[TenTec] SLIGHTLY OT

[Rick - NJ0IP / DJ0IP]

Hi Art,

I read most of the suggestions.

Steve pointed out one very important point: you can improve 160m but
probably at the cost of performance on the other bands.

For that reason, I have always kept my 160m antenna separate from my other
antennas.

If I were in your situation, the first thing I would do is feed it as a "T"
antenna on 160m instead of openwire fed doublet.  You will need a quarter
wave counterpoise which (worst case) can be a piece of wire run along the
ground, zigzag.

If I were in your situation and wanted to optimize for 160m, I would use
linear loading but it sounds like Steve's idea of bending the ends won't
work due to space limitations.

There is another way.
You have to get another 60 to 80 ft. of wire into the antenna to make it
more civilized.
Add 30 to 40 feet per side and then somewhere near the middle of each side,
fold it back 180 degrees with about 6" to 10" of spacing, run it back
towards the middle for 10', then fold it 180 degrees and run it back towards
the end for 20', then fold it 180 degrees again, run back towards the middle
for 10' and with the final fold, run it to the end of the wire.

Gees, I guess a picture would show what I mean, much better than what I
wrote above.  I'll try a picture below.

This should solve your problem on 160m, but I don't know how it will work on
the higher bands.

Of course a better solution is simply to pack up and move to a house with
more yard!  ;-)

Let's see if I can draw you a picture.
The "O" or "OO" is an insulator, everything else is wire:


O-----------------OO----------------OO-----------------OO----------------O
                 |  |              feed               |  |  
           ------    ------        point        ------    ------
           |              |                     |              |
           ----------------                     ----------------

(I have not shown the spacers - just the wire and insulators)

Make the spacers for the linear loading out of PVC tubing or light wood.
We have some excellent stuff available here in Germany which would be
perfect for that.
If you are interested, I could check into buying it and sending it to you.

But before you go to all that trouble, just try feeding it as a T.
Connect the center and braid of the coax together and feed it like a
longwire (no balun at all), but don't forget the counterpoise.

You will get a good SWR for sure and probably have a much stronger signal
than with what you currently have.
This statement is based on experience using it, not modeling it.
Ran this many times in CQWW from several of my home QTH's.
It's not a great 160m antenna, but it works.

73
Rick


-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Art Trampler
Sent: Friday, April 08, 2011 7:14 PM
To: tentec at contesting.com
Subject: [TenTec] SLIGHTLY OT

It's on-topic, as I am using a 238B...
 
 
New antenna, 140' sloping dipole...apex about 50 to 55 feet, ends about 30
feet, so not quite an inverted vee,
 
Feedline: 600 ohm (or thereabouts) 14 gauge stranded, insulated wire using
73CNC spreaders, Guesstimated length: 110 feet. Feedline and antenna are
continuous pieces.
 
Tuner: 238B, followed by 10 feet of LMR600 to a 1:1 current balun from
Balun Designs (to get out of the shack).
 
On 160 meters, I wound up in Hi-Z "5" position to get a 1.8:1 match. Am I
looking at Hi-Z because the antenna length is about 1/4 wave? If so, would
it help so add 20 feet to each end, even if it went at nearly a right angle
to the antenna? Or is this really unimportant/not an issue as long as I get
a match?
 
Also, what recommendations do other owners have for additional capacitance
if necessary? I have not replaced the internal capacitors with the Russian
doorknobs but might at some point.
 
Interested in your thoughts. If the Pegasus S-Meter is at all accurate, I
was hearing Russians a full S-unit better on 20 meters last night with this
antenna than with my AV640 vertical. Japan is off the end, so the vertical
is better in that direction.
 
73,
Art
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