Hi Again Mike
Read through the archives on this subject so I wrote down my thoughts on
this and what I have tried.
Extra feed line you can coil up before point of entry maybe 3 foot
diameter. I had 40 feet of feed line on 80M long ago so I put 2 roller
indutors in series, one on each leg and tuned the antenna that way. You
can do the same with some home made coils wrapped on PVC pipe and tune.
Rule of thumb most coax has has about 25pF capacitance per foot so you can
make caps and prune. Try cheap CATV cable first so if you cut too much off
you can start over.
Drifting when tuned could be a coil heating up or bad joint or corona.
Remember there is more high current and high voltage with 160M antennas,
it is a different beast.
You may still need to add or subtract feed line length.
Small diameter coils like 2 inch OD heats up. With a cap in series and one
in parallel if you have open air variables, will arc over so 1/4 spacing
will be needed even when running 500 watts.
Adding more wire on antenna with a slight shift in frequency appears to me
the antenna is coupling into electrical wiring or some thing. If your QTH
like 7 miles from a BC station your reading on and MFJ analyzer will not
handle it. Swamping about 50 ohms across the analyzer then try to find a
resonate point may help.
Most baluns from what I have found do not have the right core material to
handle 160M so you use air wound coils to accomplish the same thing. 3
inch diameter coils seams to be the best even though you read people use 2
inch, maybe 2.5 inches OD. I have a 5 inch OD, if you use the antenna on
all bands the larger diameter coils do not work like you would think, you
may have to just disconnect all the external matching and just let your
tuner do the work inside the shack.
If you wind your own coils use # 14 or 12 gauge wire, 30uH would bee a good
start.
On Mon, Oct 14, 2013 at 10:22 AM, Jim GM <jim.gmforum@gmail.com> wrote:
> Hi Mike, WB8VGE
>
>
> Oh I all ways forget some things to say or ask.
>
> Does your antenna have traps? Is it fedd with open feed line or a single
> coax cable?
>
> Jim, K9TF
>
>
> On Mon, Oct 14, 2013 at 10:09 AM, Jim GM <jim.gmforum@gmail.com> wrote:
>
>> Hi Mike, WB8VGE
>>
>> Hope your surgery goes well for you.
>>
>> I have gone and still going thru issues with my inverted L on 160M like
>>
>> your having.
>>
>>
>> How long is your antenna? Is it a dipole or Folded dipole? I did not see
>> on your post the answers to these questions.
>>
>>
>> How high do you have it?
>>
>>
>> Your going to find or have found that the tuner you have and other tuners
>> will not work on 160M. They just cannot handle a near 50 ohm match or less
>> no matter what they claim. All they want is your money.
>>
>> So you need to add additional matching out side the shack with coils and
>> homemade capacitors made from coax cable, thats if you have a limited junk
>> box like I do.
>>
>> Any ways the external matching will aid your tuner in the shack to take
>> care of the rest.
>>
>> It will take some time and it is not a quick fix.
>>
>>
>> --
>> Jim K9TF
>>
>
>
>
> --
> Jim K9TF
>
--
Jim K9TF
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