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

Donald Chester k4kyv at hotmail.com
Mon Feb 20 12:00:41 EST 2006

>From: "Bob Bruhns" <bbruhns at erols.com>
> > Bacon, not trying to be contrite, but where in the
> >old rules did the .25
> > second time constant appear?  I have a copy of the
> >old rules and don't see
> > it.  It says only that "have the means".

>Hi Jim... Hmm, it came from my sometimes flakey
>memory...  I'm pretty sure there was a 0.25 second spec
>for the metering somewhere... maybe it was simply
>assumed that the meter time constant would be about
>0.25 seconds.

>From ARRL's "Single Sideband for the Radio Amateur," p. 14, 1958 edition:

                            S.S.B. POWER LIMIT

...We quote from a Commission letter addressed to ARRL:

   The following . . . may be considered as a presently acceptable method 
for determining the d.c. plate power input to the final r.f. stage of a 
single-sideband amateur transmitter:
   The maximum d.c. plate power input to the radio frequency tube or tubes 
supplying power to the antenna system of a single-sideband 
suppressed-carrier transmitter, as indicated by the usual plate voltmeter 
and plate milliammeter, shall be considered as the "input power" insofar as 
Sections 12.131 and 12.136(d) of the Commission's rules are concerned, 
provided the plate meters utilized have a time constant not in excess of 
approximately 0.25 second, and the linearity of the transmitter has been 
adjusted to prevent the generation of excessive sidebands.  The "input 
power" shall not exceed one kilowatt on peaks as indicated by the plate 
meter readings.

Don k4kyv

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