Hello Peter,
Try posting this on the RFI reflector as well.
I'm sure there will be some suggestions.
73!
Tim K3LR
"Peter Dougherty (W2IRT)" wrote:
> Hi guys,
>
> This afternoon my tower guru replaced an 80m monoband dipole with a
> TV Evans 3-band dipole for 40/80/160 at my house, and it looks like
> I've just opened a can of RFI-flavored worms.
>
> The old dipole was a full-sized homebrew antenna, fed through a W2DU
> current balun via about 100 feet of RG-213. It worked "OK" on 80
> (nothing to write home about). Although I could achieve a match
> through a tuner on 40 and 160, it was worse than useless on those
> bands, of course. With the tuner, I could get it to work OK on 80 CW.
>
> So, this came down and the new Evans dipole went up. From a common
> centre insulator (too small to be a voltage balun or current balun),
> there are two wires off each side -- one is a full-sized dipole for
> 80m and the other is a full-size 40, then a resonator and an extra
> bit of wire for 160. This is fed with the same coax that the old
> monoband dipole was fed with.
>
> Right now it's resonant in the middle of the SSB DX window on 80 but
> not on 80 CW (obviously), 160 or 40 (both need to be pruned somewhat
> for the latter two bands). I keyed up on 40 CW (with a flat SWR) and
> noticed massive key clicks coming through my computer speakers and
> the lamps inside my Ten-Tec 238 tuner were lighting 3 times their
> normal brightness on key-down. Uh Oh.
>
> Looks like a matter of hours before the neighbours break out the
> pitchforks and torches, so I've gotta get to the bottom of this and fast.
>
> Last time I ran into something like this was also on 40 at my old
> QTH, with my old Alpha-Delta DX-EE. I never could run it on 40
> without an MFJ "artificial ground" in my old apartment building, and
> even then, it was of limited use. Seems to me, that 40 is a problem
> band for RFI for me. Now, there is no current balun on the new
> antenna (not enough coax to make a coax balun either), but I'm not
> sure if I'm dealing with radiation off my feedline or what. The
> feedpoint of the antenna is at the back of the house (near the shack,
> about 25' away horizontally and up 70') and the wires run across the
> back and side yards to trees.
>
> There's a 3/4" braid from the shack going to a ground rod right
> outside (relatively short run), and connected or not, it makes
> absolutely no difference whatsoever - as has always been my
> experience with grounding, incidentally.
>
> Unfortunately I can't climb (no equipment plus I've never done it in
> my life before -- and I'm not in the kind of physical condition which
> would allow it, either), so I really don't know what I can do short
> of going QRT below 30m permanently -- and that's really not an option
> I want to think of. If there's anybody in northern NJ who may be able
> to help me engineer a better solution than I have going here, I'd do
> just about anything to make this happen.
>
> - Peter
>
> W2IRT
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
> questions and ask for Sherman, W2FLA.
>
> _______________________________________________
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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