[TenTec] Correction: Power input: 580 Delta transceiver

Mon, 13 May 2002 02:41:41 +0100

For the longest time the FCC measured transmitter power for regulatory
purposes in the US Amateur Radio Service by DC input power.   I know this
was still true when I was first licensed in 1975, and I believe continued
for at least several years after that.   As you know tube-type
transmitters had a plate current meter, and voltage could be measured
with a VOM or VTVM (or assumed to be a certain specified value,)  hence,
DC input power could be easily determined.  For instance, the power limit
for Novice class operators was 75 watts DC input, and other limits
applied in certain bands and so forth.  (I can't remember the maximum but
I think for SSB it was 2000 watts PEP DC input).   To measure RF output,
on the other hand, as I believe some old texts explained, required
expensive test equipment not commonly in the average ham shack and
especially unlikely for the home-brew station.   Eventually, of course,
the FCC went to regulation by RF power output for Amateurs.   Probably
the advent of broadbanded solid state transmitters, availability of
reasonably priced and accurate wattmeters, etc. made the switch
practical.   Even the power limit in the Novice bands was set to 250
watts output, so just about any rig would fall well below this level
without necessitating any exact measurement.  However, I'm sure many
Amateurs, even in the late 80s,  were still accustomed to power expressed
in terms of DC input, so that is why the practice continued in some
advertising.   Many would have been replacing tube-final equipment rated
in DC input power, and thus could make like comparisons on the newer
equipment.   

73 de Mark N8COO

On Sun, 12 May 2002 16:02:46 -0400 Don Jones <[email protected]> writes:
> It may be strange, but rating ham transceivers in terms of input 
> power continued
> throughout much of the 80s decade. The back cover of my 1988 Radio 
> Amateur
> Callbook is an advertisement for the Kenwood TS440S which states "RF 
> input power
> is rated at 200 W PEP on SSB, 200 W DC on CW ......" No where in the
> advertisement is the power expressed in terms of output.
> 
> In the same callbook, Yaesu used output power in their FT-757\GX/II
> advertisement. I guess things were starting to change by then.
> 
> 73 - Don Jones N4TN
> 
> 
> 
> Adam Farson wrote:
> 
> > Strange that any manufacturer should specify DC input, rather than 
> RF
> > output, as late as the 80's....
> >
> > When I was working professionally as an RF designer in the 1960's 
> in the
> > military and commercial radio comms field, our radio regulatory 
> agency
> > specified RF output for type-approval purposes. We had Bird 43 
> power meters
> > traceable to our national standards bureau. Even in the Amateur 
> Service, the
> > SSB power limit back then was stated as 400W PEP output (as 
> opposed to 100W
> > DC input to the RF PA for all other modes).
> >
> > Best 73,
> > Adam, VA7OJ/AB4OJ
> > North Vancouver, BC, Canada
> > http://www.qsl.net/ab4oj/
> > Note new e-mail address:
> > mailto:[email protected]
> >
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]]On Behalf Of Sam Timberlake 
> KF4TXQ
> > Sent: Sunday, May 12, 2002 11:38
> > To: [email protected]
> > Subject: [TenTec] Correction: Power input: 580 Delta tranceiver
> >
> > I appreciate Mike's observation re: 200W DC input on the Delta.
> > Mike is indeed correct. My apology to the list.
> >
> > tnx es 73,  Sam KF4TXQ
> >
> > _______________________________________________
> > Tentec mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/tentec
> 
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