PRB-1, DXers, Contesters and ARES
Sean E. Kutzko
tigger at prairienet.org
Wed Jan 31 13:16:04 EST 1996
N4ZR Wrote-
>I think everyone could come out winners in this. The ARES (or its
>equivalent in other countries) would get new resources to play its
more effectively. By participating, DXers and contesters
>could help blunt some of the criticism that their sub-culture now attracts.
>Participation would also help to counter arguments such as that in the
>Williams case above, and help protect our right to reasonable antenna
>installations. And finally, it could contribute to the policy arguments for
>continuing and expanding our frequency allocations.
>
>Comments?
I, too, read that editorial and took pause. I think this is an excellent
idea. Besides, if it's a toss-up between working that New One, a Top
Ten finish, or saving lives (or putting some non-ham's relatives at
ease about the condition of their loved ones), there really isn't much of
a decision.
73,
Sean
--
Sean Kutzko Amateur Radio: KF9PL
Urbana, IL DXCC: 305 wkd/302 cfmd
Photo available at: http://hobbes.ncsa.uiuc.edu/pictures.html
"Sure don't know what I'm going for...but I'm gonna go for it, for sure."
>From oo7 at astro.as.utexas.edu (Derek Wills) Wed Jan 31 21:23:06 1996
From: oo7 at astro.as.utexas.edu (Derek Wills) (Derek Wills)
Date: Wed, 31 Jan 1996 15:23:06 -0600
Subject: PRB-1 et al
Re: PRB-1, DXers, Contesters and ARES
>Besides, if it's a toss-up between working that New One, a Top
>Ten finish, or saving lives (or putting some non-ham's relatives
>at ease about the condition of their loved ones), there really
>isn't much of a decision.
He's right - it's not every day you get to work a New One!
Derek AA5BT, G3NMX
oo7 at astro.as.utexas.edu
>From Fred Hopengarten" <k1vr at k1vr.jjm.com Wed Jan 31 00:03:18 1996
From: Fred Hopengarten" <k1vr at k1vr.jjm.com (Fred Hopengarten)
Date: Tue, 30 Jan 1996 19:03:18 EST
Subject: Mac Contest Logging
Message-ID: <310eb1c8.k1vr at k1vr.jjm.com>
I've just received a letter from Radhames, HI3AB, whom I met
in Dayton a while back. He is looking for a logging program
for his Mac. As I am not a Mac user, I've ignored any
discussion on this topic which may have occurred in the
past, and I have nothing to write back to him. What shall I
tell him?
Is there a digest on this topic? KA9FOX: Have you got a
file on it? Thanks.
--
Fred Hopengarten K1VR
Six Willarch Road * Lincoln, MA 01773-5105
home + office telephone: 617/259-0088 (FAX on demand)
internet: k1vr at k1vr.jjm.com
"Big antennas, high in the sky, are better
than small ones, low."
>From Chad Kurszewski WE9V <kurscj at oampc12.csg.mot.com> Wed Jan 31 22:42:58 1996
From: Chad Kurszewski WE9V <kurscj at oampc12.csg.mot.com> (Chad Kurszewski WE9V)
Date: Wed, 31 Jan 1996 16:42:58 -0600
Subject: INV-L Match for 160M - Summary
Message-ID: <2.2.16.19960131164332.0aef87de at oampc12.csg.mot.com>
Well, here's the summary on how to match/feed your Inverted L for
160M.
The goal here was to bring as few components as necessary with me down
to the Carribean, but also to share what others have done to feed their
L.
Summary:
11 Used no match at all
4 Use just a ~2:1 UN-UN transformer (2:1 balun acceptable)
4 Use Cap and Coil (ala LC network) (ala Tuner)
2 Use shunt cap only
2 Use series cap only
2 Use series cap and balun
1 Use shunt and series cap.
Take the time to read the last response. It was written by John, K9UWA.
It has the most amount of explaination to it. That, along with some
antenna and Smith Chart knowledge, you will be able to explain the
vairous matching methods used.
Something very important that John says: "if you get a good match with
just COAX direct means ur losing a hellava lot into the ground".
It also depends upon what one thinks is a good match. Looking at the
antenna on an antenna modeling program, it appears that it is
approximately 25 ohms resistive, if cut to the proper length. This is
why I posted the original question on using a 2:1 UN-UN (balun).
Now, if you consider a 2:1 SWR okay, that's alright. But if you are
seeing closer to a 1:1 match, you might consider adding more radials
because you are losing a lot of power into the dirt. Either people
are happy with a 2:1 SWR, or those with better SWR with a direct feed
are experiencing a lot of ground losses.
Those that use a 2:1 UN-UN probably have their ground losses under
control and are seeing the proper 25 ohms, thus the need to step
that up by a factor of two.
Those using a series cap are simply bringing the reactance down to
zero for an antenna that is too long. If you have an efficient
ground, it would bring the Z to approximately 25 + j0. Those
that use a balun in addition to the series cap are doing so to
bring that 25 ohms back up to 50. Those that just use the series
cap are either experiencing a 2:1 SWR or have ground losses that
bring up the Z to 50 ohms.
Here's something interesting. Those that use a series cap....
they've stumbled onto something good here. If you start with an
antenna that is too long (0.335 wavelengths, to be exact) and then
tune it with a SHUNT cap (about 1730 pF for 1.840mhz), it will
match exactly to 50 ohms assuming minimal ground losses).
The only problem with this is that it is a higher-Q match and will
not have a huge bandwidth.
VE9AA hit it right on the head by saying that he uses a
5/16 wave (0.3125 wl) element. But then he throws me off by saying
he uses a 500-800pF SERIES cap. This would point again to a bit of
ground losses.
So, the lesson here is: If you have close to a 1:1 SWR with a direct
feed, you might want to consider adding a few more radials.
Many thanks to the numerous people who responded. This summary will
be archived on KA9FOX's WWW site for everyone's future reference.
Chad Kurszewski WE9V
chad_kurszewski at csg.mot.com
The original message:
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Can someone give me exact details of the match they used to feed
their Inverted L for 160?
We will be able to have the vertical part up about 40-50' and the
horizontal part starting there and going to about 20-25' high.
If the length is cut right, do I only need a 2:1 XFMR? Some air-wound
coil and a clip lead tap? I prefer not to bring down an antenna tuner.
How many (read: few) radials can I get away with and at what length?
So, what do you guys and gals use to match your Inv-L????
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And the replies:
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>From Bill, K5FUV <bkennamer at arrl.org>:
It is actually possible to get away with no matching network at all.
However, the length would be longer than a regular inverted L, possibly
as long as 5/8 wave.
Actually, the radio is happy with a good match, and the antenna works
just as well even if it's not quite resonant.
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>From Mark, K0EJ <SPECK at uansv3.Vanderbilt.Edu>:
I have a 65' up, 70'or so horizontal Inverted L which seems to play
well. I take a SO-239, put a fixed 500 pf cap across the shield and pin
and also put about 10' of RG-213 in parallel (gives you abt 700pf total
and 200pf of which is variable by trimming the RG213), attach abt 140'
of wire to the center and run it up and out. For easy radials (I use
on-ground vs elevated), I go to Radio Shack and get 1 or 2 of their 100'
lengths of 5-conductor rotor cable (abt $14 ea), solder the 5 wires
together to a lug, or cut into 50' lengths so you get 10 radials per 100'
chunk, tie them to a ground rod and the shield of the SO-239 and fan them
out on the ground. I plug in my feedline and trim the wire, then the
capacitor for best match. I get abt 90kHz below 2:1 and it seems to play.
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>From Jay, K0GU <jayk at fc.hp.com>:
> If the length is cut right, do I only need a 2:1 XFMR? Some air-wound
> coil and a clip lead tap? I prefer not to bring down an antenna tuner.
Probably. Model the thing on some antenna program. If its close to 25 ohms
a 2:1 UN-UN would do the trick. It maybe somewhat less that that though,
so a 2.2:1 UN-UN might be better. I think the L maybe more like 15 ohms
but that wouldn't be a real bad mismatch with a 2.2:1 UN-UN.
Another trick is to make the horizontal wire longer so that the thing is
now longer than a 1/4 wavelength. You can add wire till you bring the
R of the inverted L up to 50 ohms. Then tune the inductance out with a
series cap between the coax center conductor and the antenna. This will
cost you maybe a .5 db at low angle. But you will probably never miss it.
Protect the variable cap from salt spray! Or take along some doorknobs
in the vaule range you expect to need.
If your just trying to work US stations a inverted Vee at 40 feet with
the ends up 10 feet or so works well with a KW. From V4 I had a invee
@ 40' and 65'. Both time US stations told me what a great signal I had.
Also had success with a 60' invee from V3. Keep it away from large
concentrations of palm leaves.
The RX antenna will make or break your 160m operation.
For radials on the ground check out the chart in the ARRL Antenna Book
thats shows loss vs number/length of radials. If your L is near salt
water it will need less radials for the same results.
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>From Dan, W8CAR <pems_st_dk at noeca.ohio.gov>:
I use an inverted L on 160 now and it is 60 up and 110 over. I use a
series tuned network to tune it witha BIG cap and BIG coil. However you
could tune it with a series cap to tune out reactance and then use a
transformer to match it. I recommend one of the mutitapped ones of
W2FMI design that Amidon sells. That plus a cap will let you tune
anything.
I also used a 135 foot L once that was about the same dimensions you
are talking and tuned it with just a series cap. With this system you
can vary the length and cap to get a match.
If you want to engineer it before hand the only variable you need worry
about is ground condx. A roll of small diameter wire can give you good
radials. I use 3 eleveated radials on my L now and it works great (10ft
high) but they are tuned and you may not want to deal with that.
In any case an MFJ SWR thingie is a must to get it up and going.
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>From Steve, N4TQO <merchant at crl.com>:
Chad: here's info I got from WM2C just before going to VK9L -- it's
actually an article by noted TopBander K1ZM.
Total length 133', vertical portion approx. 40'.
Center conductor of coax feeds a coil 3" diameter, 6 tpi, 25-30 turns
total. The other side of the coil goes both to the antenna and to one
side of a 300 pf variable (3-4 KV spacing). The other side of the
capacitor goes to ground. Also connected to ground are 6 to 10 radials
60-133' long, and the shield side of the coax.
To tune: alternatively short out coil turns and tune variable for minimum
vswr.
Note: The coil and antenna end points and the capacitor are high rf
voltage points and must be insulated from ground.
I'm just writing this from the schematic in the article (August, 1990 --
The DX Magazine)
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>From Lars, SM3CVM <Lars.Aronsson at forv.mh.se>:
I use Inverted L for third season now, without any matching!
The vertical part should be so high as possible, bent the rest horizontal.
My is about 18 meter (54' ??) high. Total length is about 47 meter, I
think. Someone with Elnec can calculate the antenna to find the total
length. But make the antenna long enough so you can cut to find the
resonant FQ.
I feed my Inverted L on the ground without matching, no coil or anything
else, very close 1:1! I do not need any tuner.
Radials should be as many as possible, 1/4 wave. I use 20-25 radials (it
should be at least 50!), some shorter because lack of space in some
directions, with cu and ckickennet around the feedpoint. The most important
is the radials!
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>From Alan, K6XO <alan at greely.corp.es.com>:
I have an inverted L for 160 down here at the Rancho Costa Mucho,
and here is the configuration:
1/4 wavelength of insulated wire, 125 feet long.
40 foot tower.
The wire is strung from the base of the tower (about one foot
above the ground) up to an insulator which is tied on a rope
(by now, the wire is about 3 feet away from the top of the
tower). From the insulator, the wire goes horizontally for
about 85 feet to another insulator which is at the end of
another rope which goes over a tree limb at about 50 feet
above the ground. The tower has a 3 element monobander for
20 and another 3 element monobander for 15 above that.
Not too complicated. It kinda looks like this:
o_________________________o X
| X
| X
| X
| X
| X
\ X
| X
| X
\ X
| X
| X
\ X
| X
\X
X
The wire is fed with RG59U; the center conductor of the coax
is connected to the wire, and the shield of the coax is connected
to the tower which is grounded. The feedline is about 100 feet
long. No matching was required, and for some amazing reason that
I do not understand, it is very broad banded; that is, the SWR in
the shack is nearly 1:1 from 1800 clear up to 1900. At the top of
the band it is still under 2:1. I have been told that this should
not be, but it is. Dumb luck? Who knows? I have no radials, but
the tower is well grounded at the base with only one ground rod.
I should have more, they say. I have never tried radials, but you
have to believe that a radial or two or more would help. I have
worked about 8 or 9 European stations with this antenna and many
JAs, VK, KH6 and a few Caribbean stations. Amazing for such a
simple and inexpensive antenna. If you made the identical antenna
scaled down to 10 meters, it would be about 2 feet high, and the
horizontal section would be about 6 feet long .... .. Imagine
working DX on 10 meters with that... No wonder 160 is so tough.
Hope this helps. Good luck.
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>From Steve, WD8IXE <millersg at dmapub.dma.org>:
> Can someone give me exact details of the match they used to feed
> their Inverted L for 160?
<snip>
> How many (read: few) radials can I get away with and at what length?
Chad,
Here's the 160 matching arrangement for the 44' top-loaded vertical
we use at J6DX: it uses a single, air wound coil and the VSWR is
under 1.2:1 at resonance. The coil (from memory) is about 2" diameter
and probably 18 inches long. The turn spacing varies, there is a section
with fairly close spacing and another section with about 1/2 inch
turn spacing. Input impedance is fairly low so make sure the coil wire
is 16 AWG or larger. The coil is grounded at one end (radial system and
coax shield) and the vertical and coax (center conductor) are connected
to the coil at different positions. The vertical tap is between ground
and the coax tap.
coax tap 1 tap 2
(shield) to vert to coax
ground | |
radials | | (hot RF)
________ ___ ___ ___ _|_ ___ ___ ___ _|_ ___ ____
| \ / \ / \ / \ / \ / \ / \ / \ / \ / \
| X X X X X X X X X X
------ | | | | | | | | | | | | | | | | | | | |
/ / / | | | | | | | | | | | | | | | | | | | |
V V V V V V V V V V
By varying the tap positions of the vertical and coax, you can adjust
the resonance and VSWR of the antenna. We start with alligator clips
and find the proper tap points with an SWR analyzer. Once the tap points
are finalized, we solder them directly to the coil. Make sure the coil
is weatherproofed and well insulated (the unconnected end of the coil is
hot) from the ground/soil and nearby radial wires.
Now for a spiel on radials. Radials are very important especially for
short vertical antennas. Also, ground conductivity in J6 seems to be
noticably lower than W8. In '94 I took two sets of measurement on the
80m J6DX vertical using an Autek analyzer. The first measurement had a
radial system with 6 or 8 radials. The second measurement was with 40+
radials. After the trip, I determined efficiency was increased by 2.4 dB
due to the additional radials.
Since the radiation resistance of your 160 antenna will be much lower
than the 30 ohms (or so) of the 80m antenna, ground losses will be more
prominent. I STRONGLY recommend laying out lots of radials. Get a roll of
wire and go crazy. You might gain 4 or 5 dB on transmit. We use #22 magnet
wire, scraping the enamel off the end is the only (minor) inconvenience.
For your antenna, try for radial lengths between 50-100'. Shorter radials
will still help if you don't have enough room.
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>From Wes, N5WA <wes at prysm.net>:
Chad .... unless something really weird happens, you should be able to
easily match the Inverted-L with just the Pi-Net of your amp. It is an
unbalanced feed .... just hook the coax to it and go. If you insist on a
tuner out at the antenna, use a simple L-network. Matching at the antenna
won't do anything to help your signal, it would only make you feel better,
or, if the SWR is over 3:1 for some odd reason then it will make the amp
feel a little better.
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>From Bob, N5RP <perring at infocom.net>:
My inverted L is approx a 1/4 wave wire. It is made of two hanks of the
antenna wire that Radio Shack sells in (plus/minu) 65' lengths.
It starts out at the bottom of the tower (actually, around 14' above
the ground). It runs along the tower for the full length of ther tower
(75') and then goes out to the front of my yard for the horizontal shoot.
For the vertical run, I use aluminum tent poles that are hose clamped to
the tower. In the end of the tent poles, I screw in insulators in the
sweged down portion that would normally go into a tent grommet. I run
the wire thru those insulators.
The wire turns out to be supported around 3', or so, from the tower for
this vertical run.
If I were to feed it direct with coax, using no match,I get about
a 2:1 SWR.
When I put 2500 pf of capacitance (door knobs) in parallel with the
feed point, (connected right across the feed point) the SWR goes to 1:1!
The coax braid goes straight to bonded ground by simply clamping it
direct to the first tent pole.
No radials, but the tower is grounded to my swimming pool grid.
I am very pleased with my performance.
It always amazes me as to how well the simple piece of wire works !!
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>From Steve <sjarrett at mail.hq.faa.gov>:
I have always used direct feed, adjusting the radiator length until
a reasonable swr was obtained.
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>From Mike, VE9AA <wynder at brunswickmicro.nb.ca>:
I am fairly new to 160m, but have been foolin' wid hf antennas for
nearly 20 years. If I were you, I would use my inverted L as a 5/16
wave as opposed to a 1/4 wave...ie: 165' of vertical (es hz) + at the
very least 7 or 8 radials of 1/4 wave legnth, ie: 127' or so.
Hopefully you'll be a few hundred meters/yards from the water at most
so the # of radials significance will be reduced. I match all my 160m
antennas with simply a 500-800pf air variable cap inserted right at
the feedpoint (in series wid center conductor,radiator) and have had
great success. I worked 125+ countries my first Winter season alone!
1/2 of that season barefoot!!! I have tried dipoles, longwires, even
a quad, but have always came back to inverted L. (and compared 1/4
vs. 5/16) 5/16 better pattern it seems too. (for dx that is)
Anyway, for what it's worth. . . . . ve1pz uses same setup......
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>From Jack, K4MZW <k4mzw at mindspring.com>:
I'm using a 30-850mfd air-variable in an aluminum box borrowed from a
friedn in series with a 6" section of 1 1/4" PVC with about 30-35 turns
of #14 enameled wire in series with the cap. This I have tuned with my
MFJ Antenna Analizer and I am getting about 150-210 Khz of bandwidth at
or below 1.9:1 SWR.
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>From Pat, NZ4K <pcollins at freenet.columbus.oh.us>:
The impedence is going to be low < 20 Ohms. We use a trifilier wound
toroid transformer to match both our inv-L and 90' linear loaded tower.
Your best bet is to send a note to WW2Y (the god of inverted-L's) and he
can help you with what you need. Using his method you don't need any caps
or inductors.
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>From Larry, K7SV <lschim at mailstorm.dot.gov>:
Before putting up my tower, I had to remove the 40 meter double extended
zepp that I had been using on all bands, including 160 as a top loaded
vertical. During the fall following erection of the tower, I put a
couple of inverted L's up. The first one was a bazooka sort of affair
fed against a couple of 1/4 wave radials on the ground. I didn't feel
that it worked as well as the zepp did, so I tried raising the radials
above ground. I felt there was some improvement, but still not as good
as zepp. So I pulled the coaxial thing down and put up a plain old 1/4
wave inverted L with 70 feet vertical and the rest horizontal.
It worked about the same as the coaxial job. The point is, that with
that configuration vswr at resonance was about 1.8:1. I would guess
that your 2:1 balun would be correct. That's only based on that one
experience.
The other thing I would recommend is to elavate the radials if at all
possible. Get up just high enough so no one hangs themselves. You can
work an elavated radial against a ground mounted antenna. Just drop it
down at 45 degrees once you are a few feet from the L. I'm using two 1/4
wave radials made of insulated wire strung through trees at about the 7
foot level. I could only run them two directions, so that's what I did.
I figured out how to put another 40 meter extended zepp up again, and I
am convinced that it outperforms the L handily. In three years of
contesting and a little dxing I have something over a hundred countries
worked, including a VK6 on SSB. That's running one hundred watts.
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>From Peter, WW2Y <peter_hutter at maca.sarnoff.com>:
Try feeding the inverted L with direct feed with 50 ohm coax to see if
it matches with a reasonable swr ( 1.5 :1 or better). It all depends
on the radial ground system that you make. If you have more than 15
radials, you might need a 1.5:1 stepdown broadbanded transformer. You
could make it yourself, or purchase it from Amidon Associates. The
inverted L is an 1/4 wave type of course tuned for resonance to where
you want it tuned to be, eg. 1840. Try making it 134 feet to start,
cut it back to resonance.
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>From Ken, WM2C <ken.silverman at CCMAIL.AirTouch.COM>:
If you want to get fancy, play with coils etc. Every time I've used
an inverted-L on an expedition (or home), I've been able to tune it to
very low SWR just by trimming the length.
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>From George, WB5VZL <geoiii at bga.com>:
> We will be able to have the vertical part up about 40-50' and the
> horizontal part starting there and going to about 20-25' high.
I did this kind of thing at HR6A and I just feed it directly and
cut the length to match it.
> How many (read: few) radials can I get away with and at what length?
I just ran a few out as far as I could and tied a few to the fence that
went around the place. Seemed to work - My advice is to work on a
receive antenna - like a EWE or beverage 300+ ft if you can that will
gain you more qsos on 80 and 160 than anything else - the hard part is
hearing the states.
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>From Glenn, N3BDA <gdo at aloft.att.com>:
A friend of mine (N3MKZ) has an Inv-L with 4 elevated radials (~12 ft
high). The vertical wire goes up about 50 ft and then rides the
treetops the rest of the way (also ~50 ft). He directly feeds his
Inv-L with 50 ohm coax and has been doing great with it.
I plan to install a similar setup at my place. ON4UN recommends in
his book that you should put a current balun at the feedpoint. The
easiest and most practical balun is a bunch of toroids strung on the
end of the coax at the antenna feedpoint. I'll probably do that just
for good measure.
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>From Tony, K1KP <fisher at hp-and2.an.hp.com>:
I think the most important thing to bring is the balun - maybe
even something like a tapped unun that could give ratios in the
range of 1.5:1 to 3:1. I have used these things all over the place
and they can do wonders for balky antennas. In particular, I used
one on a 160 meter quarter wave sloper. You can always fix the
reactance by cutting/lengthening the wire. Then if you can
match the resistive portion, your home free. You can try
the unun forwards and backwards to find the right match.
A noise bridge would help too...
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>From Bob, KS9W <KS9W at aol.com>:
Well a couple weeks ago K9BG and I put one up in KP2 and last year we
put one up in J6 and both times the Inverted L worked great!!. All that
we used was a ground rod and 2 or 3 radials around 75 to 125 feet at
the feed point and between 125-135 feet of wire for the L element
depending on the match, and that's it. Both times we were able to
resonate the antenna at 1840 with an SWR of 1.5:1 or better. We found
that the ground rod is very important and if you try to add more radial
it just lowers the impedance and become's harder to match.
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>From Chuck, WA0ROI <cbrudtk at uswest.com>:
I use a 300pf tx mica cap at the base...in series....with my L. Also,
I have about 950' of radials down....think about 5 or 6 radials. Had
to keep away from the "important" 75m system radials. The 300pf was
found by experiment with a air variable.
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>From Steve, KM0L <km0l at tyrell.net>:
My Inv L on 160 is 65' up and 65' out, and is fed direct with 50 ohm
coax. I suppose this is a T match. Works well, but bandwidth is only
about 20 kc's and then a tuner is needed. Ant is made of stranded
copper wire. I used the elements of an old 80m dipole for 2 radials
(buried) an also attached my chain-link fence.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>From Brian, K3KO <ALSOPB at aol.com>:
I use a simple LC network. C in parallel on coax side and L in series
with the antenna. It matches my 30 ohms to the 50 ohm coax OK.
Capacity 2000-3000 pf, L about 5 or 6 two inch turns of #14. Tap for
the best SWR.
I use doorknob caps and run a KW into them with no problem. However
I have paralleled several to get to the capacity needed.
By the way, you need an impedance bridge to find resonace of your
inverted L. SWR is not the way to go. Its confused with the complex
component of impedance. First cut your antenna by minimum impedance
as a measure of resonance. Then design the LC network to transform it.
I have a small computer program to compute the components. Need only
to know impedance (resistive at resonance) and frequency desired.
I have about a dozen 1/4 wave radials and dozen 1/8 wave radials on
160M. It produces about the impedance one would expect for good ground.
Less might be OK. Depends upon ur ground conductivity, I guess.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>From Scott, K9MA <sellington at mail.ssec.wisc.edu>:
Perhaps someone with experience with just that kind of antenna can help
more, but I'd suggest a big coil and variable capacitor, so you can
make an L network. The capacitor will probably go on the feedline side.
You'll probably need around 2000 pF and 5 uH. The capacitor only
has to take about 400 V peak, but you may want some fixed capacitors
in parallel with a smaller variable.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>From Jeff, KU8E <jdclarke at freenet.columbus.oh.us>:
If you are near the ocean just run a wire into the water....
if not try 4 elevated radials ( about 10 feet of the ground)
I just put up and inverted L abt a week ago for CQWW 160. I
have 4 elevated radials and 2 other full size ones laying on
the ground. It works great . Been working EU every night ( and
I'm only running 100 watts !) GL and CU on 160 this weekend.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>From Dave, G4BUO <101332.232 at compuserve.com>:
I have had great success with my inverted L, 52ft vertical section and
about a 95ft 'horizontal' which slopes down to about 10ft. The matching
is a delta match, with a shunt 100pF capacitor from the antenna to ground
and a series variable capacitor from the antenna to the coax feed.
I have never measured the exact value needed for 1:1 SWR but it is a
500pF variable.
The ground here is wet clay and I get away with five 60ft radials much
of the time but this afternoon ready for the CQ 160 contest I have just
put out another three 130ft radials across neighbouring property. With
a low-ish vertical like this I have never wanted to try elevated radials
and haven't really got room for full-sized radials anyway. With just
the five radials I worked a lot of midwest and W6 stations when
conditions were good a couple of weeks ago.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>From John, K9UWA <k9uwa at mcimail.com>:
For your Inv. L....you need 40-50 radials small wire OK #26-28
about 100 feet long or so....nice if you have 135 feet.....and yes if
the inverted L is 50' high and balance is horizontal with end about 20-25'
up you need to take a 2/1 UN/UN xformer......if you get a good match with
just COAX direct means ur losing a hellava lot into the ground....Inv-L
with these dimemsions is 15 ohms if your ground system is a perfect
1/4 wave radius copper plate.....anything less than perfect ground raises
the impedence by that much ground loss=lousy signal.....if you can get
to about 10 ohms ground loss then thats not too bad...so 15 + 10 = 25
times 2/1 xfmr = 50 ohm coax.....this is exactly what I used at P40WA
Inverted L was about 40 feet away from 55' tower with 2L-40 + 4L-20 on it
QTH was AI6V/P49V's place.....my score is way over 1 mil....beleive me
it works.....good luck...hope to give you a point in the test
p.s. Maybe if you want to take something else along it would be a
nice 0-500 pf Cap...can then make the "L" a bit long and tune it
perfectly.....I took my MFJ-259 along...but it was useless as the AM
radio station less than 1/4 mile away put in stronger signals than the
little oscillator in the MFJ unit so I couldn't tell exactly what the
real impedance was.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>From Martin Durham" <wt1s at msn.com Wed Jan 31 23:26:42 1996
From: Martin Durham" <wt1s at msn.com (Martin Durham)
Date: Wed, 31 Jan 96 23:26:42 UT
Subject: No subject
Message-ID: <UPMAIL09.199601312346560871 at msn.com>
HELP
>From Fred Hopengarten" <k1vr at k1vr.jjm.com Wed Jan 31 23:27:49 1996
From: Fred Hopengarten" <k1vr at k1vr.jjm.com (Fred Hopengarten)
Date: Wed, 31 Jan 1996 18:27:49 EST
Subject: 40M 4 Square Advice Needed
Message-ID: <310ffaf7.k1vr at k1vr.jjm.com>
On Tue, 30 Jan 96 22:40:17 EST, "George McCrary" <geo at nando.net> wrote:
> As seen from my need for cheap verticals, I'm constructing a 40M 4
> square.
I have had a 40 meter 4 square since about 1982. It is
ground mounted, with 40 radials for each vertical. Each
radial is 40 feet long. It is fed with half inch hardline.
To EU, which is a high angle path from New England, the 4 sq
is down 15-20 dB from a 40-2CD at 90 feet, also fed with
half inch hardline.
To VK/JA/YB0 by long path in the afternoon, the 4 sq is
equal to the Yagi.
To JA/UA0 by short path in the morning, the 4 square is
almost equal to the Yagi, but not quite.
Your mileage may vary (YMMV), but if you are erecting this
antenna for contest purposes, you may want to buy and run
W1FM's propagation program, and then think hard about what
makes you loud in EU. That's where the Q's are.
Remember that Willie Sutton was once asked: "Why do you rob
banks?" He replied: "'Cause that's where the money is."
That is why you should think about the angle of propagation
to EU. A dipole at 72 feet may be better into EU than a 4
sq.
--
Fred Hopengarten K1VR
Six Willarch Road * Lincoln, MA 01773-5105
home + office telephone: 617/259-0088 (FAX on demand)
internet: k1vr at k1vr.jjm.com
"Big antennas, high in the sky, are better
than small ones, low."
>From MIKE,VE9AA & COREEN,WYNDER-PHOTO" <wynder at brunswickmicro.nb.ca Tue Jan 23 09:02:14 1996
From: MIKE,VE9AA & COREEN,WYNDER-PHOTO" <wynder at brunswickmicro.nb.ca (MIKE,VE9AA & COREEN,WYNDER-PHOTO)
Date: Tue, 23 Jan 1996 05:02:14 -0400
Subject: mla2500 help!
Message-ID: <09013436401116 at brunswickmicro.nb.ca>
Hi contest gang!
Anyone know the values of the two resistors
used in the parasitic chokes on top of the two
8875's in the 2500b? Cooked mine. . .
Contest tonight!
Mike
wynder at brunswickmicro.nb.ca
>From rlboyd at CapAccess.org (Rich L. Boyd) Mon Jul 1 02:55:41 1996
From: rlboyd at CapAccess.org (Rich L. Boyd) (Rich L. Boyd)
Date: Sun, 30 Jun 1996 21:55:41 -0400 (EDT)
Subject: KH6IJ callsign (!)
Message-ID: <Pine.SUN.3.91-FP.960630215353.26161C-100000 at cap1.capaccess.org>
Congratulations on obtaining your father's callsign, KH6IJ.
Many of us in the contest community fondly remember hearing that callsign
on the air over many, many years' time. We all hope you will consider
getting on during contests, finding a frequency to call CQ on (or tuning
up and down the band answering contest CQs) using that new call of
yours! We think your father would be proud.
73
Rich Boyd KE3Q (Bowie, Maryland, Washington, D.C. area)
>From rlboyd at CapAccess.org (Rich L. Boyd) Mon Jul 1 02:59:57 1996
From: rlboyd at CapAccess.org (Rich L. Boyd) (Rich L. Boyd)
Date: Sun, 30 Jun 1996 21:59:57 -0400 (EDT)
Subject: wenches
Message-ID: <Pine.SUN.3.91-FP.960630215920.26161F-100000 at cap1.capaccess.org>
Yes, some of us keep using the same wench forever even though sometimes
it should be replaced.
Rich Boyd KE3Q
>From Andrew at gi0nwg.demon.co.uk (Andrew Williamson) Mon Jul 1 00:25:07 1996
From: Andrew at gi0nwg.demon.co.uk (Andrew Williamson) (Andrew Williamson)
Date: Mon, 1 Jul 1996 00:25:07 +0100
Subject: IC765's, DVP boards and Heil mics
Message-ID: <fk6kXCATzw1xEw0z at gi0nwg.demon.co.uk>
Hi all,
I have a query from GI0KOW who is not on the internet, so I am
relaying it for Robert.
Robert has lately purchased an IC765, with which he would like to run
the DVP board in conjunction with CT for CQing. The DVP board worked
fine on his old TS930, but now after rewiring the lead to suit the ICOM,
the audio is very low. If an SM8 desk mic is plugged into the DVP again
the audio is low, but if the SM8 is plugged directly into the rig, it is
very strong. Is something really silly being missed here?. What is going
on?. Anyone else come across this problem before?
Also rumours have been heard that if a Heil boomset is connected to an
Icom radio, damage can occur unless a mod is performed on the radio. Has
anyone any idea what this mod is?. Or is the rumour just BS.
If anyone has used an IC765 with a DVP or Heil boomset (HC4 element) and
has figured out these problems, then please drop me a note directly.
73's
Andrew Williamson, GI0NWG (+G3OZF - U.K. team for WRTC)
E-mail : andrew at gi0nwg.demon.co.uk
One of the WestNet DX Gang.
Operations from EU006,007,103,106,124.
Please call us in the IOTA contest from EU-124 as GW6J.
>From n3rr at cais.cais.com (Bill Hider) Mon Jul 1 03:59:30 1996
From: n3rr at cais.cais.com (Bill Hider) (Bill Hider)
Date: Sun, 30 Jun 1996 22:59:30 -0400
Subject: IC765's, DVP boards and Heil mics
Message-ID: <199607010259.WAA00436 at cais.cais.com>
I used the Heil Boomset with my IC-761 for several years, no problems. I
now use it with the IC-781, no problems.
I never heard of any "Mod" for the Boomset for the ICOM radio!!
Only problem I heard of Boomset is with YAESU, not ICOM.
Bill, N3RR
At 12:25 AM 7/1/96 +0100, Andrew Williamson wrote:
>
>Hi all,
> I have a query from GI0KOW who is not on the internet, so I am
>relaying it for Robert.
>
>Robert has lately purchased an IC765, with which he would like to run
>the DVP board in conjunction with CT for CQing. The DVP board worked
>fine on his old TS930, but now after rewiring the lead to suit the ICOM,
>the audio is very low. If an SM8 desk mic is plugged into the DVP again
>the audio is low, but if the SM8 is plugged directly into the rig, it is
>very strong. Is something really silly being missed here?. What is going
>on?. Anyone else come across this problem before?
>
>Also rumours have been heard that if a Heil boomset is connected to an
>Icom radio, damage can occur unless a mod is performed on the radio. Has
>anyone any idea what this mod is?. Or is the rumour just BS.
>
>If anyone has used an IC765 with a DVP or Heil boomset (HC4 element) and
>has figured out these problems, then please drop me a note directly.
>
>73's
>
>Andrew Williamson, GI0NWG (+G3OZF - U.K. team for WRTC)
>E-mail : andrew at gi0nwg.demon.co.uk
>One of the WestNet DX Gang.
>Operations from EU006,007,103,106,124.
>Please call us in the IOTA contest from EU-124 as GW6J.
>
>From dave at egh.com (David Clemons) Mon Jul 1 13:30:03 1996
From: dave at egh.com (David Clemons) (David Clemons)
Date: Mon, 1 Jul 1996 08:30:03 -0400
Subject: Putting the fun back in contesting (long again)
Message-ID: <Pine.3.89.9607010828.A6960-0100000 at newman.egh.com>
I've had a somewhat encouraging response to my original message.
Some folks expressed a bit of surprise that I could lose code speed in a
5 month period of inactivity. Perhaps it makes more sense if I also
point out that I usually did not turn on the radio much at all during
those 5 months, so I had no CW at all. Of course, I didn't forget the
code - I just couldn't copy at fast speeds for very long. I suppose it's
endurance as much as anything. One person mentioned basketball. I also
played basketball a great deal in my early twenties - so much that my
new bride became a bit irritated and I felt compelled to stick around
the house long enough to say hello once in awhile. I also noticed
that a layoff of a month greatly reduced my endurance and timing. The
timing issue was especially painful as I was prone to catch passes off
the ends of my fingers until the timing came back. And the endurance
wasn't just noticed in my ability to run, but my shooting would be accurate
only for a short time until I got playing regularly again. Perhaps others
have not experienced this problem with CW or basketball, and if so I am happy
for you. For any of those who have experienced it, I still offer my original
ideas as a way to get you on the air and keep your abilities close to
their top levels.
However, the purpose for this followup message is just to add
another comment to the benefits I noticed with QRP operation as a teacher
of those things forgotten. I quickly noticed the effect of the grayline
with my QRP rig during CQ WPX CW. Of course I was already aware of the
enhanced propagation on the gray lines, but I often was sloppy about
looking in the right directions at the right time with higher power.
Although it was sometimes a bit more work, I often could break through
pileups when the grayline was favoring areas a couple time zones away.
Not so with the QRP rig! If I was there, I was able to work the
station. If not, I could still hear them but they did not hear me. So,
this was one more reminder to pay attention to details.
I also noticed enhanced propagation periods to some areas of the
US during field day, but these were not related to graylines. I have yet
to determine the mechanics of this phenomenon.
73, Dave Clemons K1VUT
>From robrk at fyi.net (Robert Morris) Mon Jul 1 17:12:50 1996
From: robrk at fyi.net (Robert Morris) (Robert Morris)
Date: Mon, 01 Jul 1996 09:12:50 -0700
Subject: DSP Boxes
References: <199606300100.SAA21348 at renaissance.cray.com>
Message-ID: <31D7F902.1B34 at fyi.net>
Maybe you got a bad one....Mine and others work fine for the $'s.
For the second rig (IC735) and minimum money, (on sale for $39)
the auto notch is great and the other funtions at least work.
I have yet to compare to the others to find what 10x dollars
will do.
>From jfunk at adams.net (jim funk) Mon Jul 1 15:19:02 1996
From: jfunk at adams.net (jim funk) (jim funk)
Date: Mon, 1 Jul 1996 09:19:02 -0500
Subject: squINT
Message-ID: <9607011419.AA06956 at golden.adams.net>
Hi All,
Can someone tell me how to find the results of the last squINT?
Can't seem to get subscribed to the right thing.
Please reply direct.
73, Jim N9JF
Jim Funk - Amateur Radio N9JF
Where the 160 antennas have Jersey "Cownterpoises"
"Cowpies happen. What you do with them determines whether you have a
renewable resource or an environmental hazard." -- Cownfucious
>From dieven at almaden.ibm.com (Dick Dievendorff) Mon Jul 1 16:16:07 1996
From: dieven at almaden.ibm.com (Dick Dievendorff) (Dick Dievendorff)
Date: Mon, 1 Jul 1996 08:16:07 -0700
Subject: WRTC rooms available
Message-ID: <9607010816.ZM20992 at penguin.almaden.ibm.com>
I have just inventoried the rooms available at the Motel 6 for the WRTC
period. Although they were "full" at one time, more than a dozen rooms
are now available. If you'd like a room in the middle of the action
for WRTC-96, and don't already have one, contact the Motel 6 in Belmont
California (directly, not through the national chain number) at (415)
591-1471. Not all their staff may be aware of the dozen rooms I freed
up on Sunday, June 30, so be persistent! If you want my help securing
a room I can give you a hand. I'll need the number in your party,
your arrival and departure dates, whether you want a smoking or non-smoking
room, whether you want one or two beds in the room. Credit card information
should be given to the hotel - I don't need or want that information.
73 de Dick, AA6MC
WRTC 96, Inc.
Housing & Transportation
dieven at almaden.ibm.com
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