On Tue, 2007-10-30 at 11:36 -0500, Rob Atkinson wrote:
<<<Can you measure 20% at the other end of the path? That's all of 0.8 dB
and when propagation changes sometimes more than 10 dB in seconds...
73, Jerry, K0CQ>>>
Hi Jerry,
The next time you fork out your hard earned dollars for a new 200 w.
rig and it only puts out 160 w., I'll expect you to just put up with
it because it's only N dB less than spec'd output; the next time you
shell out $$$ for a new 100 w. rig and it only puts out 80 w.,
Just a couple tenths voltage drop in the 12 volt supply to the PA will
cause that much power drop. Can't always get around it, besides it still
can't be detected at the other end of a path whether local or long
distance because of propagation path variations and the receiver being
logarithmic (as are ears) with the smallest meter divisions be 6 dB (4X
power). Besides running a tube at 80% power ratings tends to seriously
lengthen its lifetime.
or the
next time you get a new car that's supposed to do 80 mph and it
red lines at 64, I'll expect you to just suck it up and accept the
degradation in performance with some engineering rationalization.
That's not in a logarithmic time variable medium, that's a linear time
fixed medium and the difference is very perceivable and measurable.
By
the way, get on the horn and tell the 1A broadcast station that
shelled out $250,000 for a new Harris dx50 that it's okay if it only
puts out 40 kw carrier instead of 50 and listen to what the C.E. has
to say about that.
He would be livid, but if it save him 20% of his power bill and doubled
tube life (and if the FCC would accept the operation) and only cost 1%
of his audience, he'd be turning it back. NBS WWV stations run rigs at
half rated power or less to get extremely long tube life and reliable
operation. The C.E. of WHO is chewing his teeth up with the number of
times a day that the signal goes off the air now. Besides measuring
field strength at a couple miles he CAN detect the reduced power, but
your receiver can't tell the difference at 1 mile or 1000 miles.
73,
rob / k5uj
73, Jerry, K0CQ
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