[Elecraft] Re: KAT1

[wayne burdick]

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

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