Re: [TowerTalk] BELDEN 9913 COAX PROBLEMS?
With respect to the thread on Belden 9913 Flex tech/engrg hold and the
validity of use of such cable, let me offer you the following from a ham of
39 years and as a supplier of cable & cable design engineering. I'll try
to be as short as possible.
(1). Belden is not the panacea of cables that so many people advocate and
get sucked into. They've had their share of the problems, and we all pay for
the name. Equal performance is out there for a lower price.
(2) Migration of center conductors can be a problem in near air dieletrics
like 9913 but if handled properly usually does not present any issues. Ref.
foam dielectrics, the problem is almost non-existant w/QUALITY built cable if
bending is within its rated bend radius, adding a couple of inches to be safe
(the low loss cables mentioned herein are all .403" prox OD's and in turn
their bend radius, rated is about 2"; but, add a little for safety. 9913
std, in my oinion, safe at about 5" and 9913F is about 3.5". Looking at
these cables on a network analyzer as you bend them within limits is not
going to result in a concern.
(3) The "engineering hold" on Belden 9913F is somewhat an anomaly and IS a
major problem. Bury-Flex Tm and CQ 4XL FLexi have low loss cores of VP
efficient foamed diel. and stranded ctr. condctrs., (NOTE): which are
excellent replacements for 9913, or 9913F, at lower cost.
(4) Many hams desire the extra fractions of dB in the HF spectrum that 9913,
LMR, Bury--Flex (Tm and design of Davis RF Co.) and The Wireman CQ Flexi 4 XL
# 102, low loss cables provide. Greater advantages ensue with these cables
at VHF and above, obviously (varies with type and freq).
I seem to see a "thread" in the use of these at HF, just like we have all
seen the past thread on 9913 (std) as being THE low loss cable for many
years. Then, after the design of my Bury-Flex cable , a similar cable, 9913F
comes along; however it does not have the durability, high density and high
durometer of our Polyethylene jacketed cable. It uses foam, as does ours, a
stranded center conductor, as does ours...all for flexibility, but the next
step in Belden's mind is, for flexibility sake mind you, a TPR jacket. Same
story for LMR UltraFlex and June l999 release of Harbour Cable's "HPF" cable,
with all the same specs as LMR, not to mention their VP of Marketing who came
from Times Cable (LMR mfr). Interesting, HI.
In part, agreeing with a previous TTalk writer, the question is, who
needs a really flexible cable (little more flex with TPR than PE)) when you
can , for less money and (only) tenths of a dB less loss through VHF, use
regular 9913, or Bury-Flex Tm, or LMR400 (std, vs. LMR 400 Ultra Flex), to
the rotator, AND to the antenna in the case of all but the 9913 (std.).
(5) In the case of 9913 std., splice in a flexiblle rotator loop like RG213
(only if you feel that adding 30% more of the 9913 loop than for a cable like
RG213 that you don't have a way to controlling excessive mechanical influence
of high winds, etc).
Here's the rub: in my many years as a ham and selling hams and
commercial RF folk, to "splice in" even at HF or up to 300 Mhz. is looked
on as almost a "sin". Part of this outlook is due to the influence of
"famous old wives tales". I receive emails, "Is it true that I will lose 1
dB or > if I connectorize (2 connects) and a barrel at 30 MHz (or even at 300
Here's my opinion based on research and discussion with connector engineers:
Every TYPE of connector has a given MUF. Most of the quality connectors are
similar in MUF, by type (UHF, N, SMA, etc). Most quality connectors will not
exceed .2 dB insertion loss at MUF, thus, if a UHF is good to 300 MHz MUF,
then at 150 MHz it will attenuate approximately half of that .2 dB seen at
MUF. So, at 30 MHz it's much less. Go above 300 MHz, use good N's, TNC's
etc. N's and TNC's can have only .13- .15 dB insertion loss at MUF (high end
microwave) but PLEASE, don't run out and use them for HF-300 MHz vs. UHF
due to the "lower" insertion loss. HI.
(6) Find the suppliers that will give you their experienced knowledge and
guidance by asking Tower Talkers who they use and respect. These companies
are few in the ham market and they literally "bend over backwards" to give
you the straight scoop and quality product. If there is a company who
won't give you the EXTRA time of day, or acts like it is a bother to answer
your question, but, they will give you a lower price on the standard sold
cables, opt not to deal with them.
Give the reputable companies the credit that they are ethical, knowledgeable
and there FOR YOU. Pay the few cents more (in some cases) for their higher
quality product, not that you are paying anything for their knowledge and
PS It gaulls me that a company was/is still (?) out there selling
"non-contaminating" direct burial RG213. It does not, and chemically can
not, exist and meet the jacket specs of C-17 Mil Type or Mil Spec QPL RG 213.
If it does, it is NOT a buriable cable. For more on this see
www.davisRF.com, choose "Amateur Radio" . Note: The term "connectorize"
is a Davis RF word, not yet recognized by Websters, HI !!!
If you want a "shorter" (I promise) thread on Heliax vs LMR pro's/cons, let
Cheer, Steve Davis, K1PEK DAVIS RF Co.
DAVIS RF Co., commercial wire and cable, custom cable design. Discounts to
hams. Heliax, LMR, RFS, Belden, BURY-FLEX Tm. Various aerial wiring;
transmission lines, insulators, baluns, RF connectors and Dacron rope.
www.davisRF.com . 1-800-328-4773, (For all RF hardline related items, please
ask for Steve Davis) Thank you!
"The Triad": Davis RF Co.; Orion Wire Corp.; and The Wire Man, Inc.:
Variegated expertise; resources and buying power yielding numerous quality
products at highly competitive pricing.
a message dated 8/27/99 10:01:36 PM Eastern Daylight Time, firstname.lastname@example.org
<< From: email@example.com
To: firstname.lastname@example.org (Donald E. Stiles), email@example.com
Personally, i don't understand why anyone would buy flexible foam
dielectric cable to begin with. For years and years, we've known that if you
bend the stuff, the center conductor miagrates. Is it worth it for a lousey
1/10th or 2/10th db. less loss? Of course not!
Why would anyone want Belden or anyone elses 9913? The loss in it is
hardly any better than RG-213.If you don't think RG-213 is the way to go,
then buy some really good stuff. Look at the LMR series cables, or better
yet, hardline! Money spent here stays on the job many times over.
So, if you feel you got burned, stop whinning and send the cable back and
get your money back. Or suffer the loss and move on.
Sooner or later we get burned on something. Everyone gets a turn in the
barrel. What do you think they should do? Pay you for your inconvenience?
73 de Roy Lincoln WA4DOU Elm City, N.C.
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