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 <[email protected]> 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 <[email protected]> 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 <[email protected]> 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 <[email protected]> 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 <[email protected]> < > [email protected]> 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 <[email protected]> < > [email protected]> 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
