[TowerTalk] Coax for ground wire
Mike Short
mike.short at mchsi.com
Tue Oct 21 07:19:13 EDT 2008
Use it for your image plane, not your lightning grounding system, and you
will be fine. The #4 wire, etc from your tower to your SPG is the correct
thing to do.
-----Original Message-----
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Sent: Monday, October 20, 2008 9:50 PM
To: towertalk at contesting.com
Subject: TowerTalk Digest, Vol 70, Issue 51
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Today's Topics:
1. Re: 160m inv. ell tuning network (jim Jarvis)
2. Re: Detuning Booms ... (Tony Brock-Fisher)
3. sub-harmonics again! (K1TTT)
4. buxcomm OCF windom(buxbomb) (k2vi)
5. In my search for Tower installations (AD5VJ Bob)
6. Re: buxcomm OCF windom (WA6RKN)
7. 6M quads (Greg)
8. Using old coax for ground wire (Scott McClements)
9. Re: Using old coax for ground wire (Richards)
10. Re: Using old coax for ground wire (Scott McClements)
11. A Thank You Note (Richards)
----------------------------------------------------------------------
Message: 1
Date: Mon, 20 Oct 2008 12:54:13 -0400
From: jim Jarvis <jimjarvis at optonline.net>
Subject: Re: [TowerTalk] 160m inv. ell tuning network
To: towertalk at contesting.com, kd8cwp at arrl.net
Message-ID: <776CA421-0D8B-46DE-ACDC-EA0D0902C327 at optonline.net>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
Lennie,
A visit to the ARRL handbook, and/or antenna handbook is in order.
As others have observed, depending on its length the inv. ell. should
have a low
base impedance, and not require a matching network. A lot depends
on the
ground system, and surrounding objects, however.
It is NOT true that using a matching network will raise the base
impedance, and
minimize the need for a good ground. nonsense.
I won't do your research for you... but you should read the handbook
section dealing
with matching networks, and their characteristics.
And, to reiterate what someone said... wouldn't it be better to
define the problem, and
then produce the solution, than to take Viking's solution for a tank
circuit, and look for
a problem to apply it to? If you actually needed both an inductor
and a capacitor, the
odds of yours being the right value ... knowing how Murphy works...
is vanishingly small.
If you can make the Ell 133', and you put out a reasonable array of
radials, you should be
in the range 35-60 ohms, somewhere in the band, and you can tweak it
from there. As a hint,
it's best to make it a bit long, and simply fold back the excess, to
tune it where you want it.
>
> I am trying to build a parallel tuning network for a 160 Mtr.
> inverted L. I have a variable capacitor and a roller inductor which I
> wish to hook up to help tune the inv. l. The cap and inductor are
> both made by the Johnson Co. The cap is model # 154-2-3 and the
> inductor is number # 229-201.
>
> My problem is that being electronically challenged and very new to
> ham radio, I don't know how to hook the items up to make them work
> properly. They are from a Johnson Viking set and I am hoping that I
> can make them work to tune the inv. L.
>
> I really don't know which end is which or where the different wires
> should be attached. I've done several searches on the net but have
> been unable to find any info that will tell me what I need to
> know. Any information you can give me will be greatly appreciated.
>
> Thanks, Lennnie. KD8CWP
N2EA
Jim Jarvis, MBA
President - Executive Coach
The Morse Group, LLC
People-Process-Strategy: Achieving Results in a Changing World
www.themorsegroup.biz
coach at themorsegroup.biz
Read our latest newsletter. Go to: http://www.themorsegroup.net/
Newsletters.shtml
------------------------------
Message: 2
Date: Mon, 20 Oct 2008 16:41:49 -0400
From: "Tony Brock-Fisher" <barockteer at aol.com>
Subject: Re: [TowerTalk] Detuning Booms ...
To: <towertalk at contesting.com>
Message-ID: <6E7798A4AA5B4DAA82704165D343F437 at JIMINY>
Content-Type: text/plain; charset="iso-8859-1"
Well, I had really hoped to be able to share a success story about detuning
booms, but unfortunately all I can report is a 'result'...
Situation:
KT-36XA at 80 feet, 8 feet above a 40-2CD on a swinging gate mount. Both
antennas can rotate, independently. As I have reported here before, there is
a significant interaction where the SWR on the 40 rises to 2:1 when the boom
of the XA is parallel to the elements of the 40. (i.e. antennas aiming 90
degrees apart).
Experiment:
As part of a recent rebuild of the XA (let me know if you want details), I
added wires from the boom joint bolts back to the boom/mast plate area. I
tested this with a variable capacitor on the ground, and found that a 200pf
variable would resonate nicely at 7.150. I built the capacitor into a
weatherproof enclosure. The XA has subsequently been reinstalled, and today
I went up the tower to install the capacitor. While at the top, I was able
to use an Autek RF-1 to get a very nice series resonance with the capacitor
and the boom of about 9 ohms minimum (a la W8JI references). I removed the
RF-1 and connected the capacitor in parallel with the boom wires.
Result:
No discernable difference in SWR behavior. I had hoped this would break up
the resonance enough to allow the 40 to think the XA was not there.
Obviously I missed something.
73,
Tony, K1KP
------------------------------
Message: 3
Date: Mon, 20 Oct 2008 23:41:15 +0000
From: "K1TTT" <K1TTT at ARRL.NET>
Subject: [TowerTalk] sub-harmonics again!
To: "reflector cq-contest" <CQ-Contest at Contesting.COM>, "reflector
-tower" <towertalk at contesting.com>, "YCCC" <yccc at yccc.org>
Message-ID: <68D6A02949364D1E85F1215990F9DA87 at k1tttibm>
Content-Type: text/plain; charset=us-ascii
I went through one round of this witch hunt a couple years ago and figured
it was a rare problem. But now its back again and even uglier than before.
And I just had a random chat with someone on 2m up here who has gone through
a similar problem, so I'm starting to think it may be more common than I
first thought.
What I am seeing is when I transmit on 20m something generates a subharmonic
at 1/2 and sometimes now 1/4 and occasionally 1/8 of the 20m frequency.
These are usually very clean signals, though sometimes at high power or very
low power they do become intermittent and raspy. There is one other odd
thing this does, transmitting on 20m not only generates the 40m subharmonic,
but it then mixes with it and makes a 15m 3/2's harmonic... that is actually
where this chase started for me both times since that one is broader and
happens during peak run time on 20m!
When I went through this before I spent weeks trying to chase it out of the
shack. I swapped amps, radios, filters, tested into dummy loads, just about
everything before I was finally convinced it had to be outside and was not
just a radio or amp problem. Then I had to play around with coax and diodes
until I finally figured out how such a thing could be done without active
components. The key is a diode connected to something near a 1/2 wave
length on the lower frequency band. Basically when the diode conducts on
one peak a pulse goes down the 1/2 wave line, reflects back, and arrives
just in time to prevent the diode from conducting on the next cycle. An
example with 2 diodes is at:
http://www.k1ttt.net/subharmonics/subharmonic_files/subharmonic_frames.htm
I also did this with just a single diode... note the frequency used was
determined by the random length of coax I grabbed. The diode action gives
it a distinctive characteristic which is a sharp turnon threshold. As the
tx power is increased there won't be any subharmonic until a critical
voltage is reached when the diode turns on, then it quickly generates a
strong subharmonic.
What I finally found the last time was 2 pieces of jacketed hardline that
were not directly grounded to the tower at the top. Adding a hose clamp to
pull the connector shell against the tower leg killed that one, but not
until almost 2 years after I started hunting it.
That one usually needed well over 100w, usually near 1kw to get started,
this one I can do reliably with 25-50w on the top 20m antenna when pointing
it south. So far I have cleaned up and grounded more stuff in the last
couple weeks than I have done in years here. You can read all about it if
you want in the last couple weeks on my maintenance blog.
http://wiki.k1ttt.net/2008%20Maintenance%20and%20Upgrade%20Blog.ashx
I would be interested in hearing from others who have noticed this type of
interference to get some idea of how common it really is. I have a feeling
its more common that I once thought, just that you don't notice it unless
you are running 2 radios on the right bands.
I would also REALLY be interested in anyone who has some systematic way to
track it down. I have been up and down towers more these last couple weeks
than I have in years and still have no idea where it really may be. With
cables and antennas all around it seems to be everywhere, just about any
cable seems to have some hint of it.
David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
------------------------------
Message: 4
Date: Mon, 20 Oct 2008 21:05:40 -0400
From: "k2vi" <k2vi at cox.net>
Subject: [TowerTalk] buxcomm OCF windom(buxbomb)
To: <TowerTalk at contesting.com>
Message-ID: <009701c93319$22d3e1c0$6700a8c0 at your22ca86d5c4>
Content-Type: text/plain; charset="iso-8859-1"
this one has a 4:1 balun, off center fed dipole. I heard that the buxcomm
balun gets smoked at 600 watts. the balun states max power 1500w pep. So now
im wondering if i should put it up or just make a 80m loop or 40/80 fan
dipole. Any experience with buxcomm balun failure. I had this on in the
closet for a year now. Maybe i should put it on ebay.
tony k2vi
------------------------------
Message: 5
Date: Mon, 20 Oct 2008 20:31:47 -0500
From: "AD5VJ Bob" <rtnmi at sbcglobal.net>
Subject: [TowerTalk] In my search for Tower installations
To: <towertalk at contesting.com>
Message-ID: <009c01c9331c$c96685d0$6401a8c0 at RAD9FBHB71>
Content-Type: text/plain; charset="us-ascii"
In my search for tower/antenna installation projects (with your help) I have
come across many along with the videos I am studying
about various installations. The larger ones all have one thing in common,
no one man is involved, but many men of various
backgrounds.
But this one I had to share with the group.
Amazing project to me and a worthy future goal.
330 foot tower with
full-size 3 element for 160 meters
and 5 element for 80 meters
http://www.radioarkala.com/nbspStation/tabid/189/Default.aspx
73 fer nw es gud DX,
QSL VIA: LotW, BUR, e-QSL
Bob AD5VJ
http://www.ad5vj.com/
Old Calls WB5ZQU, WY5L/KH3, KE5CTY, N5IET
------------------------------
Message: 6
Date: Mon, 20 Oct 2008 19:46:19 -0700
From: "WA6RKN" <WA6RKN at ARRL.net>
Subject: Re: [TowerTalk] buxcomm OCF windom
To: "Tower Talk" <towertalk at contesting.com>
Message-ID: <01e901c93327$34f0d7b0$cd01a8c0 at main>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
I have run a Buxcomm, 6-80m Windom, for several years now. I also run an 14
year old Ameritron 811H.
I did, in fact, smoke the balun that came with the BuxComm Windom. I was
really annoyed as it was supposed to handle full legal limit, and the 811H
is far from legal limit. (800 watts CW max!)
I ended up putting a Black Diamond 4:1 current balun in the system and have
had no problems with it.
Joe Wolfe
WA6RKN
----- Original Message -----
From: "k2vi" <k2vi at cox.net>
Subject: [TowerTalk] buxcomm OCF windom(buxbomb)
> this one has a 4:1 balun, off center fed dipole. I heard that the buxcomm
> balun gets smoked at 600 watts. the balun states max power 1500w pep. So
> now im wondering if i should put it up or just make a 80m loop or 40/80
> fan dipole. Any experience with buxcomm balun failure. I had this on in
> the closet for a year now. Maybe i should put it on ebay.
------------------------------
Message: 7
Date: Mon, 20 Oct 2008 19:46:07 -0700
From: "Greg" <ab7r at cablespeed.com>
Subject: [TowerTalk] 6M quads
To: "Towertalk" <towertalk at contesting.com>
Message-ID: <003c01c93327$2b69e0b0$0302a8c0 at ab7rshack>
Content-Type: text/plain; charset="iso-8859-1"
Anyone out there have the directions for the 6M kit for a 2-el lightning
bolt quad?
Thanks
Greg
AB7R
------------------------------
Message: 8
Date: Mon, 20 Oct 2008 23:41:29 -0400
From: "Scott McClements" <kc2pih at gmail.com>
Subject: [TowerTalk] Using old coax for ground wire
To: "towertalk reflector" <towertalk at contesting.com>
Message-ID:
<dc722d260810202041yb5abf9v94fe6f5f21133a5b at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hey all - I am planning my grounding system for my new tower. I am
going to run multiple ground rods. I have a bunch of really old 9913
and RG-8U. What would be the best way to use this to connect ground
rods together (it will run below the surface between rods)? Strip off
the jacket and tie the braid and shield together? Just pull out the
#10 center conductor and use that? Or? I'll be cadwelding the wire
onto the rods, but I was up in the air on how to prepare it for use. I
almost threw it in the garbage this weekend then I came to my senses
on the price of copper and my impending need for ground wire. -Scott,
WU2X
------------------------------
Message: 9
Date: Tue, 21 Oct 2008 01:10:04 -0400
From: Richards <jruing at ameritech.net>
Subject: Re: [TowerTalk] Using old coax for ground wire
To: Scott McClements <kc2pih at gmail.com>
Cc: towertalk reflector <towertalk at contesting.com>
Message-ID: <48FD642C.7010609 at ameritech.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I don't think that is a good plan at all. That is not the right
tool for the job, and the braid on the coaxial stranded and far
too wimpy for the job. Why are you cutting corners on such
an important thing as grounding?
Many instructions for towers and antennas say not to
use braided or stranded wire, but only use thick, solid,
copper wire.
Example:
Rohn Products LLC R-AGK1G 1 Year Kit includes
3 - 8' copper ground rods, 3 ground rod clamps & 45'
No. 4 tinned copper ground wire. 30.00
So... number 4 gauge solid copper wire, and only $30.
That coax braid hardly matches up to this does it?
Please do your self a big favor and spend a penny to
get a high quality commercially manufactured grounding kit
for your tower. Your family's safety is way too important.
Use that old scrap wire for ground radials on a vertical antenna,
but not to ground for lightning or electrical safety.
Just my take.
Happy trails and 73. ---- Richards - K8JHR ----
=============================================
Scott McClements wrote:
> going to run multiple ground rods. I have a bunch of really old 9913
> and RG-8U. What would be the best way to use this to connect ground
> rods together
================================================
------------------------------
Message: 10
Date: Tue, 21 Oct 2008 01:45:33 -0400
From: "Scott McClements" <kc2pih at gmail.com>
Subject: Re: [TowerTalk] Using old coax for ground wire
To: Richards <jruing at ameritech.net>
Cc: towertalk reflector <towertalk at contesting.com>
Message-ID:
<dc722d260810202245i418ba902m22fde9097f0393e2 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
On Tue, Oct 21, 2008 at 1:10 AM, Richards <jruing at ameritech.net> wrote:
> Rohn Products LLC R-AGK1G 1 Year Kit includes
> 3 - 8' copper ground rods, 3 ground rod clamps & 45'
> No. 4 tinned copper ground wire. 30.00
>
> So... number 4 gauge solid copper wire, and only $30.
> That coax braid hardly matches up to this does it?
Look again - 30 is the weight, not the price. -Scott, WU2X
------------------------------
Message: 11
Date: Tue, 21 Oct 2008 01:50:16 -0400
From: Richards <jruing at ameritech.net>
Subject: [TowerTalk] A Thank You Note
To: Tower Talk <towertalk at contesting.com>
Message-ID: <48FD6D98.4030408 at ameritech.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Last Summer we had a thread discussing the merits of those coax
connector installation tools sold by DX-Engineering... you know... the
round brass dealies that help you push the connectors onto the coax.
I asked a serious question as to their real utility... and some kind soul
with arthritis politely said, well... yes, actually they are quite helpful.
Well... since then, I have been making patch cables and antenna cables
out of much heavier coax cable than I formerly used.... and well... I now
realize just how useful they really are ! Not that I doubted his answer,
but now I have experience to go along with his advice.
So -- I hereby RE-THANK the fellow who took a moment to so
kindly educate me. Now... I more than understand, ... I feel it.
Happy trails to all.
======== Richards - K8JHR ========
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