[OKDXA] Feed Line Problems NOW BALUN RECOMMENDATIONS

[John G.]

Hi Kim,

You get to a question that I was getting ready to ask.  My only need for a 
balun is to try to keep the RF off of the coax shield.  Originally I have a 
4:1 voltage balun thinking I needed it for impedance transforming, but that 
was before I knew as much about antennas as I do today.  What is the best 
type of balun for this-the one with the ferrite beads over a run of coax, or 
the one with the wires running thru a torrid donut shaped device?

73 John AF5CC
----- Original Message ----- 
From: "Kim Elmore" <cw_de_n5op at sbcglobal.net>
To: "Oklahoma - DX news and information" <okdxa at mailman.qth.net>
Sent: Sunday, April 21, 2013 3:46 PM
Subject: Re: [OKDXA] Feed Line Problems NOW BALUN RECOMMENDATIONS


> Do you need an impedance transformer as well as a balun? If all you need 
> is a balun for coax, a 1:1 current balun (balances current rather than 
> voltage) is probably what you want.  If you need an impedance 
> transformation, you may want to use something purpose built for that.
>
> Array Solutions is a good bet: their stuff is pricey, but high quality. 
> They have baluns for various transformation ratios: 1:1, 1.5:1, 2:1, 4:1, 
> 6:1, 9:1, 12:1 and 16:1. They also carry an Unun in 1.5:1 and 4:1. DX 
> Engineering is a another good source.
>
>
>
> Or, you can roll your own; they aren't hard to make. For 1:1 current 
> baluns, a long string of ferrite beads on some coax, all sealed up, is 
> always a good bet, though these can become inefficient under conditions of 
> a large mismatch. In the end, since (ideally) you spend your time instead 
> of your money, it's a matter of what you have the most to spare. Sometimes 
> you spend just as much money PLUS your time, but there's still the 
> knowledge gained, which you might not have gotten otherwise. If you roll 
> your own and need an impedance transformer, I'd suggest a dedicated 
> Sevick-type transmission-line transformer followed by a 1:1 current balun.
>
> 73,
>
> Kim N5OP
>
> On 4/21/2013 9:29 AM, John G. wrote:
>> Thanks for the advice Roger.  Do you know what type of balun it was? 
>> Also, since I am going to be getting a new current balun, any 
>> recommendations as to brand?  One that is built to last?  I am only going 
>> to be running 100 watts
>>
>> 73 John AF5CC
>> ----- Original Message ----- From: "Roger Simpson" <rksimpson1 at cox.net>
>> To: <okdxa at mailman.qth.net>
>> Sent: Sunday, April 21, 2013 1:38 PM
>> Subject: [OKDXA] Feed Line Problems
>>
>>
>>> I agree that the problem is likely a bad connection, bad coax,  and/or 
>>> relay contacts that have corrosion/dirt.
>>>
>>> The problem I had once with a balun was not actually the balun itself. 
>>> It turned out to be the the wires from the balun were soldered to an 
>>> SO-239 and the wire from the balun to the outside of the SO-239 was 
>>> connected to a solder lug that was screwed down to the SO-239. In my 
>>> case I took the balun out of the old case and built a new case for it 
>>> out of some 2 inch PVC pipe with a couple of PVC pipe caps. Then I used 
>>> a new SO-239 and soldered the wires from the balun to the new SO-239. 
>>> This fixed my problem.
>>>
>>> The balun I am describing I originally bought back in the early 1980s. 
>>> It was up for about ten years before it started giving me problems. I am 
>>> still using the balun today on my 30m / 40m Inverted “V”. So the problem 
>>> was not with the balun itself, but with a flaky connection. These flaky 
>>> connections can definitely act differently on different bands. In some 
>>> cases a flaky connection can look like a leaky diode on certain bands.
>>>
>>> These cases are so difficult to trace that I think it is easier to just 
>>> replace stuff until the antenna works again. Also, these problems can be 
>>> so flaky that they are intermittent. So you might think something is OK 
>>> after checking and that have it to go back again later to its broken 
>>> state.
>>>
>>> The way I isolated that the balun was the problem was that I replaced 
>>> it. Once I knew that the problem was the balun I tore it apart to 
>>> discover the corroded connection to the SO-239.
>>>
>>> 73  Roger   K5RKS
>>>
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