[TenTec] Re: ~ 1/4 wave 160 doublet

[Jules]

Jim,
I haven't seen this mentioned yet.  How about putting inductors on each of
the legs of the doublet you have or an 80m trap on each end of the 80 meter
inverted V with wire (doesn't have to be high or straight even) from each
end of the traps to get it close to resonance on 160.
For DX on 160m, verticals (even short loaded ones) are hard to beat.  I've
used a minooka special (google it) in the old days with a lot of luck from
the Caribbean.
GL, 73, de Jules   K8JK
----- Original Message -----
From: "Jim Reid" <jimr.reid at verizon.net>
To: <tentec at contesting.com>; <topband at contesting.com>
Sent: Tuesday, October 21, 2003 6:35 PM
Subject: [TenTec] Re: ~ 1/4 wave 160 doublet


> Hi again from Kauai,
>
> Thank you for the many notes from both Ten Tec and
> Topband reflector users.  Both groups offer some excellent
> technical advice from great folks!!
>
> A summary of notes and my responses:
>
> 1.  Several said to put both wires of the ladder line together
> at the tuner... and feed the thing right there..... making it into a
> single T topped vertical .... with some ground radials or
> a counterpoise along underneath.  Use the single ended
> output of the Palstar AT4K tuner,  not the balanced output
> terminals.  This tuner I bought several years ago, and seems is
> no longer sold.
>
> My response:  this means only the ladder line feeder is now
> going to do the radiating.  It is a 100 foot length of 600 ohm
> (4 inch spaced) line.  Or,  about 0.19 wave length of a
> frequency of about 1830 kHz.  Unfortunately,  the line runs
> just four to five feet off the ground and along side two
> bedrooms of our home for about 35 feet or so (with several
> feet of excess line length folded around in the run)  then rises
> on up to the feed point of the doublet about 55 or so feet
> high.  So there is not much vertical portion to do much
> effective radiating,  with a lot probably coupling into the house,
> and trees and bushes through which the line passes beside
> the house.
>
> 2. Try hanging wire off the ends of your dipole to make it
> 1/3 wave on 160 I operate a 1/3 wave on 80 and it works fine.
>
> Response:
> That is certainly possible.  This approach would require
> adding some 27 feet of wire length at each end of the
> present doublet. Unfortunately,  I have no way to get the
> wire any higher at the ends,  so the added wire would
> just be wandering about tied off to some scrub bushes
> or low trees.
>
> I suppose what I will have in the end is  near vertical
> radiation on 160,  hi.
>
> 3.  Add enough wire between the present ends,
> some 270 feet long altogether,  to make a half wave loop.
>
> Response:
> This could also be done,  but the loop would be a long
> horizontal rectangle,  no where near square.  The added
> wire to close the loop could not be as high as the
> present inverted-V 80 meter doublet.
>
> 4.  And this thought:  If your feed line plus half the antenna is
> a quarter wavelength together you have  low impedance
> reflected to the tuner. And nearly resistive. Easy to tune. If your
> feed line plus half the antenna is a half wave you have a high
> impedance at the tuner, easy to tune with some tuners, again
> nearly resistive.
>
> Response:
> Well lets see,  at 1830 kHz feed ladder line is 100 feet,
> or about 0.19 waves,  and half of the 80 meter doublet is
> about 62.5 feet,  total 162.5 feet,  or 0.3 wave length
> total of feed plus half the doublet.
>
> So neither of the above length conditions now,  however,
> I could shorten the 100 feet of feed ladder to get down to
> a quarter wave over all on 160,  some 134 feet for 1/4 wave.
>
> Just outside having a look,  and certainly there is excess
> ladder line length,  seems a total feed plus 1/2 the doublet
> length to total the quarter wave length of 134 feet or so
> is possible.
>
> I like this idea as the first approach now;  most easily
> accomplished at this time.  All that seems needed to try
> this is to cut about 28 feet of length from the ladder line,
> brining it down to a 72 foot run.
>
> 5.  Other ideas suggested:
>
> 5.1 Set up an inverted L...
>
> Response:
> As my antenna height is very limited,  not sure the inverted
> L or feed ladder acting as a short vertical radiator is going
> to do me any good over the resulting short length,  near
> vertical incidence antenna that I can manage.
>
> 5.2 Put up a full sized 160 dipole, and make bends at
> various points to get it to fit the lot.  This zig zag method
> isn't as good as putting up a 160 antenna in a
> straight line. But it does work fairly well.
>
> Another possibility for sure and would not require ground
> radials or counterpoise as the vertical feed radiator or
> L does.
>
> Conclusions:
>
> Last time I was on 160 out here,  I mostly heard,  but
> didn't work,  a lot of fishing drift net beacons,  hi.  They
> must be all around these waters together with the long
> line fishers.  Probably with a "cloud warmer" low wire
> on 160 again,  I might not hear much more again,  but
> at least I could participate in 160 meter activity around
> the islands out here,  what there is of it.
>
> I will try Dr. Jerry's approach of the over all quarter wave
> length of ladder line plus half the doublet length and see
> what happens.  If I understand his comments about the
> line length plus half the doublet,  and a low Z at the tuner,
> I could safely use 1500 watts out,  and perhaps  be heard
> be folks outside Hawaii.....maybe.  Wonder if I could hear
> them back,  hi.
>
> Thanks again to all and 73,  Jim  KH7M
>
>
>
>
>
>
>
>
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