[Elecraft] attenuator in amp was Re: K3 and Expert 1K-FA
Tom W8JI
w8ji at w8ji.com
Wed Apr 21 17:50:34 EDT 2010
<< I can not understand why one would want to run the K3
at 100 W rather
than 20/30/50 Watts. Why drive the K3 harder when driving
it more lightly
should improve reliability and possibly improve linearity.
The waste of
energy is also undesirable; the fifty watts out that is
discarded probably
costs 100 Watts of energy. The idea of adding an attenuator
for 50 Watts of
energy sounds mad to me and environmentally unfriendly as
well.>>
Doug,
The primary reason is safety, and the secondary reason is a
cleaner signal.
While the K3 does not have overshoot, many rigs do. This
compounds the drive problem, and it compounds the overshoot
problem.
For example my IC706 overshoots to about 140 watts whether
the output power is set at 50 watts or at 100 watts. If I
have an amp that drives at 40 watts and the radio overshoots
to 140, that is disaster. If I have an amp that drives at 80
watts and the rig overshoots to 140, it might not blow up
and the broadband "pulse" generated by leading edge
overdrive will be a whole lot less level and even less
duration.
The 3 dB attenuator is a **very** good idea, because nothing
can fix or reduce these problems except a pad. External ALC
won't work.
73 Tom
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