Two long radials on the ground is only one step above using just an
iron pipe in the ground. That should be common wisdom, like high
dipoles do better than very low dipoles, but alas, is not. Try two
elevated 1/8 wave radials with a series tuning inductor between the
center connection and the coax shield. This inductor can be varied to
help with SWR. Also be sure to use a common mode block on the coax at
the feed. You do NOT want the coax acting as a miscellaneous lossy
radial, which it will be otherwise. Ground the shield 25-50 feet from
the feed and do NOT ground the antenna directly underneath the feed
when you are on 160. Use the coax shield as your safety ground.
73, Guy.
On Thu, Nov 11, 2010 at 12:27 PM, Trent Fleming <trent.fleming@gmail.com> wrote:
> doing my best to improve my 160 capabilities on a small suburban lot. Only
> have G5RV up at this point, flat-topped, at about 30' Runs mostly N-S. I
> have added connectors to allow me to make it a "T" as follows:
>
> 1) Short stub of coax that connects to the SO-239 at the end of the G5's
> ladder line with PL-259. Other end has braid and center conductor twisted
> together. I feed that to the center conductor of another stub (from DX
> engineering)
> 2) The ground conductor of the DXe stub connects to a DX engineering radial
> plate. This is all at the base of the antenna.
> 3) I ran two long radials, one north and the other south, pretty much under
> the flat-top portion of the G5, each about 50' long
>
> I am already hearing better on 160, but my signal reports have been dismal.
> My MFJ-969 usually tunes the G5RV well across all bands, but tuning this "T"
> effort on 80 and 160 does not achieve a 1:1 SWR at all.
>
> Running 100w from Kenwood TS-690s.
>
> I KNOW this is not optimal, but trying to do the best I can at this stage.
> Only other real option is to run a low horizontal loop around my property .
> . .
>
> All comments welcome.
>
> Thanks
>
> Trent
> N4DTF
> (EM55 near Memphis, TN)
>
> On Sun, Nov 7, 2010 at 7:26 PM, Mike Waters W0BTU
> <mrscience65704@yahoo.com>wrote:
>
>> Hi Mark,
>>
>> N6LF recently found that the optimum radial length depends on how many
>> radials
>> you lay down. Check this out:
>>
>> http://www.w0btu.com/files/antenna/Optimum_no_of_radials_vs_radial_length.html
>>
>> 73,
>> Mike Waters
>> www.w0btu.com
>>
>>
>>
>>
>> ________________________________
>> From: Mark Lunday <mlunday@nc.rr.com>
>> To: Mark Lunday <mlunday@nc.rr.com>; topband@contesting.com
>> Sent: Sun, November 7, 2010 1:38:20 PM
>> Subject: Re: Topband: 160 meter current-fed T antenna, where did I go
>> wrong?
>>
>> Thanks very much to so many fellow hams who responded to my original post!
>> Nice to know the fraternity continues to help those with questions.
>>
>> This afternoon, a lovely fall day in North Carolina, I abandoned the
>> voltage
>> T and decided to "man up" and put down 6 x 120 foot radials for the 160
>> meter 1/4 wave inverted L which I had given up hoping for. I already have
>> 6
>> x 32 foot and 4 x 64 foot on the inverted L.
>>
>> RF coming back into the shack has been greatly reduced. Remote tuner
>> working just fine. Looks like I am headed in the right direction. So far
>> that makes 2 wavelengths of radial wire down. Probably need another
>> wavelength.
>>
>> Will listen tonight to see how things go. Anyone know where we are in the
>> "27 day solar rotation" which seems to affect 160 meters? Are we miday
>> through, nearing good conditions, nearing poor conditions, etc? Thanks
>>
>> Mark Lunday
>> WD4ELG
>>
>>
>>
>> _______________________________________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>>
>>
>>
>> _______________________________________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>
>
>
> --
> Trent Fleming
>
> www.trentfleming.com
>
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>
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> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|