bob,
since the antenna is inverted vee style, the feedline slopes away from the
tower.
and yes, 5kw current 1:1 balun at the end feed into the 238 tuner.
Mike Bryce, WB8VGE
the heathkit shop
SunLight energy systems
J e e p
o|||||||o
On Oct 14, 2013, at 10:58 PM, Bob McGraw - K4TAX wrote:
> Diddling a bit more, the feed point Z of the antenna is projected to be
> around 20 to 25 ohms. The feed line is about 3/8 wavelength or about 135
> degrees. I see nothing wrong with these values that might point to an issue.
>
> I will presume the feedline is brought away from the antenna at near 90
> degrees and is not running parallel with the antenna. This could create a
> problem should he feedline be basically parallel with the antenna.
>
> Hopefully you are using a 1:1 current balun and not a 4:1 current or voltage
> balun. If you are using a 4:1 balun, I suggest turning it around in the
> circuit such that it is operating as a 1:4 balun. If you are using the
> configuration as a 4:1 balun, with a Z on the output side at some 20 ohms,
> then tuner is seeing something like 5 ohms. Thus finding the Z to be outside
> of the matching range of the tuner.
>
> Just a few thoughts and ramblings.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message ----- From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Monday, October 14, 2013 7:27 PM
> Subject: Re: [TenTec] Antenna is up, but the coupler doesn't like 160 meters
>
>
>> 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@sssnet.com>
>> To: "Discussion of Ten-Tec Equipment" <tentec@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@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
>>>> _______________________________________________
>>>>
>>> _______________________________________________
>>> TenTec mailing list
>>> TenTec@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/tentec
>>>
>>
>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|