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


Jim Wilhite w5jo at brightok.net
Mon Feb 20 19:32:26 EST 2006


Interesting thought isn't it Don?   97.303 simply states that

(a) An amateur station must use the minimum transmitter power necessary to 
carry out the desired communications.

(b) No station may transmit with a transmitter power exceeding 1.5 kW PEP.



So my question is, when the FCC rolls into my yard to check my power output, 
how are they going to proceed?

If this is the answer, then your conversations are correct, and/or they 
aren't ever going to check!

Interesting question isn't it?  So am I supposed to rely on those expensive 
PEP meters that are sold to the amateur population, or simply put an RF 
ammeter in the output line and do the calculations?  Seems to me the RF 
ammeter might be the best investment, and much less expensive.  But that 
would require us to know a little Algebra, would it?

73  Jim

W5JO

----- Original Message ----- 
From: "Donald Chester" <k4kyv at hotmail.com>
To: <amradio at mailman.qth.net>
Sent: Monday, February 20, 2006 5:51 PM
Subject: Re: [AMRadio] AM Transmitter Advice?? (meter time constant)


>
>>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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