[Boatanchors] Ferrite Choke

Mon Jul 16 14:05:34 EDT 2012

Dont remember seeing anything from you last week, however Ive been aware of 
the article since it was published in 2006 since Im a YCCC member.
There are also updates to it.

----- Original Message ----- 
From: "J. Forster" <jfor at quikus.com>
To: "Geoff" <geoffrey at jeremy.mv.com>
Cc: "mac" <w7qho at aol.com>; <garyschafer at comcast.net>; 
<boatanchors at mailman.qth.net>
Sent: Monday, July 16, 2012 11:35 AM
Subject: Re: [Boatanchors] Ferrite Choke

>I guess you now acknowlege "a good paper on the subject that goes into a
> lot of detail" that I posted here LAST WEEK:
>
> "---------------------------- Original 
> Message ----------------------------
> Subject: Re: [Boatanchors] Ferrite Choke
> From:    "J. Forster" <jfor at quikus.com>
> Date:    Fri, July 13, 2012 1:25 pm
> To:      "Jim Wiley" <jwiley at alaska.net>
> Cc:      "Keith Densmore" <kmd at xplornet.ca>
>         boatanchors at mailman.qth.net
> --------------------------------------------------------------------------
>
> A 'sleeve-type balum' may need a lot more than ten.
>
> http://ebookbrowse.com/baluns-w1his-pdf-d286062338
>
> -John
>
> ==============="
>
>
>
>
>
>> As Im sure Gary is aware there is a lot more to creating a good common
>> mode
>> choke than just winging it without understanding what is involved.
>>
>> Ive had good results with a HP-4815A Vector-Impedance meter. By good I
>> mean
>> acceptable to my needs realizing the possible measurement errors from
>> strays.
>>
>> Here is a good paper on the subject that goes into a lot of detail. There
>> are errors in his measurements that have been covered elsewhere and the
>> number of the large ferrite toriods can be substantially reduced.
>>
>> http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf
>> ----- Original Message -----
>> From: "mac" <w7qho at aol.com>
>> To: <garyschafer at comcast.net>
>> Cc: <boatanchors at mailman.qth.net>
>> Sent: Monday, July 16, 2012 12:03 AM
>> Subject: Re: [Boatanchors] Ferrite Choke
>>
>>
>>> 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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