Bob is fully correct. It would be much better to use a 1:1 balun.
I think the 4:1 DX-E balun is a current balun (not certain); if not then it
is totally out of place for this job, regardless of what anyone working for
DX-E might have told us.
If it is a current balun, then it will only impede common mode current
adequately enough if the SWR is below about 4:1. Better when it is lower
than that.
However, I did not jump immediately onto the 1:1 balun bandwagon because the
impedance of the antenna on 10m (without consideration of the impedance
transformation due to the feedline) is about 2000 Ohms which may be beyond
the range of the specific MFJ tuner in use, if we use 1:1. In that case,
the cmc would not be a problem when using a 1:1 balun, but the matchbox
would not find a match. But there's an easy work-around.
That's why we need to know the frequency.
If you are familiar with the DX-E portfolio of baluns, then you will know
that they were either designed or specified by Tom Rauch, W8JI, who like
G3TXQ (and me), insist that the best balun to use in front of the tuner is a
1:1 Guanella balun. Both Tom and Steve explain why on their own web pages.
If your matchbox can't cope with the higher impedance when using a 1:1
balun, then that's a matching problem, not a balun problem. You can adjust
the feedline length, or add a second device, either a step-up transformer or
a 1:4 balun. In this case it is OK to use a 1:4 voltage balun because the
cmc impeding is being handled by the 1:1 current balun.
Unfortunately when you speak with some sales persons at DX-E, you don't
always get good advice. Some will still recommend a 4:1 balun. Tom
designed their portfolio but doesn't work there. You won't get him on the
phone.
Final note: is it 4:1 or 1:4? Gosh I don't know.
Sevick defined it one way, but the vendors selling these devices call it the
other way. Let's forget the semantics and specify exactly what we are
talking about: the 50 Ohm side is towards the TX and the 200 Ohm side is
towards the antenna.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Bob McGraw
- K4TAX
Sent: Saturday, September 13, 2014 11:00 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Zepp?
My first thought is one should be using a 1:1 balun which would be a current
balun and not a 4:1 voltage balun. The described antenna would likely have
a feed point Z of about 75 ohms, based on length and height. Feeding with a
non resonant feed line the impedance would appear similar at the
transmitter/tuner end.
Based on your description the impedance seen by the tuner is some 18 ohms.
Fact is known, a tuner a very low Z load presents higher tuner loss. I also
suggest a common mode choke between the tuner and the balun.
73
Bob, K4TAX
----- Original Message -----
From: "Don Jones" <ko7i@comcast.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, September 13, 2014 9:12 AM
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.
>>> _______________________________________________
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>>> TenTec@contesting.com
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>>>
>>>
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>>>
>>>
>>>
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>>
>>
>
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