I have not had time to do a thorough investigation, but the 50 ohm beams
(nominal) I am feeding with 75 ohm double shielded coax, using only a choke
balun (no impedence transform) seem happier than they were with RG213...
Beats me - but I am not complaining.... I think the fussing to get an exact
match is much ado about nothing as the match is only an approximation as soon
as you change freq by 50kc, or so...
Denny
>From Lau, Zack, KH6CP" <zlau@arrl.org Mon Oct 9 14:15:00 1995
From: Lau, Zack, KH6CP" <zlau@arrl.org (Lau, Zack, KH6CP)
Subject: Matching thE beam
Message-ID: <30792021@arrl.org>
K1ZX wrote:
-----------------------
>Since I am starting from scratch on a new 20 meter CONTESTING yagi why
>wouldn't I want to design the gamma for it at 75 ohms. Since myy hardline
is
>75 ohms and I can use 75 ohm coax for the flexable section that allows
>rotation I can go this route and not need to worry about changing the
>impedance at two ends of the coax, right? I can have everything 75 ohms all
>the way from the beam down into the shack where, if it is necessary, I can
>use the series transformer approach or a 75:50 balun, right?
You might even be able to make things even easier by omitting
the balun. I'd be surprised if you couldn't get an amplifier that
would match 75 ohms. Different story of course for modern exciters.
On receive, you probably have a high enough noise level that
the change in source impedance would have a negligible effect.
A balun shouldn't be necessary, since both sides are typically
unbalanced. An impedance matching transformer would be
useful for running the exciter into the antenna.
Zack KH6CP/1
zlau@arrl.org
>From Larry Tyree <tree@cmicro.com> Mon Oct 9 14:22:03 1995
From: Larry Tyree <tree@cmicro.com> (Larry Tyree)
Subject: Cable clamps versus Philly
Message-ID: <199510091322.GAA14112@cascade.cmicro.com>
I have a third idea, and even a fourth (or is is forth?).
The forth idea is something I saw at W7NI's house, which is using
nyco-press (spelling?) with the wire rope stuff. This is really
cool looking and I think is superior to using cable clamps. It
is a little spendy and hard (but not impossible) to remove.
I use this to attach little 3 foot guy wires to my Rohn tourque arms
(yup, I use them on my 45). Then I switch to the high strength stuff
(the stuff you can't bend real easy) and use cable grips like the power
company does. I always figured they knew the right stuff to use. I
bought 100 grips at the place that sells them to small utility companies
for about $1 each (much cheaper than Texas Towers), and the cable seemed
to be free (it isn't hard to find as people don't like to use it).
A trick I learned helping AG7M put up his towers, is to use skill
saw with some sort of fiberglass blade to cut the cable. I made 10 foot
sections most of the time, the exception being near the ground. Then
another nyco-press with wire rope and 3 cable clamps at the turnbuckle.
The bottom of the turn buckle has another nyco-press to a short piece
of wire rope that goes to the anchor. So, each guy ends up with 2 sets of
3 cable clamps, which can be reached from the ground.
One tower did get done with all wire rope and nyco-press, but it was
pretty spendy, but it sure is nicer to deal with on the ground.
Tree N6TR
tree@cmicro.com
~v
A
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>From Chad Kurszewski" <kurscj@OAMPC12.csg.mot.com Mon Oct 9 14:51:41 1995
From: Chad Kurszewski" <kurscj@OAMPC12.csg.mot.com (Chad Kurszewski)
Subject: Beam Interaction - FYI
Message-ID: <9510090851.ZM8183@WE9V>
Hi all--
KS9K and I installed a new 40M beam this weekend and thought I might
share some info with everyone.
We currently have a homebrew, fullsize 3/3 stack at ~ 84/168' (26/52 m).
This is on a rotating AB-105 tower.
We wanted to put up a secondary antenna for picking up stations off the
side of the stack since the stack has >30dB F/Side and good F/B. So
we decided to go with one of those Cushcraft 402CDs.
Since all of the KS9K towers rotate, the only logical place to put the
secondary antenna was on the 40M tower, since we need to know the direction
of the tower. The secondary antenna is on a homebrew sidemount with +/-
90 degrees rotation. I determined that the best direction for the 2el
was 180 degrees out from the stack. This would allow us to cover the
sides and back of the stack. The 2el is at about 120' (36 m), about
40' (10 m) from the bottom 3el and 48' (16 m) from the top 3el.
So we hooked up the coax and went in the shack to check it out...not
even close to a 2:1 SWR. "What a piece of junk", I thought. Well,
we didn't check the SWR before putting it on the tower, but thought it
should resonate somewhere.
On a whim, I decided to rotate the 2el 90 degrees, such that the 2el
and the stack were at right angles to each other. WALLA! SWR that
is normal!!
40 foot (10 meter) (or 10 metre, depends where you are from) seperation
and a TON of interaction. I wonder how much it degrades the stack pattern.
I guess we will have to keep the 2el at right angles most of the time.
On a similar note, we are now back to a 4 stack on 20M and just wired up
the phase box. We can choose top only, bottom 3, or all 4. Looking at
the interaction (SWR) of these combinations, everything looks great.
The SWR of any of those combinations are great. The top antenna is on
a TIC ring and the SWR does NOT vary with rotation. The seperation is
42' (12.8 m), or about the same as on 40M (but double the frequency).
Hmmmm....what's up with that? Anyone got any ideas of what's happening
on 40M?
p.s. Sorry for the long message. I thought everyone deserved a break
from all the flames and might want to hear about some CONTEST antenna
stuff. :-)
--
Chad Kurszewski, WE9V e-mail: Chad_Kurszewski@csg.mot.com
Sultans of Shwing Loud is Cool....yeah, heh, heh, heh, LOUD IS COOL!!!
The Official Sultans Web Site: http://www.infoanalytic.com/ka9fox/sos
>From Keskinen Petri <oh3mep@proffa.cc.tut.fi> Mon Oct 9 14:58:04 1995
From: Keskinen Petri <oh3mep@proffa.cc.tut.fi> (Keskinen Petri)
Subject: LINEAR needed! any suggestions?
Message-ID: <199510091358.PAA04484@proffa.cc.tut.fi>
Hello, QRO men!
Couple of my friends has decided to buy new linears.
The do not have internet possibilities, so I promised
to ask Your comments.
The both have Yaesu FL-2100 and now they are looking
for bigger ones. Another of them has already a pair of
new 3cx800's so he is looking for something with those
tubes. Of cource he'd like to buy one without tubes, if
possible.
So what would be your idea of good linear with those
tubes? I do know at least Ten Tec TITAN (not sold anymore?),
Commander hf-2500, ALPHA ?? etc. Are there any others?
Perhaps some Amp Supply LK-800 (with 3*3cx800) or something
with just a pair of those?
Only Commander is available here, but local price is
terrible, how much does it cost in US?
Other one might have a pair of 3-500Z's (is it still
worth buying one with those?) at least it should be a rugged one
(not Tokyo Hy-Power HL2K or TL-922).
Does anyone have any experiencies with those new QRO 2000
linears which are advertised in CQ's? Is Amp Supply still
making lk-500 (or was it lk-550?)
Or perhaps that 91B is ok? What does it cost it US?
Is it available somewhere in Europe (perhaps in Bulgaria?)
Both should cover all HF-bands, 1.8 Mc to 28Mc if possible.
They will be used in contest and peditions, so it should
be OK to run those for full 48 hours, or even more.
I made too many questions, please give me any answer You
might have! Perhaps You should reply direct to me and i
could make a summary to the reflector if needed.
Mail to:
oh3mep@cc.tut.fi
or
pk75978@ee.tut.fi
TNX in advance!
Pete
oh3mep, oh0mep
* Life is too short for QRP! *
>From alan@ES.COM (Alan Brubaker) Mon Oct 9 15:36:54 1995
From: alan@ES.COM (Alan Brubaker) (Alan Brubaker)
Subject: CQP from Utah...
Message-ID: <199510091436.IAA21252@greely.corp.ES.COM>
K6XO/7 Single operator, unassisted, high power
SSB QSOs 417
CW QSOs 164
Total QSOs 581
Counties 58 = 76,908 Claimed Score
160 80 40 20 15 10
CW 9 24 45 68 18 0 164
SSB 6 75 218 114 4 0 417
3K short of my 1992 record. Life is tough in the skip zone, and the high band
propagation
just was not there. A brief 20 meter sporadic E opening on Saturday helped a
lot, but it
was very spotty, favoring Northern California. 40 SSB was the big band here,
with mostly
Sunday driver types giving me QSO number 1. Thanks to NG0X/6 in Colusa county
for calling
me on 40 for the sweep. First time since moving to Utah - I was always close,
but managed
to miss one or two counties in past years. This year receiving conditions were
very good
and I could hear many stations on the high bands who were unable to hear me
through their
QRM, but some dug down and pulled me out. Thanks to them.
Alan, K6XO
alan@es.com
>From Tim Totten, KJ4VH" <kj4vh@iglou.com Mon Oct 9 16:18:42 1995
From: Tim Totten, KJ4VH" <kj4vh@iglou.com (Tim Totten, KJ4VH)
Subject: Azimutal charts
Message-ID: <Pine.SOL.3.91.951009105846.13709A-100000@iglou2>
On Mon, 9 Oct 1995, Jose (CT1BOH) wrote:
> Hi there
> I wonder if annyone knows of a program that draws an azimutal chart center
> on a chosen QTH?
> And if theres one on an FTP site?
There's a terrific program called MicroCAM, written by Scott Loomer that
is now available as freeware (I think it's $1 for the disk) from some
U.S. govt agency. Maybe USGS? I use the program quite a bit at work,
and paid a good sum for it back when Scott was a private citizen living
in Hawaii. Scott has since taken a job with the govt, and part of the
deal was that his program came with him and is now available to the
public.
The program is basically a PC version of Computer Automated (Assisted?)
Mapping (CAM), and it does every kinda projection I've ever heard of.
It's not exactly simple (user friendly), but is quite powerful. Making a
custom azimuthal equidistant map is almost "beneath" the capabilities of
the program.
The version I have is 3.01. Given enough time, I could probably find the
ordering info when I return from Beijing, but I can't immediately put my
finger on it. The U.S. govt is certainly not promoting the software, but
it might be available on some FTP server. Maybe someone out there can
find it with Archie or Veronica, or otherwise knows how to order it.
Otherwise, I'll make an effort to dig it up when I get back to the office.
73,
Tim Totten, KJ4VH kj4vh@iglou.com | ". . . moderation in the pursuit
http://www.iglou.com/members/kj4vh.html | of justice is no virtue."
DX IS! | --Barry Goldwater, K7UGA
>From Jim Hollenback" <jholly@hposl62.cup.hp.com Mon Oct 9 16:34:28 1995
From: Jim Hollenback" <jholly@hposl62.cup.hp.com (Jim Hollenback)
Subject: RIT on the OMNI-VI
Message-ID: <9510090834.ZM27268@hpwsmjh1.cup.hp.com>
I forget who it was that was going to send a letter to Ten Tec about
the RIT and other things. Was there any response from Ten Tec?
73, Jim, WA6SDM
jholly@cup.hp.com
>From Stephen Lufcy <km0l@tyrell.net> Mon Oct 9 16:34:31 1995
From: Stephen Lufcy <km0l@tyrell.net> (Stephen Lufcy)
Subject: cqp score
Message-ID: <Pine.SUN.3.91.951009102754.7927A-100000@tyrell.net>
This message is in MIME format. The first part should be readable text,
while the remaining parts are likely unreadable without MIME-aware tools.
Send mail to mime@docserver.cac.washington.edu for more info.
--1913651334-1473985572-813252871=:7927
Content-Type: TEXT/PLAIN; charset=US-ASCII
Here's a minor score for CQP:
KM0L SO high power Mo
band 80 40 20 total
cw 7 46 85 138
ssb 45 45
183 qso's x 49 mult's = 24,696 claimed score
cu all in ss
de KM0L
--1913651334-1473985572-813252871=:7927--
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