[Elecraft] [OT] High SWR on 20 and 40

[Guy Olinger K2AV]

The 16 feet of window line makes me wonder if you're not trying to do
a half-size G5RV, but got the top dimensions wrong.  It would be 51'
(instead of 67 which is REALLY bad on 20 meters), or a little longer,
say 54' if you wanted to load on 17m and 12m.

My K2/10 and the auto tuner will match most anything, but your lengths
are not anything I would do on purpose for multiband  : >)

On Fri, Jan 15, 2010 at 7:49 PM, Don Wilhelm <w3fpr at embarqmail.com> wrote:
> Dave,
>
> If you did not disconnect the KAT2, then please tell us the setup (all
> the connections) when you have SWR readings below 1.5.
> That may be capable of providing some sort of clue.
>
> 73,
> Don W3FPR
>
> djmd wrote:
>>
>> And re: your follow up - all the testing was done with the KAT2. I have
>> never disconnected it.
>>
>>
>>
>>
>>
>> Don Wilhelm-4 wrote:
>>
>>> Dave,
>>>
>>> Is that a 1:1 balun or a 4:1 balun.  Usually a 1:1 works better, but
>>> whichever balun you are using, try the other one and see what happens.
>>> Do you have an antenna analyzer?  or can you borrow one?  If so, what is
>>> the impedance at the end of the coax?  Both the resistive and reactive
>>> components please - just the SWR does not provide much information on
>>> how to advise you to proceed.
>>>
>>> You may be better off eliminating the coax entirely and running the
>>> window line all the way into the shack.
>>> 73,
>>> Don W3FPR
>>>
>>> djmd wrote:
>>>
>>>> Hello,
>>>>
>>>> I have been trying to troubleshoot my antenna system, and have been
>>>> trying
>>>> to avoid the dreaded "high swr" post, but I've run out of ideas, so I'm
>>>> turning here.
>>>>
>>>> First let me explain my system. 67' dipole fed by 16' of window line.
>>>> That's
>>>> connected to an Elecraft balun. From the balun, there's a short piece of
>>>> coax going to a barrel and into the basement (through a piece of cement
>>>> backerboard. From inside the basement, there is another piece of coax,
>>>> about
>>>> 12', connected to the barrel, and going up into the bedroom directly to a
>>>> K2
>>>> with an autotuner.
>>>>
>>>> Before the K2, I was using a Yaesu FT840 with an MFJ tuner. After
>>>> tweaking
>>>> the window line length and the actual length of the dipole, I never
>>>> really
>>>> had a problem with SWR (well, according to what the MFJ was saying, which
>>>> may or may not be totally accurate.) Usually 1.5:1 or under on all bands.
>>>>
>>>> With the K2/KAT2 in place, the SWR reported by the tuner is all over the
>>>> place. The only one that gets less than 1.5:1 is 30m. Most bands are
>>>> pretty
>>>> random, anywhere from 3:1 to 7:1. However, on 20 and 40, it generally
>>>> does
>>>> not get below 9.9:1.
>>>>
>>>> I've tried 4 different lengths of coax between the barrel (inside) and
>>>> the
>>>> rig... 3', 6', 12' 20'. I've tried a couple different lengths between the
>>>> balun and the barrel on the outside.
>>>>
>>>> When I attach the balun directly to the K2 I get <1.3:1 on all bands
>>>> (most
>>>> are 1:1.) With a short piece of coax between the rig and the balun, I get
>>>> the same results. I've also attached my dummy load to the barrel on the
>>>> outside of the house, and tested it from the shack, and I saw 1:1 no
>>>> problem.
>>>>
>>>> I totally understand the concept that if "A" works and "B" works, "A+B"
>>>> doesn't necessarily work. I understand it's a whole system. But I've
>>>> tried
>>>> so many different combinations of coax on each side, and don't understand
>>>> why my SWR is basically infinity:1 on 20 and 40, when they seemed to
>>>> match
>>>> reasonably with the old system. I have not tried different lengths of
>>>> window
>>>> line between the dipole due to the fact that I had it perfectly trimmed
>>>> for
>>>> my old system. But I have plenty of it and would be open to trying
>>>> anything.
>>>>
>>>> Just trying to get the most I can out of my modest 10W. :) Any
>>>> suggestions
>>>> would be appreciated!
>>>>
>>>> 73,
>>>>
>>>> Dave
>>>> K8DJW
>>>>
>>>>
>>>>
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