Hi guys and gals,
Here is a nice article that Dale, W8ABZ sent me and I got permission to
upload it here at the HFpack group or other groups so that others may
benefit by it. This kit is made of 6 pieces of speaker, or whatever
multistranded insulated wire, each wire having a small socket on either end
similar to banana sockets and plugs. By connecting together at least 2
pieces at a time, you have the counterpoise you need for each band. So by
using variuos combinations of these 6 pieces you can cover all bands between
80 and 6 meters.
I built this nice kit and I tested it in all bands except for 80m. Sorry
guys I forgot to test 80 meters but it should work. My ATX, using my FT-817,
tuned straight away even on 15 meters where I have always had problems. I
also used it with my MP-1 and FT-817. I even used it with the 8 foot whip
that my RACAL 4031 has as standard accessory.
I used different colours of permanent markers to mark the white wires I
used, rather than using different colour plugs and sockets, as Dale suggests
in his nice article. I just could not find 6 different colour plugs here in
Greece. I only found blue ones, so I just used the markers to colour the
wires, well not all the length of the wire, just 1 inch near the connectors
at both ends.
I will upload the file and a picture that Dale sent me to the files section
of this group, so it is always there. You will be notified accordingly.
Enough talk. Here is the article:
------beggining of forwarded file-------------
From: "Dale E. Reed" <w8abz@...>
To: <articles@...>
Copies to: <sv1uy@...>, <dave@...>,
"Roy Hadden (KB8VJF)" <KB8VJF@...>,
"Jim & Elaine Kile" <starbird@...>
Subject: Article: Counterpoise kit for ATX antenna and FT-817
Date sent: Mon, 7 May 2001 22:22:40 -0400
QRP or Helpful Portable Hint (SAR?):
Counterpoise Kit for FT-817 with ATX-Walkabout Antenna
I am one of the many hams who has purchased the Yaesu FT-817 Backpack
Portable and found that it, indeed, brings the fun back into amateur radio.
I carry it with me in my computer bag daily to and from work. And my
notebook PC has RITTY, ChromaPix, DigiPan, Stream, AGWPE, WinAPRS and
several other ham applications loaded, so I'm pretty much always ready for
emergency or non-emergency (like demonstration) operations. And with a few
presentations (in Microsoft Powerpoint) always at the ready, I've managed to
get tapped to speak at a couple of club meetings while on business travel!
One of the items that completes the portable setup is the Watson
ATX-Walkabout antenna. I found out about this antenna after reading about
SV1UY's record-breaking pedestrian mobile QRP contact in the e-mail ARRL
Letter. (Yes, I know this is WorldRadio, but I am an ARRL member and read
the League's news, too!) I went to check out Demetre's web site
(), and there he mentioned this antenna.
It's
available at the Waters & Stanton PLC web site ().
The ATX-Walkabout looks like a little brother to the Outbacker series
of antennas. I've used the Outbacker Perth Plus and Outreach, both
excellent antennas. The ATX has a similar tap arrangement, but has a BNC
connector on the bottom instead of the 3/8-24 thread, and has a
telescoping upper part instead of a whip. The whole thing breaks down to
about a foot long and easily fits in the computer bag.
The manufacturer of this antenna recommends (for very good reason,
right Kurt?) that a counterpoise be attached to the ground lug of the
FT-817 for best operation. The length of the counterpoise wire, of course,
depends on the frequency, and a table of lengths vs bands is provided with
the
antenna.
Rather than carry all those lengths of wire, I decided that something
with a few wire segments with quick disconnects would roll up a lot
smaller. The trick was figuring out a small set of wire lengths that
would add to give all the lengths needed. I don't claim to have the
"mathematically optimal" set of lengths, but below is the design I
came up with.
These are the lengths of the wire segments and the color coding of the
quick-disconnect connectors:
Black connectors: 10"
Red connectors: 33"
Yellow connectors: 77"
Green connectors: 93"
Blue connectors: 120"
White connectors: 296"
...plus a very short wire with a spade lug to a connector, which I
leave on the back of the radio always ready.
For a given band, the length of the counterpoise = 180 feet / F (MHz).
(Yes, it's shorter than a quarter wave. See the explanation at the W&S web
site...) All combinations work out to the length recommended by the
manufacturer except as shown below.
Band Length Wire Segments vs Mfr. recommended
---------------------------------------------------------------------------
6m 43" Black + Red (as recommended)
10m 77" Yellow (as recommended)
12m 87" Black + Yellow (as recommended)
15m 103" Black + Green (as recommended)
17m 120" Blue (as recommended)
20m 153" Blue + Red (recommended = 154")
30m 213" Blue + Green (recommended = 216")
40m Phone 296" White (not specified)
40m CW 306" White + Black (recommended = 309")
75m G Phone 552" All except Yellow (not specified)
75m A/E Phone 586" All except Black and Red (not specified)
80m Data/Novice 596" All except Red (not specified)
80m CW 619" All except Black (recommended = 618")
(U.S. bandplan shown)
Notice how you never have more than two wire segments until you get to
75/80m. Of course, other combinations can be assembled for SWL or other
purposes. The whole package of wires and connectors rolls up to about the
size of a small donut or bagel.
I used Anderson Powerpole connectors because they are available with
the required shell colors, they are "genderless", but mostly because they
are very well engineered. They are popular with search-and-rescue
operations and local ARES groups, as I learned from the APRS SIG at
tapr.org -- repeatedly! (The Powerpole connectors seem to be a recurring
topic of heated debate on the SIG for some reason... :-)
Of course, I wouldn't suggest this design if I hadn't tried it. A 5-9
report from S57IIO on 15 meters the first weekend of May from the picnic
table in my backyard is typical.
There's only one other thing I want to add to this kit. I'd like to
get some small clips (or maybe hook/loop fastener straps in kind of an "H"
shape -- these could be used for rolling up the wires too!) to use for
locking
the connectors together so you don't lose most of the wire when you drop it
out
that hotel window!
Other quick disconnects can be used, but I strongly recommend the
Anderson Powerpole connectors for repeatably reliable connections and ease
of color coding. The counterpoise wires and a copy of the color chart
above,
tucked in a small zipper-locked plastic freezer bag, now have a permanent
place in my portable station. I hope you will find them useful too!
[Attached is a photo of the FT-817, the ATX antenna (two pieces, coil/tap
unit and separate telescoping whip), and the Counterpoise Kit.
Unfortunately I had no yellow Powerpole connector shells, so I used red ones
for the wire that should have yellow shells. Hey, it's just a prototype!
BTW, the green connectors are very dark green, and they look almost black in
the photo, but they are, in fact, green.]
Dale, W8ABZ
Cleveland Heights, Ohio USA
EN91
---------end of forwarded message-----------
====
73 de Demetre SV1UY
