[TowerTalk] Balun Overheating?

[Roger (K8RI) on TT]

On 4/21/2014 1:59 AM, Grant Saviers wrote:
> I melted the commercial "HD QRO" bead type choke off my GOTA G5RV 
> feedline junction and since then only use the FT-240-31 cores stacked 
> 3 or 4 at QRO with TFE coax (RG142 double silver) turns or the "big 
> clamps ons" type 31 at up to 500w with RG8X, very convenient.  Why use 
> beads when inductance is proportional to turns squared?  A much better 
> use of ferrite is a larger core with the appropriate turns per K9YC or 
> G3TXQ's data.
>
> Never again G5RV's, fan dipoles rule!

This is what I use on 75.
http://www.rogerhalstead.com/ham_files/AntennaFeed2.htm

73

Roger (K8RI)


> Grant KZ1W
>
>
> On 4/20/2014 9:24 PM, Roger (K8RI) on TT wrote:
>> On 4/20/2014 10:26 PM, Jim Lux wrote:
>>> On 4/20/14, 6:34 PM, Tom Hellem wrote:
>>>> Fellow TTers:
>>>>
>>>> I built a balun for my triband yagi consisting of 50 type 73 
>>>> ferrite beads
>>>> slipped over a piece of RG 303
>>>> coax, enclosed inside of a piece of 1-1/2" pvc. Had one of the 
>>>> wires break
>>>> inside and I surmised it must have
>>>> been a result of wind-caused vibration, etc. So after I repaired 
>>>> the broken
>>>> connection, I squirted some of that
>>>> canned foam insulation (the kind that is sold for foaming around 
>>>> windows &
>>>> doors, etc.)into the pvc enclosure,
>>>>   encasing the entire piece of coax & ferrite beads in the stuff 
>>>> thereby
>>>> preventing any vibration , etc in the future.
>>>> Upon further thought I am wondering now did I invite the balun to 
>>>> overheat,
>>>> especially while running high power,
>>>> as any heat generated has no way to escape.
>>>> Does anyone have an opinion one way or 'tother?
>>>>
>>>>
>>>
>>>
>
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