Don, you did not tell us what band(s) you are having this problem on.
The problem is most likely due to common-mode current on the line.
In this situation, the 12 ft. of coax is about 1/5 wavelength on 20m.
That's because the VF of the coax only pertains to the current flowing
inside the coax.
Common mode current is flowing on the outside of the shield where the VF is
about 0.98, not 0.66.
Insert a common-mode-current choke (RF choke) between your ATU and the
balun.
The ones sold by The Wireman are very good for this purpose.
BTW, in case the problem is occurring when trying to load it on 40 or 80m,
that is due to the balun.
Replace it with a 1:1 current balun and your problem will most likely
disappear.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Don Jones
Sent: Saturday, September 13, 2014 4:13 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Zepp?
I am using a 34 ft doublet / zepp for 20M and above. I feed it with 100ft of
#16 420 ladder line that can be purchased from radio works. I am using a 4:1
DX Engineering 10kW-pk rated balun.
The antenna is 34 ft high and works pretty good. I am happy with my
shortened zepp.
One strange misbehavior I have found that my MFJ 929 auto tuner lockup if
placed near the 4:1 balun (i.e. using a 2 ft jumper of RG213).
requiring power to be cycled to regain its brain.
With a 12 ft length of RG213 (about a 1/4 wave long @ 20M) between the
remotely mounted tuner and balun, it works fine up to 28.3MHz. I have not
grounded the case of the balun yet, going to try that next.
The auto tuner is installed inside a spare 50 cal ammo can I had kicking
around to protect it from the elements. Come to think of it, a EMI gasket
vendor dropped off some rubberized EMI Gaskets at my lab, I think I will
install some of that stuff and see if that solves my problem.
73, Don KO7i
On 9/10/2014 8:59 AM, Joel Hallas wrote:
> That's what I mean by "at the bottom," at the bottom of the feed line
> rather than at the top where the antenna is. The SWR is not improved,
> but the loss is reduced.
>
> Regards, Joel Hallas, W1ZR
> Westport, CT
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Paul
> Gates via TenTec
> Sent: Wednesday, September 10, 2014 11:29 AM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Zepp?
>
> I do not know what you mean by putting Balun at bottom? I place my
> balun between the openline and the tuner. 130 ft attenna then the SWR
> is 1:1 on all bands.
>
> Paul Gates KW4BD
>
>
> On Wednesday, September 10, 2014 10:46 AM, Joel Hallas
> <jrhallas@optonline.net> wrote:
>
>
>>
>> Gents,
>>
>> This is an interesting antenna idea, and I did a quick EZNEC/TLW look
>> on the
>> 5 major HF bands. Unfortunately, the SWR ranges from a low of 5:1 (80
>> and 10
>> meters) to 11:1 on 40. 100 feet of RG-213 will have a loss of more
>> than
>> 2 dB on all bands, except about 1 dB on 80.
>>
>> An alternative, and what I am using here, is to feed the 130 foot cf
>> antenna with lower loss window line and a balun at the bottom, with a
>> short length of coax to a tuner. Window line is lighter (less sag),
>> cheaper and has less loss than coax.
>>
>> The same discussion about names could take place in the window line
>> realm <g>!
>>
>> Regards, Joel Hallas, W1ZR
>> Westport, CT
>>
>>
>> -----Original Message-----
>> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of John F.
>> Sent: Wednesday, September 10, 2014 10:16 AM
>> To: tentec@contesting.com; Jim Allen
>> Subject: [TenTec] Zepp?
>>
>> Jim,
>> I like the sound of Zepp better than dipole. Actually it's probably
>> a matter of semantics, and I'm not going to argue how many angels
>> will fit on the head of a pin! ;>) There is a reason I called it a
>> zepp, and I think it was in the 95 or 98 Handbook. Terms many have
>> changed by
> now.
>> I actually think it's a dipole only on 80 meters, and technically a
>> doublet on the other bands! Ooops, I did it!
>>
>> 73,
>> John, K4AVX
>>
>> Yes the balun, I think is a 9 to one. It will load and put out a
>> signal on all bands except 160 meters. Trying to work out an
>> inverted L again on that band - tricky.
>>
>>
>>> Message: 3
>>> Date: Tue, 9 Sep 2014 15:46:59 -0500
>>> From: Jim Allen<jim.allen@longhornband.net>
>>> To: Discussion of Ten-Tec Equipment<tentec@contesting.com>
>>> Subject: Re: [TenTec] Eagle Tuner
>>> Message-ID:
>>>
>>> <CAO5v6iLk96Oi-DVfpCPLpO35MphtsfoFD7K4MUvGOP9wPokQEw@mail.gmail.com>
>>> Content-Type: text/plain; charset=UTF-8
>>>
>>> What makes a 130' center fed dipole a Zepp?
>>>
>>> 73 de W6OGC Jim Allen
>>>
>>> On Tue, Sep 9, 2014 at 3:44 PM, Rick - DJ0IP / NJ0IP<Rick@dj0ip.de>
>> wrote:
>>>> That is an excellent setup, John. Nice choice.
>>>>
>>>> I'm a friend of that antenna too and have used it most of the time
>>>> for the past 50 years.
>> _______________________________________________
>> 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
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|