[TowerTalk] Six meter balun

[Grant Saviers]

A minor matter, but RG142 center conductor is SCCS - silver plated 
copper coated steel.  That makes it very strong but fatigue prone.  Some 
are concerned about TFE creep from the solid conductor and recommend 
stranded RG400 as a result.  However, I've not had problems in FT-240 
toroid chokes wound 10 years ago with 142 made from Mil 17/60-RG142 spec 
cable.

Paternack specs their 142 at 2400w average power at 100MHz.  It will get 
hot, but the TFE handles it.  Best to provide easy dissipation of the 
heat as K9YC recommends.

Another possible issue is to keep ferrite toroids away from the boom and 
other conductors as the coupling can cause problems.

Grant KZ1W


On 7/2/2022 16:13, Jim W7RY wrote:
> Agreed.
> 
> RG-400 works well to. The only difference between RG-142 and RG-400, is 
> that RG-400 has a stranded center conductor. RG-142 has a silver plated 
> solid hard drawn copper center conductor.
> 
> 73, Jim W7RY
> 
> 
> On 7/2/2022 6:09 PM, john at kk9a.com wrote:
>> The 50MHz power average rating for RG142 is several kilowatts, why do you
>> think it is inadequate?*If it is a balun problem it is most likely 
>> connection related.*
>>
>> John KK9A
>>
>>
>>
>> Dave Sublette k4to wrote:
>>
>> My six element 6M LFA is showing a high SWR and severe loss of receive
>> signal.  This happened this afternoon as I was working the band with 500
>> watts from my KPA500.
>>
>> To this point, the antenna was very nicely matched with a 1:1 SWR over
>> almost 1 MHz of bandwidth. The antenna is home brew and I made the 
>> matching
>> balun per the instructions from K9YC using two toroids with six turns 
>> each
>> of high quality teflon insulated, double shielded silver braid. I 
>> think it
>> was RG142 purchased new from a reputable vendor in Tennessee. It has 
>> worked
>> perfectly at the 100 watt level for three or four years.  I had looked at
>> the specs on the coax and thought it would be good for 500 watts.
>> Evidently not.
>>
>>
>> 73,
>>
>> Dave, K4TO
>>
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