appliance operators of today would qualify?

Don K4KYV



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