[Boatanchors] Ferrite Choke

[mac]

Hi Gary, it's ben a while....

Yep, I know all that.  Special considerations concerning radiation  
pattern,noise or
RF feedback existing or anticipated then OK.  For normal Ham  
installations, though, just give it a
simple first try and maybe save yourself some effort and expense.  In  
my personal experience
baluns, ferrite beads and tubes, etc. at wire antenna feed points or  
not never made
a significant difference in what I could hear and who I could work.

In the game since 1951

Dennis D.  W7QHO
Glendale, CA

***************
On Jul 15, 2012, at 6:05 PM, Gary Schafer wrote:

>
>
>> -----Original Message-----
>> From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-
>> bounces at mailman.qth.net] On Behalf Of Ron Youvan
>> Sent: Sunday, July 15, 2012 8:30 PM
>> To: boatanchors at mailman.qth.net
>> Subject: Re: [Boatanchors] Ferrite Choke
>>
>>   Dennis D.  W7QHO  mac wrote:
>>
>>> Might be interesting to put the antenna up without any choke or
>>> ferrite and see how it works out......
>>
>>
>>   That is all that existed B 4 antenna baluns were created.
>> The advantage of any kind of balun at the feed point of a dipole is  
>> to
>> prevent a nearby object to
>> one half of a dipole from unbalancing the antenna.  If it is equal
>> lengths and really in the free
>> and clear it does nothing of any great use.  Baluns can be made with
>> powered iron also cores.
>> --
>>    73 Ron KA4INM
>
> Consider that a coax cable feeding an antenna is actually 3 wires.
> Two inner conductors (center wire and the inside of the shield) and  
> the
> third conductor is the outside of the coax shield.
>
> When connected to a balanced antenna, the center conductor is  
> connected to
> one side of the antenna and the other side of the antenna is  
> connected to
> the inner shield and the outer shield.
> That makes the antenna have one leg on one side and two legs on the  
> other
> side, one being vertical (the coax).
>
> This unbalances the antenna and causes current to flow on the outer  
> shield
> of the coax which acts as part of the antenna.
>
> It may work very well in this configuration as many have for lots of  
> years.
> The disadvantage is the vertical part can pick up more noise and put  
> RF back
> into the shack on transmit. It disrupts the dipole pattern if you  
> care about
> that.
>
> The commonly used balun acts as a choke to isolate the outer coax  
> shield
> from the leg of the antenna that is connected to the shield.
>
> 73
> Gary  K4FMX
>
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