[TowerTalk] Magic Length for 160-40 vertical?

[Herbert Schoenbohm]

I have suspended a T antenna from two 50' foot towers and a 50'drop 
wire...adjust the T to give a good match on 1.8 against ground. (A few 
radials will do.  Them with two additional drop wires on insulators off 
set on the T one cut to length for 3.5 and angled to the same feed 
point...and another for 40 meters....You can get some on 160-40 that 
preforms well with a modest ground radial system.  I made mine from THNN 
wire and even put in some CAT 5 Cables of various lengths.  Not the best 
RX antenna here but it works well on TX.



Herb, KV4FZ


On 11/4/2016 12:18 PM, Tom Osborne wrote:
> Hi Kirk
>
> To get the feel of a vertical, could you try shorting the feedline of the
> dipole together at the shack end and load it up as a top loaded vertical
> (with some radials of course)?
>
> Might be better than a really short vertical.  73
> Tom W7WHY
>
>
>
> On Thu, Nov 3, 2016 at 10:41 PM, Kirk Kleinschmidt via TowerTalk <
> towertalk at contesting.com> wrote:
>
>> Hi, gang,
>> I'm in a bit of a race against the clock (the winter clock), and I'm
>> trying to get a vertical up in the back yard that might be useful on
>> 160-40. (Never used a vertical before, but I wanna.)
>>
>> Assume that I have plenty of 50-foot radials or a 500-square-foot
>> galvanized ground screen (Rochester reportedly has excellent ground
>> conductivity).
>>
>> My other antenna (until Spring, when towers can go up) is a 102-foot
>> doublet fed with open-wire line, up about 40 feet (not exactly killer on
>> the low bands for DXing). The vertical doesn't have to be "the final
>> design," as it can be changed in the Spring, but it does have to be quick,
>> as my pre-winter window is closing soon.
>>
>> I am thinking about feeding it with an SGC or Icom autocoupler for ease of
>> multibanding, but I would consider making dedicated feeds for various bands
>> (100 W max for this first winter season).
>>
>> The main vertical element will be a 30-foot length of aluminum irrigation
>> pipe, either 3 inches or 6 inches in diameter. I'm not sure yet, as I don't
>> know which will be available to me. The 6-incher is 70 miles away, the
>> 3-incher is 120 miles, and I have to transport these pipes with a Ford
>> Focus and an 8-foot utility trailer (and lots of back roads).
>>
>> 30 feet is close to a quarter-wave on 40, of course, and I can add a
>> top-mounted loading coil. a top-mounted trap, a capacitance hat near 30
>> feet (like a 20 meter quad loop mounted parallel to the ground), or a
>> 22-foot fiberglass "whip" with heavy-gauge aluminum wire inside (or a
>> combination).
>> Without presenting "too-crazy" impedances on one band or another, is there
>> a "magic formula" for something like this, or is the frequency span just
>> too great?
>> As always, thanks,
>> --Kirk, NT0Z  Rochester, MN
>>
>> My book, "Stealth Amateur Radio," is now available from
>> www.stealthamateur.com and on the Amazon Kindle (soon)
>> _______________________________________________
>>
>>
>>
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