[UK-CONTEST] [Fwd: Re: Ferromagnetics Choke Baluns]

[David, G3YYD]

Bob

With a less than a perfect ground screen (or more likely a very poor 
ground screen) then the outer of the coax will have a lot of RF current 
on it. Fitting a choke to the coax, AKA a choke balun, will help to 
reduce RF in the shack. Personally I do not use one but then my 160m 
vertical has a reasonable ground screen with the coax running underneath 
the ground screen.

For those who are mystified by my terminology of ground screen this is a 
more accurate description of what we are trying to do with something we 
normally call an earth. In other words screening as much RF current from 
the lossy earth as possible.

David G3YYD

Bob Henderson wrote:
> Hi Jim
>
> I hope you don't mind me asking but why would you be thinking of using a
> balun to feed unbalanced antennas such as the HF2V or an inverted L?
>
> Bob, 5B4AGN
>
> 2009/11/12 MM0BQI <MM0BQI at blueyonder.co.uk>
>
>   
>> Hi
>> I have two of the above but can find nothing on the web about them other
>> than I believe they were made by a Welsh company.
>> They are approx 11 inches by one inch, white plastic tubes with
>> 'Ferromagnetics Choke' written on them.
>> Both have an SO239 sockets at one end.  At the other end one has a short
>> pigtail of RG58 to a PL259 and the other has two screw terminals (possibly
>> for a dipole)
>> Does anyone have any info on them, frequency range/ power etc?
>> Possibly looking to use them on a topband inverted L and HF2V for 40/80.
>> Thanks
>> Jim
>> MM0BQI
>>
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