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1994-11-13
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Date: Mon, 24 Oct 94 04:30:15 PDT
From: Ham-Ant Mailing List and Newsgroup <ham-ant@ucsd.edu>
Errors-To: Ham-Ant-Errors@UCSD.Edu
Reply-To: Ham-Ant@UCSD.Edu
Precedence: List
Subject: Ham-Ant Digest V94 #354
To: Ham-Ant
Ham-Ant Digest Mon, 24 Oct 94 Volume 94 : Issue 354
Today's Topics:
### Advice needed for loss in BNC<->SO-239 connector
Beverage antennas (3 msgs)
Elnec Antenna Program
Send Replies or notes for publication to: <Ham-Ant@UCSD.Edu>
Send subscription requests to: <Ham-Ant-REQUEST@UCSD.Edu>
Problems you can't solve otherwise to brian@ucsd.edu.
Archives of past issues of the Ham-Ant Digest are available
(by FTP only) from UCSD.Edu in directory "mailarchives/ham-ant".
We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party. Your mileage may vary. So there.
----------------------------------------------------------------------
Date: 20 Oct 1994 16:12:52 GMT
From: s2202629@np.ac.sg (Teh Aik Wen)
Subject: ### Advice needed for loss in BNC<->SO-239 connector
I'm at present trying to homebrew an antenna. It's the first time I'm doing
it, and parts aren't exactly the easiest for me to find, especially since
I'm not very sure what I'm looking for. (Yes, I'm very new, and I don't have
a xceiver or anything for that matter).
Whats the antenna for? Thats a different story altogether.
Anyway, I've been trying to make this antenna featured in Sept'94 CQ.
(Anyone else doing it/has done it, care to email me?). I didn't read it
carefully enough, and bought a BNC connector instead of a SO-239 for the
antenna. Not difficult I thought, just go look for a 'single-hole,
rear-mount SO-239 socket'. But I didn't seem very successful in finding it.
What I did find however was a connector that was a BNC to SO-239.
I was wondering, how much 'losses' would I face if I went ahead and used the
BNC, followed by this connector? Reason why I want to do this is because I'm
having difficulity in finding the SO-239 (single hole, rear mount).
Just a note, the 'other side' of the SO-239 socket was supposed to be a
lenght of RG-58/U that is some 2" and then connected directly to the twin
lead (that makes up the antenna).
Thanks.
------------------------------
Date: 19 Oct 94 22:29:42
From: Dave.Headland@f725.n635.z3.fidonet.org (Dave Headland)
Subject: Beverage antennas
Has anyone come up with a convenient way of remotely varying the resistance
of the termination to earth from the far end of a beverage antenna, from the
receiver end? I've been playing with an idea of using photocells, controlled
by LEDs, but have come up with a problem of too much resistance in the
antenna wire.
The beverages I've been using varying from around 750 metres to around
2000 metres in length. Using twin-flex cable the resistance is roughly
45 ohms per 250 metres, so at 2000 metres you have roughly 360 ohms - too
much resistance for several (approx 5) LEDs to operate from a 12 volt
battery.
Resistance in antenna
approx 360 ohms.
o----------------/\/\/\/\/\/\/\----------------o-------o
| |
Receiver (& 12 << BEVERAGE ANTENNA >> LEDs Photocells
volt battery) | |
o----------------------------------------------o |
-----
---
-
Rather than use additional batteries to boost the voltage, I'm after a
circuit that could perhaps take advantage of the high resistance and
adjust the bias of a transistor (controlling the LEDs) at the terminated
end. The 12 volt battery doesn't necessarily have to be at the receiver.
Sooner or later I will be restricted to using single core cable for the
antenna, and will need to control the LEDs with a return circuit through
the ground back to the receiver. I am not sure what resistance this involves
but I suspect several hundred k-ohms, if not meg-ohms.
If anyone has overcome this problem I am interested to hear your comments.
I've tried radio controlled servos controlling potentiometers, but without
a great deal of success....
--
FidoNet: Dave Headland 3:635/725
Internet: Dave.Headland@f725.n635.z3.fidonet.org
------------------------------
Date: Sun, 23 Oct 1994 23:48:22 GMT
From: jeffrey@kahuna.tmc.edu (Jeffrey Herman)
Subject: Beverage antennas
Dave.Headland@f725.n635.z3.fidonet.org (Dave Headland) writes:
> The beverages I've been using varying from around 750 metres to around
> 2000 metres in length. Using twin-flex cable the resistance is roughly
What's their average height above ground, Dave?
.73W,
Jeff NH6IL
------------------------------
Date: 23 Oct 1994 23:50:01 -0400
From: jimkd0av@aol.com (JimKD0AV)
Subject: Beverage antennas
In article <321_9410221145@unique.pronet.com>,
Dave.Headland@f725.n635.z3.fidonet.org (Dave Headland) writes:
> The beverages I've been using varying from around 750 metres to around
>2000 metres in length.
Dave, you may want to consider shortening them as they become pretty
inefficient after 3 wave lengths...i.e., 480 meters on 160. 'That would
go along way in dropping ur resistance.
73, Jim KD0AV
------------------------------
Date: 22 Oct 1994 22:43:23 -0400
From: z004391b@bcfreenet.seflin.lib.fl.us (John W. Wilson)
Subject: Elnec Antenna Program
I have been using the ELNEC program since the Dayton Hamfest last
year. I found it to be a well written program and an excellent tool
for some antennae but has problems with Quads. The author admits
this drawback but the program is worth the money anyway. I also have
the ARRL MicroSmith program which accepts the ELNEC output. Together
these programs can analyze and ultimately provide design information
that would take time consuming experimentation otherwise.
73,
John, KN4HX
--
John W. Wilson
z004391b@bcfreenet.seflin.lib.fl.us
------------------------------
End of Ham-Ant Digest V94 #354
******************************