Exactly! You have a lot of loss in your ground (or something), Todd.
Perhaps it's the lack of a proper feedline choke.
73, Mike
www.w0btu.com
On Sat, Dec 29, 2018, 11:00 AM Grant Saviers <grants2@pacbell.net> wrote:
> Problem #1. The swr indicates about a 140Khz plus < 2:1 bandwidth (2 *
> 1880-1810) which implies a high radial resistance. Are the elevated
> radials fully insulated from trees, not contacting foliage, etc? Add
> three more.
> Problem #2. Your coiled coax choke may be making things worse. Check
> out the just released designs from K9YC and build one. 17 turns RG400
> on one FT240-31.
> Problem #3. The increased gain of the T may be causing BCB desense of
> the 7300. You need a BCB filter. Also the poor choke may be letting a
> lot of common mode noise into the antenna.
>
> Grant KZ1W
>
>
>
> On 12/28/2018 19:39 PM, Todd Goins wrote:
> > A person emailed me to ask if I could take SWR readings at the rig
> without
> > a tuner. Since my antenna analyzer is non-op due to the AM station
> nearby.
> > The feedline is about 140' of LMR-240.
> >
> > Here is the indicated SWR at the 7300:
> > 1.810 1.2:1
> > 1.830 1.3:1
> > 1.850 1.5:1
> > 1.870 1.8:1
> > 1.900 2.3:1
> > 1.940 3.0:1
> >
> > Todd - NR7RR
> >
> > On Fri, Dec 28, 2018 at 7:30 PM Todd Goins <tgoins@gmail.com> wrote:
> >
> >> Charlie,
> >>
> >> Yeah, I know the 100w is not ideal. This is night #2 with the elevated
> >> radials on the 100' vertical. I spent every day last week trying to use
> the
> >> 100' vertical against my buried radial field. It was horrible on
> transmit
> >> and mostly deaf (high noise) on receive. The attenuator didn't help, it
> >> just isn't hearing stations. My 43' vertical top loaded with 90' of
> >> horizontal wire is way, way more effective.
> >>
> >> I'm using a 230' BOG as my primary receive antenna right now but I can
> >> switch in the transmit antenna to listen just by throwing a switch.
> >>
> >> I'll stick with this 100' antenna for a while and try to use it this
> >> weekend on the Stew Perry but I have a feeling I'll be back with the 43'
> >> before it is over.
> >>
> >> Thanks,
> >> 73
> >> Todd - NR7RR
> >>
> >> On Fri, Dec 28, 2018 at 7:19 PM charlie carroll <k1xx@k1xx.com> wrote:
> >>
> >>> Todd:
> >>> So, I might shorten the antenna up a bit to get the lowest SWR point a
> >>> bit higher in the band. But, as it sits right now, your SWR is not
> >>> indicating a problem. You're talking only a 100 watts which gives you
> at
> >>> least 1 strike. I would play with it as is for a few days and get some
> >>> idea as to how well you are hearing and how well you are transmitting.
> >>>
> >>> Without detailing you, 160 is a place where you need patience and/or a
> >>> low-noise receiving antenna. Plus, you also need to know whether you
> are
> >>> being affected by local noise sources. Another reason why I encourage
> you
> >>> to spend more time evaluating the antenna.
> >>>
> >>> 73 charlie, k1xx
> >>>
> >>> On 12/28/2018 10:07 PM, Todd Goins wrote:
> >>>
> >>> Hi Charlie,
> >>>
> >>> I can measure SWR at the rig. Feedline is about 140' of LMR240 coax.
> >>>
> >>> SWR at:
> >>> 1.810 1.2:1
> >>> 1.830 1.3:1
> >>> 1.850 1.5:1
> >>> 1.870 1.8:1
> >>> 1.900 2.3:1
> >>> 1.940 3.0:1
> >>>
> >>> I wasn't too worried about the choke situation but I connected in-line
> >>> what I had on hand, figured it wouldn't hurt. Mike had just asked what
> I
> >>> was using so I let him know. I'm not having any symptoms of RF in the
> shack
> >>> but I'm only running 100 watts.
> >>>
> >>> 73,
> >>> Todd - NR7RR
> >>>
> >>>
> >>> On Fri, Dec 28, 2018 at 6:56 PM charlie carroll <k1xx@k1xx.com> wrote:
> >>>
> >>>> Todd:
> >>>> So, what do you expect the air-wound choke to do for you? Many, many,
> >>>> many antennas operate fine without a choke. Don't get yourself
> wrapped
> >>>> around the axle that the antenna won't work without a "correct" choke.
> >>>>
> >>>> What's SWR are you measuring at the transmitter? How long is the
> >>>> feedline? Sure, it would be better to know what the Resistance and
> >>>> reactance are. But, SWR will give you some idea as to where you are
> at. I
> >>>> think right now, you don't really know what your ground truth is.
> Tell me
> >>>> the SWR at 1.8, 1.85, 1.9, etc.
> >>>>
> >>>> 73 charlie, k1xx
> >>>>
> >>>>
> >>>>
> >>>> On 12/28/2018 9:30 PM, Todd Goins wrote:
> >>>>
> >>>> Hi Mike,
> >>>>
> >>>> Oh, I would totally believe that the air-wound choke is ineffective at
> >>>> 160m. It just happens to be what I had available to use when I rigged
> up
> >>>> the elevated radials in the cold rain yesterday. I figured I'd put it
> in
> >>>> line just in case.
> >>>>
> >>>> Thanks for the choke links, I will read the info on those sites.
> >>>>
> >>>> The air-wound choke is what I'm using when I'm feeding the antenna
> using
> >>>> the elevated radials. When I was testing using my buried radial field
> it is
> >>>> a different setup. There I have a DX Engineering radial plate that
> neatly
> >>>> ties everything (remote tuner, and DX Engineering Maxi-core Feedline
> >>>> Current Choke) together at the feed point.
> >>>>
> >>>> Thanks for the comments and info.
> >>>> 73,
> >>>> Todd - NR7RR
> >>>>
> >>>>
> >>>> On Fri, Dec 28, 2018 at 5:57 PM Mike Waters <mikewate@gmail.com> <
> mikewate@gmail.com> wrote:
> >>>>
> >>>>
> >>>> Hi Todd,
> >>>>
> >>>> I'll bet the farm (if I had one) that your air-core choke is
> ineffective.
> >>>> Take at look athttp://www.karinya.net/g3txq/chokes to see what I
> mean.
> >>>>
> >>>> A very, very good common mode choke is the one I have on mine,
> fromhttp://audiosystemsgroup.com/RFI-Ham.pdf. There is no better material
> >>>> written on this subject, either in print or on the Internet.
> >>>>
> >>>> 73, Mikewww.w0btu.com
> >>>>
> >>>> On Fri, Dec 28, 2018 at 7:34 PM Todd Goins <tgoins@gmail.com> <
> tgoins@gmail.com> wrote:
> >>>>
> >>>>
> >>>> ... I do have a common mode choke at (near) the feed point. It may or
> may
> >>>> not
> >>>> be effective at 160m. It does work on 10-80m. It is about 25' of RG-8
> coax
> >>>> wrapped around a 4" PVC pipe as a form. Perhaps not ideal... No RF
> noted
> >>>> in
> >>>> the shack.
> >>>>
> >>>> 73,
> >>>> Todd - NR7RR
> >>>>
> >>>>
> >>>> _________________
> >>>> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
> >>>>
> >>>>
> >>>>
> >>>>
> >>>
> > _________________
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
> >
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|