R.Measures wrote:
On Aug 30, 2004, at 3:16 AM, Pete Smith wrote:
One of the things I really like about the SB-220 is
that its pi network has sufficient matching range on the low bands so
that, for example, I can run my 40M yagi, which is cut for the CW end,
up well into the phone band, or run my 80m K3LR array, which is cut
for 80CW, up to at least 3900 kHz.
Does the AL-1500 have similar matching range, or will I find myself
more restricted?
I would be careful about using the pi-network of an AL-1500 as an
antenna tuner. It is designed to operate at a particular Q when
transforming the plate impedance of the tube to 50 ohms. Although it
may have sufficient range to match other impedances and cancel out a
certain amount of reactance, under these conditions the operating Q will
be higher or lower than the design value.
If the Q is too low, harmonic suppression will be reduced. If too high,
the circulating current in the tank circuit will be increased. The
coils and bandswitch in the AL-1500 are, er, not over-engineered (!) and
might be damaged under these conditions.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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