[TowerTalk] PS PS to my last CONTAM-UV Fw: LMR400 vs BuryFlex, Response DAVIS RF, Designer of Bury-Flex ^^

Thu May 29 12:32:28 EDT 2008

Rudy, I didn't answer a couple of your points as directly as I should have, and they are pertinent ref. attenuation , cost , your ref'd "contamination" and UV.  Also, in retrospect, I think that you may be confusing contamination or UV issues (separate)  of LMR-400 UF, vs. LMR 400.  Bear with me as this subject often comes up and is confusing to many.  Hopefully I can resolve it , without creating more confusion. 

  Your conclusions are well founded based on some info out there....and as far as pricing you may not have also found the best pricing on LMR-400.

   In summary,, the following will show that there is very little difference in the price comparison; that the attenuation is almost nill (at Mid HF, and even less at lower freq) and that "contamination" strictly has to do with using the wrong type PVC or TPR, and that it strictly refers to migration into (vs. outside of) a coax cable.  Lastly, PE jacketing that we, and Times, utilizes, will not contaminate the coax dielectric..., important to avoid).  

Based on the pricing I mentioned, your cost difference, based on our pricing is considerably less if bought from us (or from our dealers of Bury-Flex, assuming our dealers also sell LMR 400, some don't..... if so, buy the B Flex from them, see us about the LMR).  As noted in the last, our cost of Bury -Flex vs. LMR 400 is only  6 cents per foot  ($ 60 per 1,000 ft. vs. your noted $ 150 prox.  And actually, if you are buying more than 500 ft. of Bury Flex,  the price is even less (LMR400 is still the same price up to a few thousand ft)  

 Ref. the attenuation:  given that you mention yagi's, I can reasonably assume that you are using 15 m. nominal for computing  the ref'd attenuation figure.  Your figure is pretty much on, if that is the case,  .3 dB/ 100 ft. varies application to application needs basis, in significance, albeit a very small difference in the two cables. Virtually no difference at lower freq's.

  Non-Contaminating issue:  PE vs. TPR:  My comments were indirect to this, when I say 15 yr avg. for TPR (LMR400 UF only)  vs. 25 + yrs for PE (Bury-Flex),I am actually generous vs. Times stated info : 
 Per Times,  "LMR-400 UF:  ... weatherability:  designed for outdoor exporsure and has a life expectancy in excess of 10 yrs"  .  NOTE:  There is no mention as in their LMR-400 standard product (PE jacket),  of,   "... incorporates the best material 
for UV resistance and life expectancy in excess of 20 years".  (again, for PE vs. their TPR).
 As far as "contamination", that is a different matter:  this is a commonly mixed up term by "the public", so to speak.  In cable engineering, "contamination" strictly refers to what happens if certain chems in the outer jacket material are such that they are prone to "migrating" from that jacket, into the inners of the cable (thru the shield(s) and into the dielectric material (surrounding the center conductor)   Such contamination will significantly affect the electrical specs of the cable...a real problem.  
 With the most commonly used PVC outer jackets, unless a specific type of PVC compound is used (often ref'd to as "IIA", that does not incorporate plasticizers that will migrate, thus harming  (contaminatiing), therein lies the problem. 
 Anti-migrating/contaminating compounds cost more. Thus not all PVC's are created equal. Same for TPR.   Thus, TPR is more prone to UV breakdown of the outer jacket, vs. PE.  Thus the lower life span.  PE however is NOT prone to contamination because it has no plasticizer ingredients that cause contamination...AND, it's one of the least prone to UV deterioration.   

   You don't need to worry about "contamination" from the cable to the tower (alum or steel).  Their can be some contamination if a contaminating type PVC or TPR is mounted against other cable jackets; however that is relatively insignificant as to the damage, or to the probabilityh of contaminating from one jacket, to and thru the adjacent,  other jacket, into the conductor jacketing of control cable inners, or into the dielectric of coaxes.   You mentioned using conduit, thus not tightly bound cables, I wouldn't worry at all.

Hope this helps,   Steve   K1PEK
   978-369-1738   
~ Davis RF Co., Div. of Orion Wire Co.,Inc.
Distribution to numerous industries,  Andrew 
Heliax; Times Microwave LMR; RFS Celwave and others.
Cable design engineering. RF Peripherals.
www.davisRF.com
Tel: 1-800-328-4773 (1-800-DAVIS RF) Tech'l: 1-978-369-
1738, Fax: 1-978-369-3484 

~ DAVIS/ORION Marine Wire and Cable Co., Distribution and Design: UL/USCG Marine Stds.  Tel: 877-242-2253  Fax: 603-787-2221 (Direct tel to Steve Davis: 978-369-1738 or Fax: 978-369-3484)

~Orion Wire Co., Inc., Design Engineers of Specialty/Custom Cable
Tel: 1-800-328-4773, 1-603-787-2200 Fax 1-603-787-2221,
email: j_stimson at davis-orionwiregroup.com
www.davisRF.com
----- Original Message ----- 
From: Steve Davis -Davis RF Co. 
To: r_bakalov at yahoo.com ; Tower Talk 
Cc: Jeff ; Kyle ; aaaNicole ; astaceyjones ; aKay 
Sent: Thursday, May 29, 2008 11:05 AM
Subject: LMR400 vs BuryFlex, Response DAVIS RF, Designer of Bury-Flex ^^

Hi Rudy, 
Possibly this will help you and others:  We sell  LMR, and also  Bury-Flex Tm, which I designed over 10 years ago.   Bury Flex Tm has become one of our best sellers and is bought by many hams as well as NASA, Lockheed Martin, SPAWAR, etc., as our core business is commercial.

  Outer jacket on both:  Polyethylene ("PE") of very similar if not virtually the same chem. composition, 400 and Bury-Flex.  If you are also thinking of LMR-400 UF (ultra flex), that outer jacket is TPR, not PE, and will not last as long as PE in UV.  TPR, on avg. in USA might be 15-18 yr life, approx, whereas quality PE will go at least 25 yr and more.
   Attenuation and MUF:  Although Times spec is 16 GHz, and not to chide them as they do a great job, we don't recommend it over 8 GHz, for various reasons.  Bury-Flex Tm:  I don't recommend it over 3 GHz.   For up to 3 GHz, both attenuations are very close to each other.  For HF, not even worth comparing, virtually the same.
   Flexibility:  Bury Flex definitely has it over LMR 400 and is only a slight perception less flex than Ultra Flex 400....again, not a distinctive difference. 

NOTE:  the TPR jacket of Ultra Flex ("UF") is not nearly as good for low-friction to metal, i.e., to the tower, etc.  In fact, Bury Flex is EXCELLENT for a coil around the tower for crank ups.  UF is not.   
   Pricing:  We have quite low pricing on LMR 400  and UF  (presently .81 avg for Bury Flex vs. .75/ft LMR 400    (400 UF is $ 1.13)   List on 400 is .88 and 400 UF is 1.33)    Prices can vary periodically primarily due to copper fluctuations and mfr. price changes.
   PE  vs. TPR or PVC:   PE is relative rodent resistant, a strong application point for many hams.  This is why we were first to convert our control cables (not all) for rotators, etc., to PE outer jackets.  And the cost difference is minimal.  
Bottom line:  PE is much tougher (higher durometer) than PVC or TPR. You will quickly learn this when cutting into a PE jkt with a new razor blade:  PVC will be like butter, PE much tougher (but not a pain if you use a sharp safety razor), thus  PE is much more abrasion resistant , and can be laid thru ponds/rivers, etc..... PVC can not be as so, it is only "moisture resistant"...not "water proof" (varies with mfrs., some mfrs ref. their PE to be "highly moisture resistant")  

   My strict advice over the years:  don't "skimp, save a dime, etc." on your 
cable and connectors.  It is not worth the hassle of repair/replace in the middle of winter, up a tower, in the middle of that contest or contact with rare DX.  Your best system results/success, as all members of this forum know, is first with the antenna system, working back from there.  Lastly, make SURE that your connectors are installed properly (we can do that for you if you are of many who can't stand the process, N, BNC, UHF, etc etc)  AND that they are sealed extremely well from the elements (again "moisture proof" vs. "water proof", doesn't hack it in my book...needs to be "water proofed").....plenty of archive info on TT ref this subject. 

Bury-Flex has been extremely popular over the years with hams, and the commercial biz.  But again, we have excellent prices on LMR types, same to next day shipment 99% of time on either (tend to have back orders occasionally on Bury Flex) and excellent customer service...we smile, never blasé....HI

 Soon to be released to TT, etc:  I have promised many of you the following, now done and just in line to get onto the site (I can't respond to email requests for this now, will let you know when on DavisRF.com:   Decision criteria for choosing between various options of 1/2" and 7/8" OD Hard line... all product options avail, and which give similar electrical/mechanical results:  one fairly new product which is a DISTINCT cost savings in the 7/8", equal performance  to LDF5 (Now AVA5) Andrew Heliax product. 

  I will check with Steve to see if I can attached is a spec to a TT submission ( ref. Bury-Flex Tm), also will be on DavisRF.com I hope in near future (many site priorities).  

    Please support your dealers who know what they are doing, are there for you, and not simply clerical reps who dispense price per part #.   There is a lot to be said for "you get what you pay for".  

As usual, feel free to contact me with any question or input you can share with me...always welcomed. 

  Cheers, Steve   K1PEK    
  978-369-1738   
~ Davis RF Co., Div. of Orion Wire Co.,Inc.
Distribution to numerous industries,  Andrew 
Heliax; Times Microwave LMR; RFS Celwave and others.
Cable design engineering. RF Peripherals.
www.davisRF.com
Tel: 1-800-328-4773 (1-800-DAVIS RF) Tech'l: 1-978-369-
1738, Fax: 1-978-369-3484 

~ DAVIS/ORION Marine Wire and Cable Co., Distribution and Design: UL/USCG Marine Stds.  Tel: 877-242-2253  Fax: 603-787-2221 (Direct tel to Steve Davis: 978-369-1738 or Fax: 978-369-3484)

~Orion Wire Co., Inc., Design Engineers of Specialty/Custom Cable
Tel: 1-800-328-4773, 1-603-787-2200 Fax 1-603-787-2221,
email: j_stimson at davis-orionwiregroup.com
www.davisRF.com

From: Rudy Bakalov <r_bakalov at yahoo.com>
Subject: [TowerTalk] LMR400 vs BuryFlex
To: towertalk at contesting.com
Message-ID: <114702.13331.qm at web43137.mail.sp1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Date: Wed, 28 May 2008 18:44:33 -0700 (PDT)
From: Rudy Bakalov <r_bakalov at yahoo.com>
Subject: [TowerTalk] LMR400 vs BuryFlex
To: towertalk at contesting.com
Message-ID: <114702.13331.qm at web43137.mail.sp1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Hello all,

   As I am getting closer to having the new tower and antennas go up, 
questions that I have never considered in the past keep on coming 
up.  One of them is the choice of coax.

   As the title suggests, I am trying to decide between LMR400 and 
BuryFlex.  I estimate that I will need a total of 1000' to connect 
all 4 beams, the phasing lines, 2 cables to the shack, etc.  The max 
distance between an antenna and the shack will be less than 300' (or 
0.3db loss).

   I like the LMR400 option due to its lower cale loss and 
cost.  However, I don't understand the practical impact of the fact 
that LMR400 is NOT non-contaminating- is there going to be any impact 
from bundling cables, attaching them to the tower legs, etc.?  The 
cables will go in a PVC conduit between the tower and the shack.

   I do recognize the difference in flexibility (and its 
applicability to rotating antennas) and my solution is to have a 10' 
BuryFlex attached to each yagi, followed by whatever length of 
LMR400. I have to install Polyphaser coax in-line protectors anyway 
and I will install them between the 10' BuryFlex and LMR400 sections.

   Any thoughts?  The difference in cost is about $150 at 1000'

   Thanks,

   Rudy N2WQ