Being on the amateurish side of amateur, I wonder if I can get a little help
and advice regarding an antenna project I'm looking into. I am interested
in putting up a fixed, directional antenna for 30M - something more than the
two dipoles I currently have, and would like to focus on the Europe/ Middle
East path. What I am considering is a wire beam. My problem is the only
option I have for stringing one is a two or three element Inverted Vee. Can
anyone tell me if I am off-base on this one? Primarily, will the Inverted
Vee profile completely disrupt the radiation pattern and render it totally
unpredictable? Is there any value having parasitic elements configured in a
vee or will I lose all benefit of gain and FB? Any help or guidance would
be appreciated, especially since I haven't begun any preparations other than
having too much time over winter to ponder such things. I was thinking of
pointing it east/ northeast, but that is based on a radiation pattern
broadside to the driven element. I have tried a half-square but wasn't
pleased with the results even though I had a good SWR - it just seemed to
always result in weaker reports than either of my dipoles, but most of those
reports were stateside, and I understand that they would typically have a
low-angle take-off. A structural antenna is out of the question - I am
limited to wires only.
Thanks - John K0JJH
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of
towertalk-request@contesting.com
Sent: Wednesday, April 13, 2005 5:14 PM
To: towertalk@contesting.com
Subject: TowerTalk Digest, Vol 28, Issue 64
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When replying, please edit your Subject line so it is more specific
than "Re: Contents of TowerTalk digest..."
Today's Topics:
1. HDBX48 failure experience (Charlie Hicks)
2. Re: HDBX48 failure experience (bob finger)
3. Re: Rohn HDBX48 failure (Roger K8RI on Tower)
4. Re: Mosley PRO 37 (Dennis A. Homerick)
5. Re: Mosley PRO 37 (larryj@teleport.com)
6. Re: Rohn HDBX48 failure (Steve Maki)
7. hdbx48 failure (Jim Jarvis)
8. "Noisy" ground with a balanced antenna? (Bill VanAlstyne, W5WVO)
9. Re: "Noisy" ground with a balanced antenna? (Jim Lux)
----------------------------------------------------------------------
Message: 1
Date: Wed, 13 Apr 2005 15:03:03 -0500
From: "Charlie Hicks" <charlie@hickssystems.com>
Subject: [TowerTalk] HDBX48 failure experience
To: towertalk@contesting.com
Message-ID: <GFEBIMJNBNPBDJMKPKEIOEGCCEAA.charlie@hickssystems.com>
Content-Type: text/plain; charset="US-ASCII"
I just thought I'd chime in on this - back in the early 80's I had a
free-standing HDBX48 with a Hygain TH6 on it at about 18" above the top of
the tower and what I remember as a Ham-M rotator (not sure on that one). It
was out on a farmstead and pretty open to the wind from most directions.
Long story but I left it there when I moved. A couple years later I drove
by and the new owner hadn't done anything with it. The rotator had stripped
out the the beam was free-wheeling in the wind.
Another year later the owner called me and said the whole tower, beam and
all had come down in a wind storm. He said the winds were clocked at around
80 MPH in the area.
So, perhaps the combination of the beam spinning in the wind along with the
tower in the wind caused it to go down?
I forget what the wind load was on the TH6 - maybe 10 sq ft?
Charlie K0CKH
------------------------------
Message: 2
Date: Wed, 13 Apr 2005 16:22:09 -0400
From: bob finger <finger@goeaston.net>
Subject: Re: [TowerTalk] HDBX48 failure experience
To: towertalk@contesting.com
Message-ID: <425D7F71.70609@goeaston.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I just purchased a 22 year old HBDX 56. It needs cleaning and some cold
galvanizing but is in very good shape. This is surprising since it held
up a TH6 at its previous qth for all that time without any maintenance.
Rotor was mounted just inside the top section. I would never ever
consider a TH6 on top of an HBDX56. Some guys get lucky. I'm glad it
didn't kill anyone.
My plan is a long torque tube to the base and it will hold up only a
C3E fixed on EU. It'll probably last another 22 years, if I am so lucky
to be around that long. 73 bob de w9ge
Charlie Hicks wrote:
>I just thought I'd chime in on this - back in the early 80's I had a
>free-standing HDBX48 with a Hygain TH6 on it at about 18" above the top of
>the tower and what I remember as a Ham-M rotator (not sure on that one).
>
>
------------------------------
Message: 3
Date: Wed, 13 Apr 2005 16:35:27 -0400
From: "Roger K8RI on Tower" <k8ri-tower@charter.net>
Subject: Re: [TowerTalk] Rohn HDBX48 failure
To: <ve5ra@sasktel.net>, <towertalk@contesting.com>, "Chuck Sudds"
<chuck@dxham.net>
Message-ID: <006401c54068$55bd1a40$6700a8c0@roger2>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
<snip>
HDBX48 metal on one leg! This caused the tower to actually fold over at
the 6ft level, right where the new rotor plate was mounted! Had I mounted
right at ground level, there is a chance, I guess, that it just might have
survived ;)
One thing I forgot to add in a previous post about rotors mounted down in a
tower. When mounted "in the tower", but at the base there is no give to
take up the stress and that small area takes the entire brunt of the torque.
If the rotor has a mount on the concrete, or a seperate mount it removes the
stress from the tower.
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
As I said, thankfully there was no damage other than the total loss of the
tower and antennas. The rotor survived, as did the mast, except for the
top piece. I had alot of damage photos but can't seem to find them right
now but if I do, I will put them out on my web-site for viewing.
Chuck K?TVD
>Chuck. The devil is in the details. Please share with us the details of
>your loss. Was your HDBX48 sensibly guyed? Share how you had guyed the
>tower. Did the guys break or pull out first? Was the tower guyed at the
>top
>and also lower? What was the wind speed? Was it a hurricane or tornado?
>How long a mast did you use? How far above the apex of the tower was the
>KT34XA mounted? Did the mast collapse first? Was the HDBX48 mechanically
>sound?...i.e all cross braces in place and secured.
>
>Doug/VA5DX
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 4
Date: Wed, 13 Apr 2005 17:05:16 -0400
From: "Dennis A. Homerick" <DHomerick@neo.rr.com>
Subject: Re: [TowerTalk] Mosley PRO 37
To: "WD9DZV" <wd9dzv@gmail.com>, <towertalk@contesting.com>
Message-ID: <003901c5406c$80836eb0$6401a8c0@main>
Content-Type: text/plain; charset="iso-8859-1"
Tim:
Sorry I can't help with manual. FYI, I wouldn't send any money too
Mosley for a manual. I sent a check last fall for a Pro 96 manual. After
waiting 6 weeks and no manual I asked for a refund. Haven't seen a check
after several repeat calls and emails!
Dennis, w8nw
----- Original Message -----
From: "WD9DZV" <wd9dzv@gmail.com>
To: <towertalk@contesting.com>
Sent: Wednesday, April 13, 2005 3:15 PM
Subject: [TowerTalk] Mosley PRO 37
> I just picked up a new in the box Mosley PRO 37. Unfortunally, there
> was no instruction manual with it. Does any one have a manual they
> could copy for me?
>
> Tim, WD9DZV
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
------------------------------
Message: 5
Date: Wed, 13 Apr 2005 17:16:38 -0400
From: "larryj@teleport.com" <larryj@teleport.com>
Subject: Re: [TowerTalk] Mosley PRO 37
To: towertalk@contesting.com
Message-ID: <40800-220054313211638841@M2W053.mail2web.com>
Content-Type: text/plain; charset=iso-8859-1
I see that they're not listed as having a booth at Dayton again this year,
either. Wonder what's goins on?
LJ
Original Message:
-----------------
From: Dennis A. Homerick DHomerick@neo.rr.com
Date: Wed, 13 Apr 2005 17:05:16 -0400
To: wd9dzv@gmail.com, towertalk@contesting.com
Subject: Re: [TowerTalk] Mosley PRO 37
Tim:
Sorry I can't help with manual. FYI, I wouldn't send any money too
Mosley for a manual. I sent a check last fall for a Pro 96 manual. After
waiting 6 weeks and no manual I asked for a refund. Haven't seen a check
after several repeat calls and emails!
Dennis, w8nw
----- Original Message -----
From: "WD9DZV" <wd9dzv@gmail.com>
To: <towertalk@contesting.com>
Sent: Wednesday, April 13, 2005 3:15 PM
Subject: [TowerTalk] Mosley PRO 37
> I just picked up a new in the box Mosley PRO 37. Unfortunally, there
> was no instruction manual with it. Does any one have a manual they
> could copy for me?
>
> Tim, WD9DZV
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
--------------------------------------------------------------------
mail2web - Check your email from the web at
http://mail2web.com/ .
------------------------------
Message: 6
Date: Wed, 13 Apr 2005 17:34:59 -0400
From: Steve Maki <steve@oakcom.com>
Subject: Re: [TowerTalk] Rohn HDBX48 failure
To: towertalk <towertalk@contesting.com>
Message-ID: <425D9083.4000203@oakcom.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
K8RI wrote:
> One thing I forgot to add in a previous post about rotors mounted down in
a
> tower. When mounted "in the tower", but at the base there is no give to
> take up the stress and that small area takes the entire brunt of the
torque.
> If the rotor has a mount on the concrete, or a seperate mount it removes
the
> stress from the tower.
Actually, there's a lot of cushion provided by a long
mast.
I had an extended guyed 72' HDBX style tower in the 60s,
with the rotator a couple feet off the ground, rotating
a 4 el tri-band quad through 70' of 1-7/8" OD pipe. I
was amazed at the almost 45? twist in that mast in high
winds. It was ridiculous, really. I should have used
a 2-1/2" or 3" mast on that one.
Steve K8LX
------------------------------
Message: 7
Date: Wed, 13 Apr 2005 17:33:56 -0400
From: "Jim Jarvis" <jimjarvis@comcast.net>
Subject: [TowerTalk] hdbx48 failure
To: <towertalk@contesting.com>
Message-ID: <KFEELJAIGCMCCCAELGPIKEEKCNAA.jimjarvis@comcast.net>
Content-Type: text/plain; charset="iso-8859-1"
Clearly, sheer winds from downbursts at leading edge
of Tstorms can be catastrophic, and Chuck's tower was
overloaded. BUT...
If the guys had been connected using a triangular bracket,
such as Rohn uses for mounting their torque arms on 25g,
and if there had been torque arms, along with the torque
tube to the low-mounted rotor...it's possible the stick would
have survived.
As I reflect on the one hbdx48 I saw fail, it related to the
guys being looped around the legs. Compressed leg structure
and no resistance to torque loading crumpled the section.
Ignoring, for the moment, the prime maxim of "following the
mfr instructions", I think this tower is viable for moderate
arrays, if the torque load is moved off the upper sections.
It STILL won't tolerate 20 sq. ft. in 100mph winds, without
guying...and only maybe then, if it's engineered.
(but PLEASE don't put 'em up next to a bloody powerline!)
n2ea
jimjarvis@ieee.org
------------------------------
Message: 8
Date: Wed, 13 Apr 2005 15:35:16 -0600
From: "Bill VanAlstyne, W5WVO" <w5wvo@cybermesa.net>
Subject: [TowerTalk] "Noisy" ground with a balanced antenna?
To: "_Mailing List Tower-Talk" <towertalk@contesting.com>
Message-ID: <000d01c54070$af357c40$0400a8c0@billscomputer>
Content-Type: text/plain; charset="iso-8859-1"
I've read in a couple places lately -- maybe in ads, not sure -- that
creating an "effective RF ground" (whatever that would imply at the
wavelength in question) can reduce received noise in the antenna circuit,
even when an "RF ground" isn't necessary for antenna current return, such as
when driving a correctly-tuned balanced antenna. Is this true? I work a lot
of 6M SSB/CW, and man-made QRN is often the limiting factor on receiving
weak sigs. My 5-el homebrew yagi presents a virtually pure-resistive 50 ohms
load at 50.125, according to my 259B. Wouldn't expect any improvement on the
transmit side. But would my receive noise floor really drop if I put down a
counterpoise under my carpet near the rig? Or outside? If so, why? I don't
see it. Please enlighten me as to how antenna currents developed by noise
sources could be reduced with an "RF ground". Given that the antenna,
feedline, and radio are perfectly matched to each other at 50 ohms, where
would these currents be flowing, and how would an "RF ground" reduce them?
Bill / W5WVO
New Mexico / DM65
------------------------------
Message: 9
Date: Wed, 13 Apr 2005 15:12:57 -0700
From: Jim Lux <jimlux@earthlink.net>
Subject: Re: [TowerTalk] "Noisy" ground with a balanced antenna?
To: "Bill VanAlstyne, W5WVO" <w5wvo@cybermesa.net>, "_Mailing List
Tower-Talk" <towertalk@contesting.com>
Message-ID: <6.1.1.1.2.20050413150546.026cf3f0@mail.earthlink.net>
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 02:35 PM 4/13/2005, Bill VanAlstyne, W5WVO wrote:
>I've read in a couple places lately -- maybe in ads, not sure -- that
>creating an "effective RF ground" (whatever that would imply at the
>wavelength in question) can reduce received noise in the antenna circuit,
>even when an "RF ground" isn't necessary for antenna current return, such
as
>when driving a correctly-tuned balanced antenna. Is this true? I work a lot
>of 6M SSB/CW, and man-made QRN is often the limiting factor on receiving
>weak sigs. My 5-el homebrew yagi presents a virtually pure-resistive 50
ohms
>load at 50.125, according to my 259B. Wouldn't expect any improvement on
the
>transmit side. But would my receive noise floor really drop if I put down a
>counterpoise under my carpet near the rig? Or outside? If so, why? I don't
>see it. Please enlighten me as to how antenna currents developed by noise
>sources could be reduced with an "RF ground". Given that the antenna,
>feedline, and radio are perfectly matched to each other at 50 ohms, where
>would these currents be flowing, and how would an "RF ground" reduce them?
>
>Bill / W5WVO
>New Mexico / DM65
>_______________________________________________
I could see where creating a single point ground, or a big ground plane
under your shack, might reduce the possibility of ground loops (or wiring
loops in general) that could pick up local noise and conduct it into the
inside of your radio (i.e. on the power wires?)
Here's an experiment.. Put a dummy load on the receiver input (or at the
antenna feed point). Does the noise still exist? If so, it's not getting
in through the antenna, so it must be coming in on wires, cables,
radiation, etc. In such a case, changing the grounding system might help.
Fooling with a PCR1000 indoors running off a laptop, I've found all sorts
of interesting phenomena and noise sources. Switching which outlets
various wall warts are plugged into results in striking differences in
received noise (both on a whip at the PCR1000 and outside antennas,
although obviously, more so on the former) Clearly, the new breed of
switcher based wallwarts aren't the most quiet devices in the
world. Laptop displays also seem to be big noise emitters (maybe the
inverter for the fluorescent backlight?)
By the way, the noisiest RF device I have is one of those pods designed to
read and control the OBD-II diagnostic port in a car. No FCC sticker on it
(perhaps it fits in an exempt category.. clearly it's faster than 9kHz
clock rate?) but it radiates enough to disrupt FM radio reception in the
car, to say nothing of killing HF radio anywhere near it.
------------------------------
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End of TowerTalk Digest, Vol 28, Issue 64
*****************************************
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
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