[Amps] Line Isolators for RF feedback

[R.Measures]

On Aug 3, 2004, at 9:40 AM, Joe Isabella wrote:

> Good point, Rich!!  I guess I should say "DUUHHH!!!".

Rube Goldberg showed up that high-tech solutions are not always mo' 
bettah.
>
> I would imagine that the coax and/or PL-259 would be the weak link in 
> this case though, wouldn't
> it??

PL-259 connectors are always the weak link because they allow water and 
water vapor to enter the coax.

> Even say RG-400 or RG-303 would give up before they get saturated, 
> right?

Hello, Joe --  Coax doesn't saturate, it melts and/or ignites.  Cores 
saturate.

> Just curious --
> even if I ran my 3K-A at full bore, it wouldn't kill 'em (given that 
> the dipole is at it's
> resonant point).

A 3K-A will do about 2-out.  This should not be a problem for small 
coax using SSB, especially because the choke balun is at the center of 
the dipole - so it gets cooled by the breeze.  I make the choke balun 
for a dipole out of the same coax used in the feedline because there 
are no coax splices or connectors out in the weather and because the 
balun would definitely be as capable as the feedline.  Sure, an 
ugly-balun won't win any beauty contests, but it  Will  do the job.  // 
  The main weakness of an outdoor coax choke balun is that UV from the 
sun deteriorates the nylon cable ties that are used to hold the coax to 
the ABS sewer pipe.  A solution is to cover the nylon cable ties with  
black electrical tape.
end
>
> Joe
>
> --- "R.Measures" <r at somis.org> wrote:
>
>>
>> On Jul 31, 2004, at 10:21 AM, Joe Isabella wrote:
>>
>>> The one I use has ferrite beads stacked on top of each other (about 
>>> 50
>>> of the little buggers!!) on
>>> about a 12 inch piece of teflon coax.  Since it isn't a torroid, it
>>> can't be saturated.
>>
>> One wire through the center of a ferrite bead is a one-turn toroid.
>> And yes, given enough current and freq., they can be saturated.  The
>> only coax choke device that can not be saturated has an air-core or
>> powdered-iron core.
>>
>>>  It'
>>> supposed to handle 5kW, but I haven't quite hit it with that much
>>> power yet ( :-)  ).  It totally
>>> fixed all my RF woes, and I had plenty!!
>>>
>>> Joe,
>>> N3JI
>>>
>>> --- Alek Petkovic <vk6apk at eon.net.au> wrote:
>>>
>>>> Ditto for me downunder.
>>>>
>>>> The Radioworks line isolators do the trick nicely.
>>>>
>>>> You can make your own as they are just coax wound around a ferrite
>>>> rod. You
>>>> can also use the coil of coax like Rich suggests.
>>>>
>>>> They all work well  but the RadioWorks product is very neat and
>>>> convenient
>>>> to use. It is nicely encapsulated with the female connectors on each
>>>> end.
>>>> Makes it real easy.
>>>>
>>>> 73, Alek
>>>> VK6APK
>>>>
>>>> ps: Their wire antennas are well made and work quite ok as well.
>>>>
>>>> At 12:19 PM 30/07/2004, Harold B. Mandel wrote:
>>>>> Seconding the message below I add my personal endorsement
>>>>> to Radio Works.com.
>>>>>
>>>>> When moving my shack from the 12 month "dxpedition" in
>>>>> Secaucus, New Jersey to my home in Kentucky, a severe case
>>>>> of RF feedback plagued the station when activating a linear
>>>>> amplifier.
>>>>>
>>>>> Even though I was ready to plunk down cash for goodies, Jim, W4THU,
>>>>> took time to speak with me at length, and suggested several tests
>>>>> to further diagnose the culprit and refused to sell me anything 
>>>>> until
>>>>> reporting back to him.
>>>>>
>>>>> I found out about Radio Works when up in new Jersey, and purchased
>>>>> line
>>>>> isolators to cure RF feedback going into the hotel telephone 
>>>>> system.
>>>>>
>>>>> Score for Radio Works: AAAAA+
>>>>>
>>>>> Hal Mandel
>>>>> KA1XO
>>>>> On Tue, 27 Jul 2004 07:34:28 -0500 "Gene Bigham" 
>>>>> <jbigham2 at kc.rr.com>
>>>>> writes:
>>>>>> I followed Radio Works recommendations for RF feedback problems.
>>>>>> Their line isolators and grounding ideas worked to cure a bad case
>>>>>> here.
>>>>>> _______________________________________________
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>>>>>>
>>>>>>
>>>>> _______________________________________________
>>>>> Amps mailing list
>>>>> Amps at contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>
>>>> http://www.qrz.com/vk6apk
>>>> http://profiles.yahoo.com/vk6apk
>>>>
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>>>>
>>>
>>>
>>>
>>> 		
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>>>
>> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>>
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>
>
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org