[TowerTalk] BURY FLEX and PE outer Jackets (also used on our ROTOR CABLE). ROPE Re: LMR 400 UF issue and Low Loss cables in general Re: TowerTalk Digest, Vol 203, Issue 15

[Bob Shohet, KQ2M]

Hi Steve,

Actually, it didn’t answer my question.  (Thanks Dick for your response and information.)  Dick is using Buryflex but you are the manufacturer and this is your product, and I wanted an answer from you based on your design and knowledge, which was why I asked you in the first place.

However, instead of answering my question you instead sent me a private email to ask me about my callsign and profession which was odd considering that it had nothing to do with what I asked in my post.  And then after I answered your unrelated question, you chose not to reply to me or provide any information. That is disappointing.

I have been using Buryflex since my large purchase from you 15+ years ago.  It has aged well but that is anecdotal – and not indicative of what the life expectancy outside should be based on your design, or the hopefully greater life expectancy for what is still on the reel inside my garage.

Your detailed comments below are helpful – you believe that it should be viable for at least 30 years.


Bob  KQ2M



From: Steve Davis | Davis RF 
Sent: Wednesday, November 13, 2019 1:31 PM
To: Dick Green RLG Analytics ; Bob Shohet, KQ2M ; towertalk at contesting.com 
Subject: BURY FLEX and PE outer Jackets (also used on our ROTOR CABLE). ROPE Re: [TowerTalk] LMR 400 UF issue and Low Loss cables in general Re: TowerTalk Digest, Vol 203, Issue 15

  Dick,  Thanks for the comments ref. Bury-Flex Tm vs. LMR-400 UF.  I think that answers Bob 's  question.

Just to add, when I designed Bury-Flex Tm I used a medium  density PE (polyethylene).  PE is highly resistive to rot, mildew, UF, various oils, chem's and gasoline.   It has a higher durometer than PVC (PVC can be had in various formulas and is most often used for flexibility and relative low cost.  Only certain formulas of PVC are UV and plasticizer migration resistant. 
DAVIS RF only uses the UV compounds of PVC for any type of cable that will be used outdoors. But again, PE has even more qualities )  

   I have Bury- Flex Tm  Buried directly in the ground, and laying on the surface in my woods to my tower.  It has been out there over 15 years.   The jacket is as shiny as new, really.   I have all the critters here in MA and they do not bother the PE outer jacket of Bury-Flex Tm.  

  We also have our various rotor cables that we sell extruded with a PE outer jacket.   We are only one of two dealers that I can find who uses PE.   The most common mfr. Of rotor cable is JSC Wire, they use a PVC outer jacket.

  So, bottom line,  PE is an excellent outer jacket material for resistance to the above noted elements.      I have not tested shelf life, or outdoor or buried life, because it has been around 15 years so far that we have had Bury-Flex Tm out there, and less years for our rotor cables, since we converted to PE.  But clearly, based on my experience and insight as a cable design engineer, I'd depend on PE jacketing to be "out there" or on the shelf for at least 30 years.

Our rotor cable with PE, as well as Bury-Flex Tm, and others, are available from many ham dealers including HRO, Universal Radio,  Texas Towers and others.

   Any questions, feel free.    Need ROPE of all types / sizes , at LOW prices, made in USA??   DavisRopeAndCable.com  (this is a totally separate company, staff and location than DAVIS RF... please contact me for either company)

73, Steve, K1PEK       Steve Davis,  DAVIS RF Co.  and  DavisRopeAndCable.com

On 11/13/19, 12:50 PM, "Dick Green RLG Analytics" <dick at rlganalytics.com> wrote:

    I've had long outdoor runs of Buryflex, both direct-buried and in the air, for more than 15 years -- probably close to 20 years -- with no degradation problems.
    
    Before going with Buryflex I used LMR400UF. I didn't use it long enough to comment on degradation, but I did have significant problems with critters chewing the cables, sometimes all the way through. I must have replaced the 100-foot run to my 4-square half a dozen times before replacing the LMR400UF with BuryFlex. I haven't had any problems with critters since.
    
    The other issue I had with LMR400UF was flexibility. I had a run going up my 72' U.S. Tower rotating tubular tower, an application that requires flexibility. I had a near-disaster where the coax migrated around the tower and got hung up on the motor control cabinet, and determined that lack of flexibility in the cable was partly responsible. I replaced the run with RG213, which is pretty flexible but higher loss. A couple of years later I did some tests with Buryflex and found that it's as flexible or more flexible than RG213. Since the loss is considerably lower, I replaced the RG213 with Buryflex and have had no problems in the 15-20 years since.
    
    73, Dick WC1M
    
    -----Original Message-----
    From: Bob Shohet, KQ2M <kq2m at kq2m.com> 
    Sent: Tuesday, November 12, 2019 2:50 PM
    To: Steve Davis | Davis RF <sdavis at davisrf.com>; towertalk at contesting.com
    Subject: Re: [TowerTalk] LMR 400 UF issue and Low Loss cables in general Re: TowerTalk Digest, Vol 203, Issue 15
    
    Hi Steve,
    
    Regarding Buryflex, what is the anticipated lifespan of Buryflex under “normal” use cndx?   How long can it be stored inside (prior to use) without significant degradation?
    
    Tnx & 73
    
    Bob  KQ2M