[TenTec] OT 75 Ohm twin feeder

[Fraser Robertson]

Thanks all for the interesting comments re wet twin feeder.  Come to think of it, our club has an 80m doublet fed with 200' of 450R slotted line, and that needs re-matching when it's wet. 
 
The 20/15/10m parallel dipole twin feeder was only about 30' long, but since I wasn't using an ATU the swr change was a problem.
 
I admit I hadn't given the additional losses much thought. 
 
73 Fraser G4BJM
> Date: Wed, 18 Jun 2008 08:45:01 +0100> From: steve at karinya.net> To: tentec at contesting.com> Subject: Re: [TenTec] OT 75 Ohm twin feeder> > Hi Fraser,> > I have some of Westlake's "400W 75 Ohm twin" where both conductors are > totally embedded within the dielectric material. Assuming the field > between the conductors is mostly constrained to the dielectric, I > wouldn't expect much effect from rain. I've never had any of his Heavy > Duty stuff so I don't know whether the same would apply.> > But you raise an interesting point, and I'm wondering whether the same > problem might occur with my twin RG400 configuration. Time to go and > spray the test assembly with water from the rain butt! If there is a > problem I can always put the feeder within the HexBeam centre post - it > just takes a bit more effort!> > 73,> Steve G3TXQ> > Fraser Robertson wrote:> > Hi Steve et al. Some years ago I put up horizontal parallel dipoles for 20/15/10m and wanted to feed them with heavy duty 75R twin feeder to avoid the weight of a centre balun and coax. Westlake no longer stocked HD 75R twin but said their black/red DC power cable worked as a substitute. I found this did indeed work ok, with a balun at the bottom end, except whenever it rained the swr shot up. Question: does rain have a similar effect on 'proper' 75R twin.73 Fraser G4BJM> > > >> > _______________________________________________> TenTec mailing list> TenTec at contesting.com> http://lists.contesting.com/mailman/listinfo/tentec
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