[TowerTalk] Bury-Flex vs. LMR 400 UF, respon fr DAVIS RF

[Dick Green WC1M]

Bury-Flex may be slightly less flexible than LMR400 UF, but I've found it
perfectly suitable for high-flex applications like rotor loops. Also, the
LMR400UF jacket is so soft that it tends to work loose from the threads of a
PL-259 connector if the cable is allowed to flex in that area. This greatly
diminishes the strain relief, which in turn can lead to the braid splitting
or breaking away from the connector. The jacket on Bury-Flex is more rigid,
so it doesn't work loose.

Also, the Bury-Flex jacket is much smoother than LMR400 UF. This can make
Bury-Flex a better choice for feeding antennas on a crankup tower if your
configuration allows the cables drop through the standoffs (as opposed to
fixing the coax to the standoffs.) Buryflex slides more smoothly through the
standoffs. I found that there was so much friction between the LMR 400 UF
jacket and the standoffs that the coax would bow out quite far from the
tower when it hit the ground. Once, this caused a snag. I replaced the run
with Bury-Flex and haven't seen it bow like that since.

73, Dick WC1M

> -----Original Message-----
> From: Steve Davis -Davis RF Co. [mailto:sdavis at davisrf.com]
> Sent: Thursday, October 30, 2008 2:11 PM
> To: Tower Talk
> Cc: k5xa at godfather-ridge.com; K8RI-on-TowerTalk at tm.net
> Subject: [TowerTalk] Bury-Flex vs. LMR 400 UF, respon fr DAVIS RF
> 
> <I gave up on the Ultra flex (UF) after seen what it looked like after
> just 6 years out in the weather here in Central Michigan.  The jacket
> on
> every pigtail was split leaving the braid/shield open to the elements.
> OTOH I use and have used a lot of LMR-400 and 600 >.
> 
>    Hi John, Times LMR 400 UF uses a TPE (thermoplastic Elastomer)outer
> jacket vs. the PE (polyeth.) jacket on LMR 400.  The TPE assists in
> the flexibility; however, as you have noted, the life of TPE outdoors
> is poor.  Bury-Flex is only slightly less flexible mainly because it
> uses a PE outer jacket, which is impervious to UV, also has no
> plasticizers that will migrate into the dielectric causing havoc.  The
> PE grade that we use in Bury-Flex production is good for  25-30 years
> of outdoor service.  Lastly, Bury-Flex is noticeably less expensive
> vs. 400 UF.
> Bottom line, in my opinion, there is no reason to be using 400 UF,
> except perhaps at freq's higher than 3 GHz.
> 
> Bury-Flex has been an extremely popular item with hams, as well as
> used by entities such as Lockheed-Northrop, NASA, FAA, SPAWAR, etc.
> 
>  Please check with us for any purchases of LMR, Heliax, and many other
> cable and wire, RF conn's, etc .  that we offer at very competitive
> pricing.    Tnx to Roger for his comments and Bury-Flex support.
>    If I can ever be of any help, feel free.
> 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
> 
> 
> 
> Message: 4
> Date: Thu, 30 Oct 2008 03:53:20 -0400
> From: "Roger (K8RI)" <K8RI-on-TowerTalk at tm.net>
> Subject: Re: [TowerTalk] Bury-Flex
> To: k5xa at godfather-ridge.com
> Cc: towertalk at contesting.com
> Message-ID: <490967F0.7010402 at tm.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> John K5XA wrote:
> > Howdy from Kerrville, Texas.
> >
> > I'm about ready to order coax. I'm putting my station back together,
> and
> > have been using a combination of Andrews Heliax and LMR-400 Ultra-
> Flex.
> >   I gave up on the Ultra flex (UF) after seen what it looked like
> after
> just 6 years out in the weather here in Central Michigan.  The jacket
> on
> every pigtail was split leaving the braid/shield open to the elements.
> OTOH I use and have used a lot of LMR-400 and 600.
> 
> > I'm happy with the LMR-400, but the 1000 foot spool I've been using
> was one
> > I bought several years ago in a group purchase, for considerably
> less than
> > today's prices. So I'm considering Davis Bury-Flex as an alternative
> to
> > another order of LMR-400.
> >
> I typically purchase most coax 1000 ft at a time if starting a
> project.
> I only purchased 250 ft of Bury-flex to use for pigtails as I don't
> see
> a big need coming up for a lot of the smaller coax.  LMR-400 is
> available for slightly less than Bury-flex at a few places, but we're
> only talking a couple of cents and I don't remember how many feet
> you'd
> need for the price, plus it's approaching 4:00 AM so I don't have the
> ambition to look it up either.
> 
> Bury-flex has a very tough jacket and is quite flexible although not
> quite as flexible as the LMR-400UF cables.
> A couple weeks ago I  cut up and put connectors on 250 feet to make up
> a
> bunch of cables for "go kits". Now I have the pigtails for my beams
> and
> feed lines from the remote switches to sloping dipoles.
> 
> > Do any of you have any experience with the Bury-Flex - pro or con?
> >
> >
> I like it...So far no complaints.
> 
> 73
> 
> Roger (K8RI)
>