[TowerTalk] R7 Traps

Sun Sep 6 14:08:28 PDT 2009

I just finished refurbishing my 1992 vintage R7 vertical.
The tips offered by web posting by PA0FRI  and EI7BA and VE6LB were very useful.
Should find them with a Google search.
Basically I replaced all the trap coil connecting screws with stainless, as most were corroded (copper/aluminum/steel = corrosion)
Coated all connections with anti-ox compound and new shrinkwrap.
Coated the top edge of the shrink wrap with liquid tape as I didn't have to good stuff with glue inside the shrink wrap.

Also. recoated the fibreglass insulator base with 2 part resin as described by PA0FRI (on his R5 )
and replaced the aluminum rivet with stainless steel bolts to get rid of any wobble.
Don't drill a bolt thru the aluminum tubing as it will eventually crack there with the continuous wind flexing.
You can feed a bolt up the inside of the tube by taping it to a long dowel or narrow piece of wood, until it lines up with the hole.  Tricky, but not hard to do.
Make sure the capacitors for each trap are water tight and not burned or deformed from high power op.  See Gerry, VE6LB's post on this.

Hope this helps,
73
Jeff, VE3FRX

________________________________
From: "towertalk-request at contesting.com" <towertalk-request at contesting.com>
To: towertalk at contesting.com
Sent: Saturday, September 5, 2009 3:00:37 PM
Subject: TowerTalk Digest, Vol 81, Issue 11

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Today's Topics:

   1. Re: finding aluminum tubing (Charlie Gallo)
   2. Re: NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY (D.W. Fearn)
   3. Re: finding aluminum tubing (Rob Atkinson)
   4. Re: NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY (K1TTT)
   5. R7 traps (Barry Fox)
   6. Re: R7 traps (AI4WM Bill)
   7. Re: CushCraft R7 Antenna Problem (AI4WM Bill)
   8. Telrex 6M624 antenna (Mike & Becca Krzystyniak)

----------------------------------------------------------------------

Message: 1
Date: Fri, 4 Sep 2009 20:19:37 -0400
From: Charlie Gallo <Charlie at TheGallos.com>
Subject: Re: [TowerTalk] finding aluminum tubing
To: "Joe Barnes" <n4jbk at bellsouth.net>
Cc: towertalk at contesting.com
Message-ID: <1895505755.20090904201937 at TheGallos.com>
Content-Type: text/plain; charset=us-ascii

On 9/4/2009 Joe Barnes wrote:

> Where oh where can I buy aluminum tubing to rebuild my telrex
> 6m624's? I have 3 bent /broke elements and apparently bin laden has
> all such tubing with him because no one knows where it is. any help would be appreciated. Joe N4JBK

Depending on how much you need, and sizes, there is always Yarde Metals

http://www.yarde.com/index.html

No affiliation except buying some 6061 from them

-- 
73 de KG2V

For the Children - RKBA!

My Website: http://www.thegallos.com
My Blog: http://kg2v.blogspot.com

Boycott shampoo!!! Demand REAL poo!

------------------------------

Message: 2
Date: Fri, 04 Sep 2009 20:40:08 -0400
From: "D.W. Fearn" <dwfearn at dwfearn.com>
Subject: Re: [TowerTalk] NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY
To: towertalk at contesting.com
Message-ID: <0KPH00H4A36YY392 at vms173017.mailsrvcs.net>
Content-Type: text/plain; charset=us-ascii; format=flowed

I was using RG-174 as a shielded lead in a product we build and 
experienced exactly the same problem as Larry describes. This was 
from a brand-new, very expensive roll of Belden RG-174. This was to 
the grid of a tube, so even a very high resistance had an effect. We 
have changed to a Teflon-insulated coax and that solved the problem.

Doug K3KW

>Date: Fri, 4 Sep 2009 06:55:15 -0400
>From: "Larry - K7SV" <k7sv at comcast.net>
>Subject: [TowerTalk] NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY
>To: <towertalk at contesting.com>
>
>Some of you may remember my posting about our experience with beverages
>using plastic boxes to house matching transformers. The black plastic boxes
>turned out to be conductive which obviously led to a lot of head scratching.
>
>Well, I've been working a small project using RG-174. I kept finding shorts
>after putting connectors on the ends. Nothing was making sense so it got to
>the point that I cut a foot long piece of the stuff, stripped back about an
>inch of the outer insulated jacket at both ends and pushed the shield away
>from the ends. I then took resistance measurements between the shield and
>the ends (didn't strip back the inner insulation, just stuck the meter probe
>in the end). So I'm still seeing resistance between the shield and the
>center conductor.
>
>On a whim I connected a meter probe to the inner "insulation" at both ends
>of the piece. Sure enough it was a conductive material. I picked up a couple
>hundred feet of this stuff from Mendelson's at Dayton a few years ago. As it
>turns out construction consists of an insulated black outer jacket, stranded
>copper shield, a black conductive material, a light opaque insulation and
>then the stranded copper inner conductor.
>
>My problem obviously existed anywhere that the inner black "insulated"
>material was touching the shield.
>
>This is the first time I've experienced something like this with RG-174.
>Actually as I think about it, the stuff must have really great isolation
>between the center conductor and the braid! I don't think this is typical
>RG-174!
>
>73 de Lar K7SV

------------------------------

Message: 3
Date: Fri, 4 Sep 2009 19:40:22 -0500
From: Rob Atkinson <ranchorobbo at gmail.com>
Subject: Re: [TowerTalk] finding aluminum tubing
To: towertalk at contesting.com
Message-ID:
    <d2bb1cb80909041740i7709d808qa67ad818a21871b1 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Jorge:

It's not my intent to get into a "testimonial war" so I'll freely
state that I have ordered from DX Engineering before, and the
cardboard box they used to ship my purchase in was of the best
quality.  The radial plate is a very nice radial plate too and still
works great with my 101 radials out in back.

I don't know who will pick up the phone at DXE when you call, but if
you call Penninger Radio a live mechanical engineer will answer the
phone during business hours (no machines and menus) and advise you on
a purchase based on his experience with forces on structures,
performing calculations on the spot as you give him your
specifications.   This is the only ham vendor I know of where after a
minute on the phone the guy is giving me the bending moment on a ten
foot mast at the top of a four foot quad mount for a 3 sq. foot wind
load at the top in a 70 mph wind and advising me on what o.d. and wall
thickness to use.

And I just purchased a 50 foot crank up aluminum mast from him in
which he did the whole design and put it all together for me and
guaranteed that if it didn't stay up he'd fix it until it does.  (It's
staying up FB).  But I'm sure everyone else has a fine product and
good luck with them.

73

Rob K5UJ

------------------------------

Message: 4
Date: Sat, 05 Sep 2009 10:39:22 +0000
From: "K1TTT" <K1TTT at ARRL.NET>
Subject: Re: [TowerTalk] NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY
To: <towertalk at contesting.com>
Message-ID: <9FBD7A0210844B22A93ABA93284EA6FE at k1tttibm>
Content-Type: text/plain; charset=US-ASCII

This sounded odd so I pulled out my belden catalog... and sure enough, right
at the beginning of the coaxial cable section are these 3 'low noise'
cables.

174/u type  8239  description: bare copper covered steel conductor,
polyethylene insulation, conductive layer, tinned copper braid shield, black
pvc jacket.

58/u type  9223  description: tinned copper conductor, conductive layer,
polyethylene insulation, duobond II tinned copper braid shield, black pvc
jacket.

59/u type  9224  description: bare copper covered steel conductor,
polyethylene insulation, conductive layer, tinned copper braid shield, black
pvc jacket.

Note that these are separate from the 'normal' 174/u mil-c-17d  8216 cable,
and the common 58/u and 59/u entries.  Unfortunately this is common with the
'rg' numbering system, there are often many manufacture variations on those.
with belden you must check the 4 digit cable type to know exactly what you
have.

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

> -----Original Message-----
> From: D.W. Fearn [mailto:dwfearn at dwfearn.com]
> Sent: Saturday, September 05, 2009 00:40
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY
> 
> I was using RG-174 as a shielded lead in a product we build and
> experienced exactly the same problem as Larry describes. This was
> from a brand-new, very expensive roll of Belden RG-174. This was to
> the grid of a tube, so even a very high resistance had an effect. We
> have changed to a Teflon-insulated coax and that solved the problem.
> 
> Doug K3KW
> 
> 
> 
> 
> 
> >Date: Fri, 4 Sep 2009 06:55:15 -0400
> >From: "Larry - K7SV" <k7sv at comcast.net>
> >Subject: [TowerTalk] NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY
> >To: <towertalk at contesting.com>
> >
> >Some of you may remember my posting about our experience with beverages
> >using plastic boxes to house matching transformers. The black plastic
> boxes
> >turned out to be conductive which obviously led to a lot of head
> scratching.
> >
> >Well, I've been working a small project using RG-174. I kept finding
> shorts
> >after putting connectors on the ends. Nothing was making sense so it got
> to
> >the point that I cut a foot long piece of the stuff, stripped back about
> an
> >inch of the outer insulated jacket at both ends and pushed the shield
> away
> >from the ends. I then took resistance measurements between the shield and
> >the ends (didn't strip back the inner insulation, just stuck the meter
> probe
> >in the end). So I'm still seeing resistance between the shield and the
> >center conductor.
> >
> >On a whim I connected a meter probe to the inner "insulation" at both
> ends
> >of the piece. Sure enough it was a conductive material. I picked up a
> couple
> >hundred feet of this stuff from Mendelson's at Dayton a few years ago. As
> it
> >turns out construction consists of an insulated black outer jacket,
> stranded
> >copper shield, a black conductive material, a light opaque insulation and
> >then the stranded copper inner conductor.
> >
> >My problem obviously existed anywhere that the inner black "insulated"
> >material was touching the shield.
> >
> >This is the first time I've experienced something like this with RG-174.
> >Actually as I think about it, the stuff must have really great isolation
> >between the center conductor and the braid! I don't think this is typical
> >RG-174!
> >
> >73 de Lar K7SV
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

------------------------------

Message: 5
Date: Sat, 5 Sep 2009 07:37:04 -0400
From: "Barry Fox" <foxbw at comcast.net>
Subject: [TowerTalk] R7 traps
To: <towertalk at contesting.com>
Message-ID: <PIEAJOGJKIOKMDLBKGKGGEHJCNAA.foxbw at comcast.net>
Content-Type: text/plain;    charset="iso-8859-1"

I'm no antenna designer, but it seems to me that if the trap capacitor
clamps were swapped such that the center rod were at the bottom, no 
water could then enter.  Would that work?
Barry - W1HFN

------------------------------

Message: 6
Date: Sat, 5 Sep 2009 08:07:33 -0700 (PDT)
From: AI4WM Bill <ai4wm at yahoo.com>
Subject: Re: [TowerTalk] R7 traps
To: towertalk at contesting.com, Barry Fox <foxbw at comcast.net>
Message-ID: <320837.15414.qm at web57905.mail.re3.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

These traps have caps on the end opposite the piston.? IF the cap is good it will keep water out.? The same for the heat shrink integrity for the piston end.? The original heat shrink has a liner that melts when the heat shrink is heated.? This makes a water tight seal IF the heat shrink was correctly heated and correctly shrunk (as it was from the factory).? 

Over time the heat shrink can deteriorate from being out in all kinds of weather.? If someone replaced the heatshrink with the regular heatshrink or used some other method of repair water can enter the capacitors.? In this case the capacitor must be taken apart and cleaned.? There are 2 good websites that detail this, just google R5 or R7 traps or trap repair.? There are cross links to the sites from several amateur radio sites also.? Here is one of the sites: 

http://www.iol.ie/~bravo/r7_vertical.htm

The capacitors are plain old coaxial capacitors and there is no electrical reason to have piston up or piston down.? The constraint comes with how the capacitor will interfere with the trap below it or above it. 

The problem would be if the brackets move and you end up with a different capacitance thus changing the frequency.

I?
have an AP8A that is very similar to the R7.? I have resonated these
on the bench and find no difference with the direction of mounting the capacitor since this was my thought on one
that was missing an end cap.? However I have found a cap and did not reverse the capacitor mounting.

73,

Bill

AI4WM

--- On Sat, 9/5/09, Barry Fox <foxbw at comcast.net> wrote:

From: Barry Fox <foxbw at comcast.net>
Subject: [TowerTalk] R7 traps
To: towertalk at contesting.com
Date: Saturday, September 5, 2009, 7:37 AM

I'm no antenna designer, but it seems to me that if the trap capacitor
clamps were swapped such that the center rod were at the bottom, no 
water could then enter.? Would that work?
Barry - W1HFN

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TowerTalk mailing list
TowerTalk at contesting.com
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------------------------------

Message: 7
Date: Sat, 5 Sep 2009 08:22:42 -0700 (PDT)
From: AI4WM Bill <ai4wm at yahoo.com>
Subject: Re: [TowerTalk] CushCraft R7 Antenna Problem
To: towertalk at contesting.com, Ray <rayn6vr at cableone.net>
Message-ID: <209003.22758.qm at web57905.mail.re3.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

One thing I forgot...
When I installed my (bought it used) AP8A it would not resonate on 20M 30M was also off.

I decided to check trap frequencies and found 17 off.? I took this trap apart (even though the 20M cap was in need of repair) and found corroded connections where the coil connects to the tubing.? 

73,

Bill

AI4WM

--- On Fri, 9/4/09, Ray <rayn6vr at cableone.net> wrote:

From: Ray <rayn6vr at cableone.net>
Subject: [TowerTalk] CushCraft R7 Antenna Problem
To: towertalk at contesting.com
Date: Friday, September 4, 2009, 12:41 PM

Recently I tried running about 600 - 700 watts to my old reliable Cushcraft
R7 vertical. Everything went fine on 20m, but when I went to 40m the SWR
became erratic, then jump to a very high level and stayed there (more than 6
- 8:1). The RX is also quite numb on 40m. The same high SWR is on 30m too.
20m is still has a good low SWR. 

It seems that there is an open or something bad at the 30m joint or coil,
but a visual inspection and ohm meter check show every think OK. I have not
yet opened the matching box at the base. I did remove the heat shrink at the
30m coil connects, but those connects are fine with no burn spots along the
coil.

Any ideas or suggests as to how to track down the problem? Sometime today or
tmw, I will look inside the matching box to see what I can find. But if
anyone as any experience or suggests, please let me know.

Ray, N6VR

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------------------------------

Message: 8
Date: Sat, 5 Sep 2009 13:48:55 -0500
From: "Mike & Becca Krzystyniak" <k9mk at flash.net>
Subject: [TowerTalk] Telrex 6M624 antenna
To: "'Joe Barnes'" <n4jbk at bellsouth.net>
Cc: towertalk at contesting.com
Message-ID: <002201ca2e59$859238c0$90b6aa40$@net>
Content-Type: text/plain;    charset="us-ascii"

Hi Joe,

    I inherited a Telrex 6M624 from an Elmer friend.  It is in pieces and
like yours needs a little refurbishing.  More importantly I'm looking for
any documentation on assembly for this antenna.  Might you have a manual or
Telrex assembly documentation for yours?

Thanks...

Mike K9MK/5

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Charlie Gallo
Sent: Friday, September 04, 2009 7:20 PM
To: Joe Barnes
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] finding aluminum tubing

On 9/4/2009 Joe Barnes wrote:

> Where oh where can I buy aluminum tubing to rebuild my telrex
> 6m624's? I have 3 bent /broke elements and apparently bin laden has
> all such tubing with him because no one knows where it is. any help would
be appreciated. Joe N4JBK

Depending on how much you need, and sizes, there is always Yarde Metals

http://www.yarde.com/index.html

No affiliation except buying some 6061 from them

-- 
73 de KG2V

For the Children - RKBA!

My Website: http://www.thegallos.com
My Blog: http://kg2v.blogspot.com

Boycott shampoo!!! Demand REAL poo!

_______________________________________________

_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

------------------------------

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End of TowerTalk Digest, Vol 81, Issue 11
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