[Elecraft] KAT500 remote operation

[n5ge at n5ge.com]

Knut,

I did what Don suggests to match my MARS NVIS Loop which is fed with
450 ohm ladder-line and has a ten foot 450 ohm ladder-line stub
diagonally opposite the fed corner, but added 75 ohm coax rather than
50 ohm.

I made three lengths of RG11, 6.5 feet, 6 feet and 9 feet.  With
those three lengths you can try 6.5 feet, 12.5 feet, 15.5 feet and
21.5 feet to test with.  After testing I ended up with 15.5 feet
which I coiled up between the 4:1 balun and the 50 ohm coax feeding
the KAT500 and KPA500.  I used an AIM 4170 analyzer and looked at SWR
and Rs readings.

When you do that you compare the SWR and Rs value at a given
frequency and if the SWR is > Rs you divide SWR by Rs looking for a
value of < 10  If the value is < 10 the KAT500 can tune it at high
power.  On the other hand if the Rs is > SWR you divide the Rs by the
SWR also looking for a value of < 10.

When you have value at each of the frequencies within desired range
of less than 10 The KAT500 will tune them.

My loop has 388 feet of wire in it and will tune with the KAT500 from
3.5 to 10.5MHz, except close to the K3 IF frequency, which can't be
used anyway.

Good luck with your antenna trimming!

73,
Tom
Amateur Radio Operator N5GE
ARRL Lifetime Member
QCWA Lifetime Member    

On Fri, 07 Dec 2012 20:00:24 -0500, Don Wilhelm
<w3fpr at embarqmail.com> wrote:

>Knut,
>
>You might try adding or subtracting feedline at the shack end of the 
>feedline to bring the SWR down on those bands.  I would suggest 
>experimenting with an antenna analyzer rather than the tuner - you will 
>be able to see which way to go for making improvement.
>
>The fact is that the feedline with SWR will act as an impedance 
>transformer, and it will be more of a transformer on bands with high SWR 
>than on the bands that are better matched.
>
>Some experimentation may be in order.
>
>73,
>Don W3FPR
>
>On 12/7/2012 5:52 PM, ab2tc wrote:
>> Hi,
>>
>> Still can't manage to get any improvement doing this. Anyway, right now the
>> tuner is doing a great job to my G5RV on all bands except 15m and 80m. For
>> those bands the raw SWR is above 12:1 so is outside the design parameters
>> for the tuner. These are screen shots for the bands where the tuner is
>> finding a good match:
>>
>> http://ab2tc.getmyip.com/g5rv_10m.png
>> http://ab2tc.getmyip.com/g5rv_12m.png
>> http://ab2tc.getmyip.com/g5rv_17m.png
>> http://ab2tc.getmyip.com/g5rv_20m.png
>> http://ab2tc.getmyip.com/g5rv_40m.png
>>
>> I'll continue to work on the 15m and 80m to see if I can improve it.
>>
>> AB2TC - Knut
>>
>
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