On Jun 21, 2006, at 7:07 PM, Randy Moore wrote:
Just completed my KAT1 for my K1 that I finished last night. All the
tests
seem to work properly, and I get a r1.0 (SWR of 1.0) on all 4 bands
(7, 10,
14, & 21 MHz) when transmitting into a dummy load. However, when
transmitting into my attic dipole the KAT1 can only achieve a match on
14
and 21 MHz (1.3 and 1.2 respectively). On 7 MHz I get r4.1 as best
match,
and on 10 MHz I get r3.2, both after much rattling of relays. My K2
(which
I realize has a greater matching range) has no trouble with the same
antenna
setup.
Randy,
It's true that the KAT1 has a smaller reactance range than the K2. This
was unavoidable given the limited PCB real estate.
Assuming all the L and C components are installed correctly, there are
several things you can do to effectively increase the matching range.
Here are the things I'd try.
1. Use a 1:1/4:1 balun with a switch (like the BL2). There are times
when this will transform the impedance to advantage on one or more
bands.
2. Short the twinlead wires together, and connect the two wires
directly to the KAT1's hot lead. Make sure the K1's chassis is grounded
at the antenna jack or elsewhere. This turns the system into a random
wire or sorts, and again this may allow easy matching on some bands.
3. Adjust the length of the twinlead or of the dipole itself by a few
feet at a time. Apparently on 40 and 30 m the reactance is a lot higher
than expected, and by adjusting the length a bit, you can sometimes
move away from very high- or low-impedance points.
Also note that the K1 is reasonably well protected against high SWR.
You can safely use it into high SWR, although you might be down a dB or
two at 4:1 depending on how the transmitter feels about the situation
:)
Let me know if any of these suggestions help.
73,
Wayne
N6KR
---
http://www.elecraft.com
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