Commscope has been around for years, when I worked for At&t
Broadband/Comcast Cable they were the preferred vender for the coax, mainly
because they were a few cents cheaper than Times. Of course this was 75 ohm
stuff, but the Reps from both companies were kind enough to send me 50 ohms
stuff as samples, I can't think why: -), maybe because they knew I was a Ham
Radio guy.
Mike
-----Original Message-----
Steve, many thanks for your reply regarding the Commscope SFX-500.
Yours was the only reply that I received, and I have to conclude that
Commscope is a new player in the coax game and that there is not much
field experiment with it out there. Frankly, I never heard of it
before, but someone was selling 400' lengths of it for a remarkably low
price., and it sounded like it fell into the realm of "too good to be
true." My interest was piqued by my need to make an 800' run to feed an
80/160M vertical.
I gather from your description that Commscope is manufactured in China.
Based on my own experience with other types of Chinese Knock-offs, your
advice to be concerned about support, overall quality and longevity is
valid.
Thanks for the loss data and your detailed and forthright views on the
quality and product support issues.
73, Joe
K2XX
Steve Davis -Davis RF Co. wrote:
> Hi Joe and others,
>
> Here is your loss data (below). Not sure how this will reproduce on
> TT, so, for ref., the .5 MHz = .065, the 10 MHz = .293; 30 =
> .512, etc.
>
> Although Commscope is a well built cable, Andrew and LMR are also very
> well built as likely you know. Often, for various reasons, Heliax
> (LDF, etc) is overkill for hams and more costly. By overkill, I am
> not referring to attenuation, as often the alternative choices are
> very close to same attenua. Overkill is as to the extra strength (and
> cost vs. comparable LMR) of Heliax (for hauling up very high
> commercial towers) and crush resistance (if you plan to drive your car
> over it day in day out... HI).
>
> Bend radius is larger ("worse" depending on the installation issues)
> for Heliax vs. similar size LMR (and the bend rad will be same or
> close to for the other Heliax similar constructions like RFS and
> Eupen, etc). The bend radius on this Commscope is 1.25", LDF4 is
> 5 ", and LMR-400 is 1" (but I always recommend adding about 1" to
> these bend radius's to be safe).
>
> Thus, this Commscope is the same build as LMR ; i.e., not the more
> expensive "corrugated" build of Heliax (or RFS, Eupen, etc).
>
> Attenuation wise, comparing the .5" Heliax is not a good comparison
> because LMR-400 is a .405" OD which increases the attenuation (given
> that the dielectrics and ctr. conductor is fairly equal). Thus LMR
> 400 at 30 MHz is .7 dB per 100 ft and .512 for this Commscope vs.
> .357 for LDF4 .
>
> Obvious conclusion: It appears that your "below 150 MHz" data
> interest indicates usage at HF, as most readers here are involved
> with. At HF, a choice between LMR and Commscope is almost a
> non-consideration...they are so close in attenuation that I highly
> doubt you would ever make or break that last contact for DXCC. The
> cost differential of these two vs. LDF4 would be significant.
> The cost of connectors, and bend radius install issues of Heliax, also
> significant.
>
> Lastly, a better comparison to LMR-400 or Commscope SFX-500,
> attenuation wise, is LMR-600: .4 dB/c ft at 30 MHz and 1.5 "
> Bend rad (add 1" for safety) .
>
> 10 MHz attenua: Commscope SFX-500: .52
> LMR 400: .43
> prox (from Times graph, not from formula
>
> $ .79/ ft from DAVIS RF Co.
> LMR 600: .27
> prox $ 1.56/ft DAVIS RF Co.
> LDF4-50A: .205 $
> 2.21/ft DAVIS RF Co.
>
> Bottom line: Commscope vs. LMR: Davis RF sells quality and
> reputation. LMR is made in CT, to high quality stds. It's been around
> some 30 or more years. Many knock offs of LMR are out there and I
> know some of the factories. We won't sell them. Yes, you can
> save money on the knock offs, and you are welcome too as long as you
> test them to the same degree that would support comparison to LMR.
> Installing cable is only a real pain when you have to trouble shoot
> it, go up that tower, or hire a guy to futz with it in the middle of
> CQ World Wide, or dead of winter. Then there is the little addage,
> that some of us take sincerely to heart, "By American". Yes, I know
> the reports on here of having success with the knock offs, but who has
> really tested them completely, and who has had that cable up for 5 or
> 10 + years???. With LMR PE jacketed, or DAVIS RF Bury-Flex Tm, I'll
> give you a good 30 + years of life. And also, I will take the time
> to give you complete info (as above) before, during and after your
> purchase ... do you see Commscope, Tessco, etc. on here, or do you
> have somebody there to consult?? (Sorry, that's another subject:
> What RF qualified ham engineers (vendors) are supporting you, and are
> you "supporting " them ??? ) Note: Joe, not directed at you .....HI
>
> If I can answer any further questions for you or anybody on TT, just ask.
> 73, Steve , K1PEK,
>
> DAVIS RF Co., Div. of Orion Wire Co., Inc.
>
> Wire, Cable, RF Connectors and wire aerial parts. LMR, Heliax, Eupen
>
> Commercial / Military / & Custom Cable Design
>
> tel: 978-369-1738 Fax: 978-369-3484
> www.DavisRF.com
>
>
> Commscope SFX-500:
> .................................................... atten dB/100
> ft...............................
> 0.5 0.213 0.065 15.60
> 1 0.302 0.092 15.60
> 1.5 0.37 0.113 15.60
> 2 0.428 0.13 15.60
> 10 0.962 0.293 8.97
> 20 1.367 0.417 6.32
> 30 1.68 0.512 5.14
> 50 2.18 0.664 3.96
> 88 2.913 0.888 2.96
> 100 3.112 0.948 2.77
> 108 3.238 0.987 2.67
> 150 3.838 1.17 2.25
>
>
>
> 73, Steve K1PEK
>
>
>
>>
>> Message: 6
>> Date: Sat, 06 Jun 2009 14:48:40 -0400
>> From: Joe Giacobello <k2xx@swva.net>
>> Subject: [TowerTalk] 1/2" Commscope 50 ohm hardline (SFX-500)
>> To: towertalk@contesting.com
>> Message-ID: <4A2ABA08.1030905@swva.net>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Anyone have experience with this hardline? Its attenuation at 150 MHz
>> is 1.2 dB vs about 0.9 db for LDF4-50a and 1.5 for LMR-400. There are
>> no data available for frequencies below 150 MHz.
>>
>> 73, Joe
>> K2XX
>>
>>
>> ------------------------------
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>>
>> End of TowerTalk Digest, Vol 78, Issue 23
>> *****************************************
>>
>>
>
>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.339 / Virus Database: 270.12.54/2159 - Release Date: 06/07/09
05:53:00
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|