On 2/23/2013 11:53 AM, Jim Brown wrote:
On 2/23/2013 8:41 AM, Mike Reublin wrote:
Please do yourselves a favor and look at Davis BuryFlex.
http://www.davisrf.com/buryflex.php
Yes.
Also, download and study my tutorial on Coax and Stubs.
http://audiosystemsgroup.com/Coax-Stubs.pdf
LMR400 and similar cables are OK, but not worth their additional cost
for use on the HF bands.
Check vendors and quantity prices if there is a chance you or you and a
friend might get enough for a substantial discount.
The last Times Wire LMR-400 I purchases was cheaper than Belden's cable,
but I did purchase 1000 feet.
However there are reasons for selecting coax other than loss, or even
avoiding specific coax
The "Davis BuryFlex(TM)" is an excellent and very rugged coax. It has
an extremely tough and "slippery" jacket and is reasonably flexible with
loss figures very close to LMR400. It's also easily prepped due to that
tough jacket. Although not a "flooded" design, the tough jacket makes it
a good candidate for direct burial as well.
It's not quite as flexible as LMR-400UF, but years of experience and
thousands of feet of coax makes me avoid the UF versions of the LMR
cables due to the characteristics of the jacket. I usually purchase 500
feet of BuryFlex(TM) at a time. Currently around 85 cents a foot in 500
foot spools and 78 cents in 1000 foot lots. I have no connection with
the company, just like their products and service.
When compared to the LMR cables it also has the advantage of not having
to make up rotator loops with the associated connectors. Typically I do
use it for rotator loops where the coax is large and/or relatively rigid.
I had 5, 28' pigtails at the top of the big tower. Most on here have
seen the photo, but: http://www.rogerhalstead.com/ham_files/Tower29.htm
the pigtails formed a three turn coil at the top of the tower.After 6 or
7 years (memory fails) the jacket on several had worn completely through
where it lay on the 45G top plate.
As the stuff is so flexible I decided to use the remaining that appeared
to be in good shape for jumpers in the station
BTW Using conventional stripping tools, I found the stuff to be a royal
PITA to strip. The old method of using a knife or box cutter worked
much better. The jacket wanted to bunch up under the stripper.
Also I noted the jacket had taken on a decided dull appearance. I had
made a couple jumpers and was in the process of installing another
connector when I notice the shield appeared to be a dull gray color. I
Stripped off several feet of jacket and found the shield to be pretty
much gone in several spots. one piece had a couple tiny splits, but the
jacket looked OK on the rest, but there were still bad spots in the
shield. At this point I pitched the whole 148 feet.
So I only use the UF versions if I really need the extra flexibility.
I discovered this "after" purchasing about 600 feet of LMR-600UF which
ended up going in the underground conduit where it's protected.
I should add that typically LMR-400 does not make good rotator loops.
It will work if you have enough room for a good size, 3 turn coil to use
for the rotator loop and install with care.
Another cable I do not like is CNT240. I found it to be just too
fragile. Small, solid center conductor which is easily broken. This is
one coax where you just score the jacket and bend it to separate it. The
braid over the shield is very fine and fragile. I've not tried the
LMR240, but assume it's probably similar, but assumptions are never safe.
I used it for a feed line to my 40 meter, half wave, center fed, sloper.
I had to replace the connectors every few months as they kept
breaking off. The wind causes a lot of movement in that feed line.
I've successfully used 8X for this feed line too, but it is now Davis
BuryFlex as is the feed line to the 75m sloping, fan dipole.
With shopping, I've found I could usually get the LMR-400, or Davis
BurtFlex(TM) for the same or within pennies of other coax
I now mainly use LMR 600. I bought it for VHF and up as well as for 160
where the lower IR loss can be important. However, I ended up using it
for almost everything due to the price break for quantity. However the
government wasn't purchasing a lot and I think I paid $1.20 a foot.
It's now around $1.80 a foot.
Look at all the suppliers and you may be pleasantly surprised.. or you
may not. Just depends on the market.
I edited and re edited this so I hope it still maintains continuity.
73
Roger (K8RI)
73, Jim K9YC
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