Phil Kane wrote:
On Sun, 18 Jun 2006 21:36:25 -0700, Vic K2VCO wrote:
I'm thinking about duplicating the KPA100 LP filter section so I can use
this amp as an output stage for another rig.
Why not use an outboard LP Filter like most of us have done
for decades? I wouldn't connect ANYTHING to a HF antenna
without one.
Well, you need several selectable filters, because you need to reduce
the low-order harmonics. The usual lowpass TVI filter cuts off around
30 MHz or even 50 MHz. But you need to eliminate the 14 MHz (etc)
harmonic that goes with your 7 MHz desired signal. A tube rig doesn't
have this problem because the tuned plate tank circuit has enough
selectivity to reduce these enough.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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