Re: [TowerTalk] Balun Overheating?

["Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>]

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?
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk