I had an M2 40/30M 4 el linear loaded beam up about 6 years at W0ID - 2 full
miles above sea level on the continental divide. Subject to wind, rain, lots
and ~25 ft of snow/year.
Also had the M2 6el 20M full size on 60+ foot boom up for about 7 years.
Both worked gang-busters (pileup busters?) ~{ ;-) & were taken down fall
2007 & moved to Blue Ridge country of VA.
IMHO Mike's construction is top-of-the-heap rugged. Never had an element
slip or rotate, etc. Based on results, the 4el shorty seemed to be, as the
specs suggest, very close to a 3 el full size in performance.
Think it's a good idea generally to keep a small, low-Q reversible and
adjustable "L" network in-line with each beam as an easy and quick way to
compensate for SWR problems toward band edges or due to weather. Got the
idea from Paul Bittner, W0AIH, who builds such L-net single-banders in small
paint cans & leaves them in-line. Sure, gain and pattern no doubt vary some
across the bands and with certain weather, but the simple "L's" keep any amp
happy, short of actual feedline or antenna failure.
I never felt that on-air results were significantly affected by moderate
VSWR and/or resonance variations, even back when we had to deal with the
monstrous domestic QRM from 7.15 to 7.3 MHz.
Good luck!
Dick
--------------------------------------------------
From: <towertalk-request@contesting.com>
Sent: Tuesday, November 09, 2010 12:27 PM
To: <towertalk@contesting.com>
Subject: TowerTalk Digest, Vol 95, Issue 18
> Send TowerTalk mailing list submissions to
> towertalk@contesting.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
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> or, via email, send a message with subject or body 'help' to
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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. Re: Adjusting a Gamma Match on a Yagi with an AntennaAnalyzer
> (n8de@thepoint.net)
> 2. Re: Quads (Glen)
> 3. M2 40M2L (Shane Mattson-->K1ZR)
> 4. Re: M2 40M2L (W2RU - Bud Hippisley)
> 5. Re: M2 40M2L (Grant Saviers)
> 6. Re: M2 40M2L (Tim Duffy K3LR)
> 7. Re: Phillystran Questions (Joe Giacobello, K2XX)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 09 Nov 2010 08:25:38 -0500
> From: n8de@thepoint.net
> Subject: Re: [TowerTalk] Adjusting a Gamma Match on a Yagi with an
> AntennaAnalyzer
> To: Chuck <w5pr@swbell.net>
> Cc: towertalk@contesting.com
> Message-ID: <20101109082538.a5zohj0nk8w0400k@webmail.win.net>
> Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
> format="flowed"
>
> Quoting Chuck <w5pr@swbell.net>:
>
>>
>> I do have a series capacitor.
>
> Is it adjustable? If not, why not?
>
>> I was giving you the design impedance without
>> the gamma match
>
> Design impedance with split driven element or what?
>
>> and the measured impedance.
>
> Measured with what gamma configuration and capacity?
>
>> I used one wavelength of feed
>> line so I could get the antenna off the ground. It is a multiple of 1/2
>> wavelength which should reflect the same impedance as the feed point.
>
> That's totally understandable .. but what is it really telling you?
> Seems to me the gamma capacitor needs to be adjusted to make the
> inductance = 0, but at what frequency?
>
> Remember, whether you want to do it or not, you MUST do the
> 'back-and-forth' adjustments between shorting bar and capacitor as
> each affects the other.
>
> I'm not sure there is ANY other way ... in my 50+ years of experience
> designing/building yagi.
>
> 73
> Don
> N8DE
>
>
>>
>> Chuck W5PR
>>
>> Whoa.
>>
>> A gamma match has TWO things to 'change' ... one is the point of
>> attachment from gamma rod to the driven element ... the other is the
>> SERIES CAPACITOR in the gamma line.
>>
>> All gamma matches that I use are tuned by placing the antenna analyzer
>> about ONE FOOT from the feedpoint, then going back and forth between
>> the capacitor and the shorting bar .. until the match is what I want
>> it to be.
>>
>> The inductive portion of your measurement seems to be due to NOT
>> having a series capacitor in the gamma match.
>>
>> 73
>> Don
>> N8DE
>>
>> Quoting Chuck <w5pr@swbell.net>:
>>
>>> I hate adjusting gamma matches through trial and error. I am hoping my
>>> new antenna analyzer will help.
>>>
>>> I computer designed a 10 meter Yagi which designed at a feed impedance
>>> of 31.2 + j18.3. This is inductive, I assume.
>>>
>>> I have a gamma match, the antenna mounted at 15 feet and my antenna
>>> analyzer says (through an analyzer measured 1 wavelength 50 ohm feed
>>> line) Z=66 ohms, X=-52 ohms and C=105
>>>
>>> My take is to move the tap closer to the boom until it is about Z=50
>>> ohms
>>> and, if there is still a negative X, to lengthen the DE. Of course,
>>> the
>>> changes will interact with each other and I will need to go back and
>>> forth until Z=50 and X=0.
>>>
>>> Am I on the right track?
>>>
>>> Chuck W5PR
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 9 Nov 2010 08:48:52 -0500
> From: "Glen" <k4kv@mds-ham.com>
> Subject: Re: [TowerTalk] Quads
> To: "Tower Talk" <towertalk@contesting.com>
> Message-ID: <OLEMLLLENPOJJLABJGKJKEOPGLAA.k4kv@mds-ham.com>
> Content-Type: text/plain; charset="US-ASCII"
>
> Hello,
>
> After my 4th quad in 40 years, this last one covers from 30M to 6M.
>
> It is a spider type design, with optimum element spacing.
>
> I found with this last one, with all the WARC bands, it seems to lower the
> impedance.
> I found them closer to 70 ohms not 90, and removed all the matching
> sections. I used a tower
> mounted coaxial switch. The match is quite good without matching
> sections.
>
> 73's
>
> Glen K4KV
>
>
>
> Tom
>
> I think that you need to know the impedance of your antenna first before
> think
> to use a matching section to adjust it to your coaxial.
>
> I have a 6 band quad 6-20m and only in 12m is needed the matching section
> all
> the others bands are direct feed to 50 ohms
> the antenna design was to have the direct feed to 50 ohms coax, the
> impedance
> is around 45-60 ohms in the bands and most of them reach the 1:1.1
>
> each loop is feed with a piece of coaxial cable to the remote antenna
> selector.
>
> More info about my antenna that was designed by Robert KG6B (I took
> advantage
> of his work and build mine first ) he have a photo of his antenna and
> all the related things in his web page http://www.kg6b.com/
>
> I have another 6m quad old design and that also feed direct to 50 ohms,
> from
> the packet.com
>
>
> Another great source of Quads mono band and long boom are in the W4RLN
> books
> Cubical Quad.
>
> Also a few clues of how you can get a direct feed to 50 ohms with
> broadband
> in
> quads (yagis also) is www.g0ksc.co.uk he is great in the design and
> modeling antennas
>
> Hope you learn a few new things of the quads modeled with powerful
> computer
> software.
>
>
>
>
>
> J.Hector Garcia XE2K / AD6D
> Mexicali B.C DM22fp
> P.O.Box 73
> El Centro CA 92244-0073
> http://xe2k.net
> http://dxxe.org
>
>
>
>
>
>
> ________________________________
> From: Tom Horton <k5iid@sbcglobal.net>
> To: antennas@mailman.qth.net; Tower Talk <towertalk@contesting.com>;
> ctdxcc@kkn.net; ntcc@yahoogroups.com; ham-antennas@yahoogroups.com
> Sent: Mon, November 8, 2010 8:41:16 PM
> Subject: [TowerTalk] Quads
>
>
>
>
>
>
> I've been using Quads for many (50+) years. Previously I have always used
> 1/4
> wave matching transformers.
> But this time when it went up, I purchased a commercial matching
> transformer.
> Well, when it was installed, it was open. So, for a temporary fix, the 20
> and 17
> meter elements were attached to the feedline directly. The antenna seems
> to
> perform quite well even in this hookup.
> I am tempted to just hook all the elemments to the feedline without a
> matching
> device of any kind.
>
> I have read many things written about doing this and it seems that all
> seem
> to
> have favorable results.
> I am interested in hearing from fellows that have done this and what their
> results were.
> Thanks,
> Tom K5IID
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 9 Nov 2010 10:11:48 -0500
> From: "Shane Mattson-->K1ZR" <k1zr@comcast.net>
> Subject: [TowerTalk] M2 40M2L
> To: <towertalk@contesting.com>
> Message-ID: <35E5312F817242ACBB67164F073CFB96@MAIN>
> Content-Type: text/plain; charset="us-ascii"
>
> Any M2 shorty 40 owners out there? I'm soliciting your feedback on the
> performance/construction/maintenance etc as I'm considering purchasing
> this
> antenna. Any comparisons to the Cushcraft XM240 would be helpful as well.
> My plan is to install a 2EL 40 at 100' on a hilltop in southern NH in a
> high-wind zone.
>
> TNX.
>
> -Shane K1ZR
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 9 Nov 2010 11:27:49 -0500
> From: W2RU - Bud Hippisley <W2RU@frontiernet.net>
> Subject: Re: [TowerTalk] M2 40M2L
> To: Shane Mattson-->K1ZR <k1zr@comcast.net>
> Cc: towertalk@contesting.com
> Message-ID: <FE85FA8C-1FBA-4AF5-8EB8-C8E2B330AD9A@frontiernet.net>
> Content-Type: text/plain; charset=us-ascii
>
> I live in the Adirondack Mountains of upstate NY, with weather fairly
> similar to central NH. I own both a 40-2CD (predecessor to the XM240) and
> an M2 40M2LL (linear loaded elements). In the past, I've owned a Mosley
> S-402 (discrete loading coils at the element centers), a Hy-Gain (can't
> remember the model #, but it had linear loading, as well), and full-size
> 2-element and 4-element 40-meter monobanders.
>
> I believe the M2 shorty 40 is mechanically far superior to the 40-2CD. So
> much so, I would far sooner have that 40-meter antenna at the top of my
> tower than any of the others I've used. Electrically it is not superior,
> however, because ice and snow will cause the frequency of minimum SWR to
> move more than 50 kHz. I can't say for sure how far, since my "dry
> weather" minimum SWR frequency is 7.050, and sometimes in the winter it
> drops below 7.000. Most of the year I was unable to run legal limit with
> my Alpha 99 because the reflected power protection circuit would kick it
> off the air on the low end of the band, but there have been times during
> the winter months when accumulated ice allowed me to get back to 1500
> watts.
>
> It is my OPINION, based on rather rudimentary and not always consistent
> S-meter measurements of received signal strengths while rotating the
> 40M2LL, that the "dry weather" forward gain of my 2-element array
> disappears by the bottom of the band (with the beam assembled with the
> 7.050 dimensions). Next time I take it down, I'll make some element
> changes to move the sweet spot on the forward gain curve down 25 kHz or
> so, but I have some serious EZNEC modeling work to do first.
>
> Despite its mechanical limitations, my 25-year-old 40-2CD was a phenomenal
> performer year-round until about four years ago, when a massive October
> ice storm broke it into smaller parts. That's when I switched to the M2.
> If I ever get any spare time one of these years, I'll finish rebuilding
> the 40-2CD with the W6NL strengthening mods so I can put it back up. One
> can never have enough aluminum up in the air.
>
> I'm not familiar enough with the XM240 to know if it has any strengthened
> members a la W6NL, but if that's the direction you choose, I'd make sure
> it does or I'd add some before putting it up. Ice storms are no stranger
> to your part of the country!
>
> Bud, W2RU
>
>
> On Nov 9, 2010, at 10:11 AM, Shane Mattson-->K1ZR wrote:
>
>> Any M2 shorty 40 owners out there? I'm soliciting your feedback on the
>> performance/construction/maintenance etc as I'm considering purchasing
>> this
>> antenna. Any comparisons to the Cushcraft XM240 would be helpful as
>> well.
>> My plan is to install a 2EL 40 at 100' on a hilltop in southern NH in a
>> high-wind zone.
>>
>> TNX.
>>
>> -Shane K1ZR
>
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 09 Nov 2010 08:32:45 -0800
> From: Grant Saviers <grants2@pacbell.net>
> Subject: Re: [TowerTalk] M2 40M2L
> To: "Shane Mattson-->K1ZR" <k1zr@comcast.net>,
> towertalk@contesting.com
> Message-ID: <4CD977AD.80208@pacbell.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> I'm also in the market for a 2el 40m beam, so would appreciate inputs.
> The W6NL Moxon mods to the XM240 look particularly interesting, anybody
> build one?
>
> My beam will be at 92' among the tall pines of Redmond, WA so am not as
> concerned about wind exposure as K1ZR.
>
> Grant, KZ1W
>
> On 11/9/2010 7:11 AM, Shane Mattson-->K1ZR wrote:
>> Any M2 shorty 40 owners out there? I'm soliciting your feedback on the
>> performance/construction/maintenance etc as I'm considering purchasing
>> this
>> antenna. Any comparisons to the Cushcraft XM240 would be helpful as
>> well.
>> My plan is to install a 2EL 40 at 100' on a hilltop in southern NH in a
>> high-wind zone.
>>
>> TNX.
>>
>> -Shane K1ZR
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
>
> ------------------------------
>
> Message: 6
> Date: Tue, 9 Nov 2010 11:01:10 -0600
> From: "Tim Duffy K3LR" <k3lr@k3lr.com>
> Subject: Re: [TowerTalk] M2 40M2L
> To: "'Grant Saviers'" <grants2@pacbell.net>, "'Shane Mattson-->K1ZR'"
> <k1zr@comcast.net>, <towertalk@contesting.com>
> Message-ID: <F4AB59237C7846FCBD6381C1D6DED491@laptop>
> Content-Type: text/plain; charset="us-ascii"
>
> Hello Grant!
>
> Here are two papers on the conversion of the XM240 to W6NL/Moxon.
>
> http://www.k3lr.com/engineering/moxon/W6NL_Mox_100.pdf
>
> http://www.k3lr.com/engineering/moxon/W6NL_Moxon104.pdf
>
> Here are photos of two W6NL/Moxon's installed at K3LR
>
> http://www.k3lr.com/2009/CQ09CW/IMG_5361.jpg
>
> http://www.k3lr.com/2007/photos/new20.jpg
>
> Performance is outstanding
>
> 73,
> Tim K3LR
>
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Grant Saviers
> Sent: Tuesday, November 09, 2010 10:33 AM
> To: Shane Mattson-->K1ZR; towertalk@contesting.com
> Subject: Re: [TowerTalk] M2 40M2L
>
> I'm also in the market for a 2el 40m beam, so would appreciate inputs.
> The W6NL Moxon mods to the XM240 look particularly interesting, anybody
> build one?
>
> My beam will be at 92' among the tall pines of Redmond, WA so am not as
> concerned about wind exposure as K1ZR.
>
> Grant, KZ1W
>
> On 11/9/2010 7:11 AM, Shane Mattson-->K1ZR wrote:
>> Any M2 shorty 40 owners out there? I'm soliciting your feedback on the
>> performance/construction/maintenance etc as I'm considering purchasing
> this
>> antenna. Any comparisons to the Cushcraft XM240 would be helpful as
>> well.
>> My plan is to install a 2EL 40 at 100' on a hilltop in southern NH in a
>> high-wind zone.
>>
>> TNX.
>>
>> -Shane K1ZR
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> ------------------------------
>
> Message: 7
> Date: Tue, 09 Nov 2010 12:27:01 -0500
> From: "Joe Giacobello, K2XX" <k2xx@swva.net>
> Subject: Re: [TowerTalk] Phillystran Questions
> To: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
> Cc: towertalk@contesting.com, "k4za@juno.com" <k4za@juno.com>,
> john@kk9a.com
> Message-ID: <4CD98465.4000903@swva.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Thanks, Roger, Don and John. I now understand that what I was
> observing was the compression of the jacket and no cutting was actually
> taking place. It was that the compression was so deep, it looked as
> though the cable was being cut and weakened.
>
> My major problem and worry now are those end caps. (I had absolutely no
> idea that the Phillystran was so moisture sensitive.) There's no
> problem installing them at ground level where the guys attach to the
> anchors, but the other ends are in the air. Lowering this tower is not
> a trivial exercise, although it could be done. I used a tow truck to
> tilt it up. I guess I'm going to have to call him back.
>
> Thanks for all your help. Obviously, I should have consulted earlier.
>
> 73, Joe
> K2XX
>
>
>
> On 11/9/2010 1:32 AM, Roger (K8RI) wrote:
>>
>> On 11/8/2010 12:21 PM, Joe Giacobello, K2XX wrote:
>>> I had never used Phillystran before, but am currently using the
>>> light
>>> duty grade (1200 lb. tensile) for stabilizing a long aluminum tubing
>>> stinger atop an aluminum tower.
>>>
>>> Based on recommendations from the supplier and info from this forum, I
>>> used 1/8" (or 3/16"?)
>> 3/16"
>>> cable clamps to secure the ends of the
>>> Phillystran. They had been in place for about a month when I undid one
>>> set to make some adjustments to the guy. I noticed that the clamps had
>>> compressed or made deep cuts in the the Phillystran so that it appeared
>>> that its strength was probably compromised.
>> Probably less than with wire rope. Remember there is a right way and a
>> wrong way for the clamps to be installed.
>> First, the compression is normal within reason. The Phillystran is at
>> least 2/3rds jacket with a small Kevlar core. The jacket and end caps
>> protect the Kevlar from moisture to which it is very sensitive. As long
>> as the compression is not over done it really takes place in the
>> jacket. The cable clamps go with the U-bolt on the dead side (side
>> with the end of the cable) and the flats on the load bearing side. It
>> takes 3 of the cable clamps about 2" to 3" apart. Use a nut driver and
>> just snug the nuts on the cable clamps.
>>
>> Yes the cable calms do reduce the load bearing capability of the cable,
>> but not all that much with Phillystran.
>> I use a lot of the 1200# test Phillystran for odd jobs but go for at
>> least the 4000# test for most load bearing towers.
>>
>>> When I reclamped the
>>> adjusted cable, I didn't tighten the clamps to the same degree as I had
>>> originally because of my concern for cutting into the cable. I'm
>>> wondering whether these cuts are normal
>> Cuts would not be normal, but I'm assuming you are referring to the
>> indentations caused by compression of the jacket and not actual cuts.
>> If they are cuts it's time to pitch the cable.
>>> and don't seriously reduce the
>>> strength of the installation or not?
>> The strength of Phillystran is in the Kevlar core, not the protective
>> jacket.
>>> Should I have used a torque wrench
>>> or similar to tighten the clamps?
>>>
>> It'd need to be a pretty small torque wrench as you only snug them with
>> a nut driver.
>>> Also, end caps were supplied for the cable. Are these merely decorative
>>> or do they serve some other function?
>>>
>> They are very important. Don't ever leave Phillystran outside where
>> moisture can collect without the end caps *sealed* on. If a coil of
>> Phillystran has been exposed to moisture without the end caps its
>> integrity is doubtful and lifetime seriously shortened. Those caps need
>> to be *sealed* on.
>>> I'd appreciate any info that the forum can provide.
>> If it's been exposed to moisture it's likely that within a year or two
>> the strength will only be a fraction of its original rating.
>>
>> 73
>>
>> Roger (K8RI)
>>> 73, Joe
>>> K2XX
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>>
>
>
> ------------------------------
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> End of TowerTalk Digest, Vol 95, Issue 18
> *****************************************
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