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[TowerTalk] Low Loss Cables and Problems/Uses

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Subject: [TowerTalk] Low Loss Cables and Problems/Uses
From: (
Date: Sat, 28 Aug 1999 03:01:51 EDT
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, 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 
me know.
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. .  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, 

<< From:
 To: (Donald E. Stiles),
 Hi All,
   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?
 Get real! 
   73 de Roy Lincoln WA4DOU Elm City, N.C. 

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