[TenTec] Antenna is up, but the coupler doesn't like 160 meters

[Bob McGraw - K4TAX]

Based on these numbers, the antenna should show resonance at about 1.8 MHz 
and the feedline should show resonance at about 2.75 MHz.  Let me emphasize 
that these are resonance numbers are not anyway related to SWR values.  With 
an instrument such as the MFJ 259 analyzer being operated as a dip meter, 
you should see a dip at or close to these two frequencies.  Again, disregard 
any SWR value at this point as it is a ratio of impedance and has nothing to 
do with resonant frequency.

If you are using something like a Tentec 238 or 239 tuner, connect the 600 
ohm line direct to the tuner terminals and be sure to have the jumper in 
place from Single Wire terminal to one terminal of the Balance Line 
terminals.  Also for 160M you will likely need the 1000 pF cap from the 
External Cap terminal to ground.  Especially true of the lower SWR/match 
takes place with the impedance switch on the low side.  This is a true 
trial-and-error determination.  I've found that 160M antennas are more 
problematic in terms of attaining a match than most any other band.

If you have several tuners that will not match the load, then the likely 
choice is to change the length of the feedline some + or - 10 ft.

Procedurally with the 239 tuner, set the inductance to maximum value and the 
capacitor value to #2. Then switch between the Lo Z #1  and Hi Z #1 
positions noting which shows the lower SWR.  Alternate adjust the Capacitor 
and inductor for the lowest reading. Should the capacitor be maxed out then 
switch to the next value.

I do recall that some tuners have a reversed notation in that a capacitor 
value of 0 is maximum C while on others a value of 0 is minimum C. 
Personally, I looked inside the box to see where maximum C occurs and 
maximum L occurs with regard to the scaling and made notes accordingly.

In my case for 160M and the internal balun, the Z switch required selected 
values of 3, 4, or 5 depending on frequency while the L value is about 20 to 
24 on the 0 - 30 number scale.

73
Bob, K4TAX










----- Original Message ----- 
From: "Mike Bryce" <prosolar at sssnet.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Monday, October 14, 2013 4:52 PM
Subject: Re: [TenTec] Antenna is up, but the coupler doesn't like 160 meters


> Jim,
>
>
> The antenna is a doublet up 50 feet inverted vee style.
>
> It is feed with about 170 ish feet of 600 ohm open line.
>
> None of the couplers can find a tuning solution
>
>
> All other bands work fine
>
>
> Sent from my iPad at Aultman hospital.
>
> Mike wb8vge
>
>> On Oct 14, 2013, at 11:09 AM, Jim GM <jim.gmforum at 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
>> _______________________________________________
>>
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