On Sat, Dec 29, 2018 at 8:59 AM Grant Saviers <gran...@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 > Hello Grant, Thanks for the input. I've made a couple of modifications this morning. I can't make that choke today because I don't have the FT240-31 but I'll check out that design and look into ordering the parts. Sounds easy enough to build though. Yes, the BCB signal on the large wire is intense. When attempting to use it as a receiving antenna I have to run the attenuator and often dial out some RF Gain as well. Nasty stuff. I'll see about getting a BCB filter if for nothing else but to be able to use the antenna analyzer. I've looked at many designs I could build but they almost all have a cutoff freq above the 160m band. Not what I need... I raised the feedpoint to about 12' above ground surface and the radials are similarly elevated for their 130' length. The radial wire is insulated but it does use some (leafless) tree branches as supports. I have no way to add three more elevated 130' radials at this time. Good idea though. Raising the feedpoint did change the SWR readings at the rig. The 2:1 range is quite a bit narrower, which is an improvement, I guess. Here are the new readings. Indicated SWR at the 7300: 1.810 1.3:1 1.830 1.6:1 1.850 1.8:1 1.870 2.3:1 1.900 2.8:1 1.940 greater than 5:1 I'm looking forward to trying it out tonight in the Stew Perry. I still have the 43' L to fall back on if the performance has not improved. Thanks for the help. 73, Todd - NR7RR > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
