[SCCC] Antenna Challenge

[Mark Schoonover]

Glenn and Mike,

Thanks for the ideas. I've tried most of them already. I did make a
run to the candy store after work and picked up a W2DU current balun.
After thinking about it, the one I bought 15 years ago was good from
3.5-30 MHz. No difference. I tried the W2DU between at the antenna and
between the tuner and rig. No luck. I tried clamp on filters for the
DC cable at one time w/o any difference. I decided to put a SWR bridge
between the rig and tuner and it confirms the SWR meter in the rig. I
think there's something up with the tuner and I've pulled it offline
and will use the built-in tuner for the contest. I'll plan on sending
it back to LDG to take a look at it.

Yes, it's CQ 160 not ARRL 160. ARRL 160 was when I discovered this problem. :(

Thanks again!

73! Mark KA6WKE

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On Thu, Jan 24, 2019 at 10:04 AM Glenn Rattmann <k6na at cts.com> wrote:
>
> (Mark, you mean CQ 160 and not ARRL 160...)
> I agree with Mike's thoughts.
> I would also put some clamp-on beads on the RG213 from radio to input of tuner.
> If you don't have those available, replace the coax driveline with
> one much longer than the short one you have in there.
> Coil up the excess coax to make a common-mode choke (6-8 inch
> diameter coil bundle, so you need 1.5 - 2ft per turn).
>
> Good luck!
>
> Glenn K6NA
>
> At 09:20 AM 1/24/2019, Michael Tope wrote:
> >This is a longshot, Mark, but I wonder if LDG is trying to match
> >your antenna at a harmonic of the input frequency. Do you happen to
> >have a standalone impedance analyzer (e.g. an MFJ-269) that you
> >could use to sweep the input of the LDG after it tunes up (with the
> >IC-7600 driving it) and indicates the 1.3:1 VSWR across 160 meters?
> >
> >You mentioned putting ferrites on the lines going to the rig. What
> >about the line carrying the +12V power going to the LDG?
> >
> >How is the connection between the tuner and the antenna (i.e.
> >shorted twinlead) and the ground radials configured? Do you have a
> >short piece of coax running to the feedpoint where the radials and
> >the shorted twinlead come together? Is there a current balun (i.e.
> >RF choke) on that coax to help keep the coax outer conductor and
> >tuner chassis from becoming part of the radial system?
> >
> >73, Mike W4EF................
> >
> >On 1/23/2019 8:57 PM, Mark Schoonover wrote:
> >>Good evening,
> >>
> >>Hoping the collective of SCCC can give me some assistance. I'm looking
> >>at participating in the ARRL 160M contest this weekend. The antenna is
> >>a 33' of shorted ladder line with a 40M full wave loop at the top
> >>antenna. I put down as many radials as I could, some are close to 1/4
> >>wave on 160 but most are lucky to be 1/4 on 40.
> >>
> >>I have an IC-7600 attached to a LDG 1000proII tuner. I can get a good
> >>match all across 160M <1.3:1 on the tuner's built-in SWR meter but the
> >>meter on the rig is >3:1 and power folds back. I have the tuner right
> >>next to the rig with RG-213 from DXE between the two. There's 1" braid
> >>from tuner->rig->ground rod outside. When I take the LDG out of line
> >>and use the rig's built-in tuner, I can get 1.4:1 across the band.
> >>
> >>I initially thought it was RFI getting back into the rig because the
> >>antenna is about 5' from the radio desk. I put mix 43 chokes on every
> >>cable entering the rig. No luck on that front but it sure did reduce
> >>RFI.
> >>
> >>So any ideas what this could be? I'm scratching my head on this one...
> >>
> >>Thanks for reading!
> >>
> >>73! Mark KA6WKE
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