================= Begin forwarded message =================
From: cvanhoor@bcm2a02.attmail.com (cvanhoor)
To: cvanhoo@heartland.bradley.edu
Subject: KG9N/C6A trip review
I wanted to do a trip review and thank everyone who worked me
and put out the packet spots. Those sure can generate activity
are a lot of fun from the DX end!
The trip started at 1200 GMT Aug 3rd from Bloomington, Illinois
and arrived at Treasure Cay Bahamas 2050 GMT.(minus our luggage which we
recieved two days after we arrived back in Illinois) The trip proved to
exciting as the ride from Florida to Treasure Cay involved a beat up twin
engine plane with the radar working intermittently with thunderstorms
everywhere...Coming home we circled over the Atlantic for an hour as Miami
was closed due to a thunderstorm..How long can those little planes stay in
the
air anyway?.. ( Yes this was a commerical Flight.. an eight passenger
plane)..
The operation took place from the QTH of N4JQQ.(Steve is a great guy as
does a
nice job with his villa) Great beach, water, & fish. No crouds or TVI. We
had
the ocean to ourselves. The antenna was an R7 vertical (mounted 7 feet above
ground) and the radio was a Kenwood TS450. (This was Steve's radio as mine
was
hit by lightning the day before we left on the trip.. I'm still fixing
things
at home).. The location was great, about a minute walk from the beach,
looking
over seawater for Europe and the States.
All operations were early early morning and late night. I enjoyed the water
with the family during the day and the radio at night..I was beat when I got
home!... The first contact was with N8FU at 2150 gmt Aug3 on 14mhz cw. The
first South America was PY2OC. The first Europe was UR5LM. First Japan was
JR1TNI and the first pacific was VK9NS ..(long path on 20!) The final
QSO was with KC5FQX at 1138 GMT Aug 9.
The solar flux never got above 76 but fortunatly the A index stayed at 1.
I found propagation to be good even with the solar flux so low. I had one
sporadic E opening on 10 meters that went acrross the east coast as far west
as Colorado. This was fun as I was the first C6A for some novices and
even a couple of stations first DX. What Fun!! My best hour for phone
was 197 (20 meters) and on cw 181 (also 20 meters). I also enjoyed a nice JA
opening on 40 CW.
I spent time in the NA QSO party, the 10-10 international contest, and the
YO dx contest. (no wonder K4VX never let me operate I can not stay on task!)
I found the rates in the contest (NA QSO PARTY) to be slower than the rest
of
the week. I think a good operator good have produced a fine score in the NA
QSO party as 10 was open from down there and I was able to QSY stations from
10 meters to 40 meters for some quick mults and qso's. I was never able to
get
anyone to answer my cq on 10 though. Since I was not interested in S&Ping I
did not ask many stations to QSY. I could hear many stations on 80 but only
WW2Y, K4IQJ, AND K8SVT could hear me. I enjoyed the NA QSO party but
found my CW skills were not what they needed to be.
Here is a breakdown of my QSO's for the trip:
Phone CW
10 meters 163 5
12 meters 2 0
15 meters 3 22
20 meters 361 457
30 meters n/a 288
40 meters 1 719
80 meters 0 3
total 530 1491
Total QSO's...2021 (26% phone .. 74% cw)
Lessons learned:
1. Check the designation on your bags as the agent marks them.. Ours
we marked incorrectly by American and we never recieved our luggage
the entire trip.
2. Carry on everything you need..See number 1..
3. The only things you really need are radio equipment, dive equipment,
and swim suit..See number two..
4. Only fly Airways international if you have a good heart.
We all had a great time even without luggage and thanks again for working
me!
73 & DX
Chuck
KG9N
cvanhoo@heartland.bradley.edu
>From n2ic@longs.att.com (Steven M London +1 303 538 4763) Thu Aug 25 07:25:00
>1994
From: n2ic@longs.att.com (Steven M London +1 303 538 4763) (Steven M London +1
303 538 4763)
Subject: Open Wire Summary
Message-ID: <9408251825.AA16333@drmail.dr.att.com>
Many thanks to N3SL, VK5GN, K3NA, K4XU, W2VJN, WA6SDM, K7GM, N3RS, N6TR,
WA3NNA, L6LL, KD5PJ, K0SF, N5OP, WA8YVR and K8CH for their extremely helpful
comments on open wire line.
-----
Yes. Years ago, I did just that--hardline was too expensive (No CATV).
I had two runs one of about 200 ft, the other 300 ft. The shorter run fed a
10m monobander (later a 204BA), and the longer a pair of phased 40m
verticals. I used 4:1 baluns at each end. I was very pleased with the
results, and given the need, would do it again.
-----
You might want to talk to W9RE about open wire feeders ... he used to
feed several of his beams that way. As I recall, it was primarily for
economic reasons in his younger days when he was -- ahem -- short on
dough.
I never asked him about it, but I get the impression that it was a maintenance
headache and also presented a variety of "flakey" behavior problems that
had to do with proximity to towers, etc.
I will see if I can get him on here to comment about it.
-----
Hiya, Steve! Justthought I'd comment on your idea: I think it
sounds great. The 450 ohm ladder line stuff is quite good, with
losses comparable to what can be acheived my rollinh your own. Also,
with the spacing required for 450 ohm stuff, rolling your own is a
problem; most home-made stuff is around 600-800 ohms and baluns at
those transformations van get pretty lossy.
About the only problem I think you'd have is if wet snow gets
on the line; the stuff becomes lossy then and it's impedance will
undoubtedly change. Fortunately, we don't have lots of that here. If
it comes at a bad time, there's nothing to keep you from running a
broom along the line to clean it off!
-----
There was an excellent "how-to" article in Ham Radio Magazine in the early
80's (I'm guessing 1980 or 1981) where a W4 experimented with very long runs
of open wire. He had some dimens and techniques that he fell in favor with
over others. I would strongly recommend checking a Ham Radio Magazine
bibliography of those years (maybe even '79 and '82) and read the article.
Seems to me he even had 1000' lengths on 10 and 15 meters - with good
results! (noticebly better than coax or hardline). If I can find the
article, I will reply.
As a RF engineer, I would recommend two things: Run the lines horizontally
parallel, rather than vertically parallel to ground, since the line currents
will tend to unbalance if they're asymmetric to ground, which I'm assuming
is the nearest object. Also, tight corners are bad (discontinuity - large
bend radii being much preferred), and I would use a low characteristic
impedance (200 is better than 600; i.e., closely spaced lines will be much
less susceptible to loading or unbalancing by external objects and/or sag).
Toroids are getting so good these days that you can wind very high quality
broad-band matching transformers easily, but I would sweep them vs. freq to
insure no resonances or impedance deviations before stroking up power.
Also, avoid running the lines very close to gutters, towers etc. Again, I
believe closely spaced lines (low zo) are the way to go since it tends to
make the transmission line (which can be thought of two equal, yet opposing
currents changing sinusoidally in space & time; when these aren't equal, you
have an antenna, in fact, a beverege or travelling wave antenna) much less
vulnerable to surrounding objects. Sag may be important in 600 ohm lines (2
- 4 inches apart), whereas a 200 (~.5 inch) ohm line will not be as
sensitive to the same sag.
The same W4 proposed more exotic 4 and 6 wire lines which help control the
characteristic zo by spacing transmission line wires next to neutral (near
ground plane reference) wires. More work, but the concept works. This
system is analgous to microwave stripline.
By the way, I design microstrip antennas and transmission line systems for a
living. (I would not have responded if I felt I had nothing technical of
value to contribute).
Good luck. I am interested in your results, as I have 19 acres waiting to
be populated (space, but no time or money; takes all three to be loud these
days).
-----
A while back (last year??) there was a similiar thread on cq-contest. I
seem to recall the comments of the rf-gurus (W0UN, etc.) pointing out
some relatively unknown (at least to me) pitfalls of 2-wire ladder line.
Something about noise picked up from wind moving the wires or moisture.
Don't quote me here, I'm not 100% sure. I *do* recall, however, the
same rf-gurus pointing out the advantages of *4 wire* balanced line.
Sure enough, my old (1960 vintage) ARRL Antenna Handbook has a
description and formula for 4 wire line. It sez:
"In cross-section, the conductors of the four-wire line are at the
corners of a square, the spacings being of the same order as those used
in two-wire lines. The conductor at opposite corners of the square are
connected together to operate in parallel. This type of line has a
lower characteristic impedance than the simple two-wire type. Also,
because of the more symmetrical construction it is better balanced,
electrically, to ground and other objects that may be close to the line.
The spacers for a four-wire line may be disks of insulating material,
"X"-shaped members, etc."
According to the chart given, a 4-wire line of 200 ohms impedance can be
built from #14 wire spaced 2" apart, the distance being measured from
opposite corners of the "X".
Perhaps this type of line, using 4:1 baluns, may work better.
-----
Almost every shortwave broadcaster in the world uses open wire
feed for runs to the antennas. I just returned from a trip to
the VOA sites in SV, CN, A2 and S9. Miles of 4 wire 300 ohm line
going to huge curtain arrays pointed everywhere... fed with at
least 250kW.
When I lived in East Tennessee, a friend used ladder line to his
antennas. He lived in a real hole but owned the hill behind about
800 feet away. He supported it on trees and pressure treated 12'
2x4s using cheap ceramic electric fence standoffs. Don't run it
flat - twist it a few times between supports to maintain balance
and prevent flapping in the wind. Only maintenance problem was
occasional falling branches from ice/snow storms. The kind of
"snow" you get in TN is not available in CO. Rotator cable was a
major expense.
Low loss 9:1 baluns are a snap: 5 to 10 trifilar turns of #18ga
Teflon wire on a 3" ferrite core in a suitable enclosure. As you
said, its a low swr environment. Build two at a time and test
them back to back into a 50 ohm D/L.
How does ladderline compare to true open wire line? Very well. It is
within .1dB/100' of true 450ohm open wire at 30 MHz. And it certainly is
cheaper and easier than building your own. It is also easy to set up an
experiment on the ladder line - to test out the system before you commit
to it....
Regardless of where you get your hard-line, by the time you put
connectors on the ends, your investment is too high - unless you
already have cubic dollars and no children.
-----
I would be concerned about degrading the nulls of directional antennas in
the receive mode by using open wire line. I don't think the achievable real
world cancellation/shielding is nearly as good as coax.
-----
I tried using about 150 feet of 300 ohm open line - the old stuff with bare
copper wire and the little plastic insulators spaced every couple inches -
on 2 meters a few years back and it worked pretty good ... until it got wet.
Then the signals disappeared !!
Somewhere in the fine (invisible?) print I think it says that those super
low-loss figures for open line are only valid when the stuff is DRY.
-----
I think you are better off to make your own. K6NA has done this. You want
to get as few insulators as possible for there to be leakage. You can
find nice ceramic insulators that you can mount on top of your posts.
My 300 foot runs are 7/8 inch hardline which I was lucky enough to get free.
-----
Steve,
Unless you are talking VHF or UHF, there is no appreciable advantage to using
open wire lines. Hardline, for runs up to 500-600 feet will be well within
a dB of the open wire line up through 28 MHz and you will not have to worry
about the stuff getting iced-up or shorted by getting twisted in high winds.
-----
Many a year ago, I was one of the operators/station assembly people
at K8UDJ (now K8CH at ARRL). He had long runs and we used open wire
line. The only hassles were getting it out of the house and keeping the
ice off it. For you and the baluns the ice bit should be the only
problem - when it gets iced up it doesn't work so well. Other than that,
no losses to speak of and easy to install if you are in an area you don't
have to bury the stuff.
-----
When I was in the navy I was stationed at the San Francisco Communications
Station, located in Stockton,CA. I went the the transmitter site a couple
times at Davis, CA. They have open wire transmission lines all over the place
going to the various antennas. The power levels were 10 to 50 KW. The baluns
there looked like power company pole pigs. Saw pictures of commercial shortwave
broadcast stations, and they make big use of open wire. One even had an
open wire 'coax'. Seems like it is used by the big guys, so the idea definitly
is worth looking into.
-----
In the early 60s I put up a vee beam which was fed with KW 300 ohm
line and tuned for 80, 40 and 20. Every time it rained the loading
on my PL-172 amp would change enough to kick out the screen overload
relay and the presets for band changing were useless. Even after
waxing the line and twisting it the same would happen.
So I made up some open wire using #14 and plastic Polaroid film
spreaders left over from the Space Race. We were forever documenting
circuit operation with pictures of scope traces to bring to the
endless NASA design reviews so I had lots of spacers. The spacing
was about 3.5 inches I think. Anyway, this completely cured the
problem and there was no change in loading with rain or snow.
Fair Radio has some excellant spacers for open wire that are ceramic
and 2.5 x 0.5 inches. They would make a light weight line that
would be very low loss.
A few years ago I visited W1EVT, now KF1Z in the Boston area and
Clem had 12 towers on a hill top with driven wire arrays for all
bands and all directions. They were all fed with long runs of
open wire. Anyone who has ever been in pileups with Clem knows
how effective his arrays were.
-----
I made the measurements about ten years ago when I worked at Ten-Tec.
The comparison was made between 6" open wire line with ceramic spacers
every 10', Zo about 650 ohms, and 450 ohm ladder line. Frequency was
65Mhz, the upper limit of the HP-601. I used a Boonton rf voltmeter
as the detector. Johnson matchboxes were used at each end to make the
bal-un transition and transform back to 50 ohms. Identical parallel
250' runs of each were measured. The difference was 0.5dB favoring
the open wire, which translates to 0.092dB/100' difference at 30 MHz.
Poly does two things: it provides a support/insulation role and makes
the spreaders easily, and as a dielectric, it slightly reduces the
spacing necessary to get to 450 ohms. The higher the impedance, the
lower the loss. Windowing the line lowers the weight and the loss -
both the initial dielectric loss and the 'aging loss'.
Polypropylene is an outstanding rf dielectric provided it is not
exposed to uv radiation which causes it (and most other plastics) to
become brittle which decreases strength, causes surface cracks which
permit ingress of contaminants. The brown opaque fillers added to
prevent uv deterioration do increase the loss somewhat. Like many
other things in life, nothing is simple!
It is difficult to get good quality 450 ohm open wire line. It is hard
to keep it from twisting shorted on long horizontal runs. The
ladderline is inexpensive, easily obtainable at good quality. And it
won't short by twisting.
-----
Many thanks for your open wire information. Have been an open wire
fan for decades.
Just to be sure, is garden-variety poly ladder line (ie, approximately
1" ribbon line with "windows" cut out) really within 0.1 dB/100 ft
of "true" open wire line at 30 MHz? Seems hard to believe with all
that poly still there. Is that manufactures data or did someone
actually measure it?
-----
I have not used the manufactured stuff that looks like twinlead with
windows punched in it.
I did use ladder line for an incidental application one time. It was fine
for the intended purpose (feeding an extended dipole on multiple bands).
The main usage that I have made in the past is for long transmission line
runs. These were constructed out of 4 wire open wire line. 4-wire line
exhibits better balance characteristics and therefore (a) picks up less
atmospheric noise, (b) distorts antennas patterns less by picking up less
signal from unwanted directions, and (c) can be used with multiple runs closer
together than 2-wire line. My feeds were as follows, looking at the wire
end-on:
A B
B A
The runs were mounted on pressure treated posts up high enough to avoid
tangling with people, deer, etc. The wire were copperweld (I think #14).
Each post had an insulator with 4 holes that the wire passed FREELY through.
At one end of the run the wires were terminated into (in order): small
thimbles, short turnbuckle, and forged eyes mounted on a block of insulating
material. The opposite end of the block had another forged eyebolt and a
dacron braided rope over a marine block to a heavy counterweight. The
counterweight kept the line very straight and took care of temperature
expansion/contraction. The turnbuckles were used to initially balance the
tension in all four wires, a set and forget procedure. (You can use only 3
turnbuckles and run the 4th wire direct to the eyebolt, as you are only
setting the tension of the other 3 lines to equal that in the fourth. It
sound complicated but it really was a snap. I put small egg insulators a foot
or two before the turnbuckles to break the line and attached the balun at this
point.)
Because of the counterweight tension, there was no need for any spreaders
other than the post-mounted insulators. The post-mount insulators can be
easily made out of a sheet of insulating material with holes drilled at the
right places. I also used a holesaw to cut out the material between the
wires, in order to minimize any impedance bump from the insulators. Probably
a nit (as long as nothing metallic lays between the lines.)
Anyhow, the thing worked great. There is a reason why commercial
installations used a lot of this stuff (besides power-handling ability).
Oh, the wire spacing was about 2 inches on each side of the square and that
gave about 600 ohms, I think! (Check the handbook for the calculations.)
-----
I use 4 wire (200 ohm) line with 4:1 baluns at each end from shack to
base of tower. Works fine. We don't have the luxury of ex-cable company
hard line here!
Good article in Oct 1980 Ham Radio on the subject. If you have trouble
getting it I will photocopy and post - just let me have your address.
-----
>From Jay Kesterson K0GU x6826 <jayk@bits.fc.hp.com> Thu Aug 25 19:37:25 1994
From: Jay Kesterson K0GU x6826 <jayk@bits.fc.hp.com> (Jay Kesterson K0GU x6826)
Subject: Effects of palm trees
Message-ID: <9408251837.AA09803@bits.fc.hp.com>
> I am wondering if it was the palm trees that were more to blame than
> the aluminum wire. I have found that palm trees have a much greater
> effect on SWR when they are close to wire antennas than the redwoods
> and firs I am used to dealing with here.
> Peter AB6WM
This is a very good point for newbie DXpeditioners. My first trip to St.
Kitts I tried a inverted L and dipole for 80/160 strung near the top of
a bunch of short palm trees. Got on for the CQ160 SSB test and no one
could hear me! Moved the antennas out into the clear and they worked great.
Also if palm leaves come in contact with your antenna wire a considerable
light show can occur (with a KW).
73, Jay K0GU jayk@fc.hp.com
|