Who said rotor loops HAVE to have a stranded center conductor? In fact,
routed properly, I can see where a solid conductor cable might have
certain advantages over stranded center cables... especially when the
feed point isn't on/near the mast...
LMR-xxx - Yep... the numbers on the cable are typically the cable size
in 1/1000ths of an inch.... 240 = .240", 400 =.400", 1200 = 1.200",
etc. At some point (>600?) it goes to a copper tube for center
conductor. So, yeah... a 1.2" cable stock WOULD be a little more work
to route. <smile>
It all depends on your willingness to trade off difficulty in ONE-TIME
effort for installation versus decreased loss as diameter increases.....
discounting the added cost of cable stock, connectors, and tooling of
course. I lean towards the over-engineering side of the house...
always, $$ permitting.
The gray PVC to which you refer is electrical conduit (most likely) and
is much more resistant to UV than white (which should NEVER be used in
full sun unless you don't mind it disintegrating in a few years). The
gray ALSO uses large radius fittings which assists in pulling wire.
ALWAYS use a conduit size rated for the wire you intend to pull....
Generally, I use a conduit that is TWICE the size required for the
wire/bundle I am pulling to make room for a possible subsequent pull.
But I likely wouldn't do that with feed lines... PS - ALL conduit gets
wet underground EVENTUALLY.... NOT really a hard and FAST TRUTH, BUT
YOU should ENGINEER AS IF IT WERE. Must plan for how to dry the
conduit. Almost any cable jacket will eat water if it sits in standing
water long enough.
Yes.... Look at the spec sheets. There are a number of parts for each
size... Availability is subject to vendor selection. I use -DB inside
and outside. The weight diff is insignificant to me, and the tools
clean up fast. A little extra time on each termination is a fair trade
off for superior longevity.
73,
______________________
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389
On 8/24/2017 12:09 PM, Jim Thomson wrote:
> Date: Wed, 23 Aug 2017 15:41:10 -0500
> From: Clay Autery <cautery@montac.com>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Crappy LMR600
>
> <Curious as to why y'all don't use the LMR-400-DB or LMR-xxx-DB cable
> <INTENDED for exterior use?
>
> ## useless for rotor loops, since both use a solid center conductor, esp
> with 600-UF.
>
> I have aprx 90-100 ft of T-com LMR-600UF.... which has 27 strands in the
> middle instead of the usual 7 strands in the normal 600-UF version. Far
> more flexible,
> like spagetti compared to 213-U. I was going to use it for going up the
> side of the crank up
> tower... but knew of the problems using it outdoors.
> The jacket on the UF is like pure soft rubber. Prone to nicks + UV +
> critters. I thought
> of using split loom, but only find it locally in 10 ft lengths. Trying to
> get 90-100 ft of 600-UF
> inside a 100 ft continuous length of split loom would not be fun either.
> Plan B was to wrap the entire 90-100 ft with scotch 33 or 88 tape. I believe
> that would
> solve 99% of the issues with outdoor use. That should be good enough for
> going up the side
> of a crank up, and or used for rotor loops. But typ rotor loops are short
> anyway, so plane
> 213-U..or buryflex would be a more practical option.
>
> ## I have a 125 ft reel of regular LMR-1200DB to go from basement to base
> of tower, but that
> stuff is an absolute bitch to work with. About as rigid as an aluminum
> baseball bat, and large OD too,
> like 1.2 inchs. .5 inch heliax or LMR-600DB would be easier to work
> with..and I may well go that route.
> I may well install it inside grey pvc pipe, since I can get that locally at
> any home dept, in every ID from
> .5 inch up to 2 inch. Each 10 ft section is flared at one end, so they can
> easily be glued together. Then just
> lay it next to the house..which is all bark mulch, like 6 ft out from
> house..and aprx 40 ft long. Maybe another
> 20 ft to get to base of tower.
>
> ## BTW, Times Microwave tells me that they also make all of the various
> LMR 400-500-600-900-1200
> cables in a NON DB version. Same outer jacket, just NO grease in the braid.
> Price is the same. Funny
> thing is, I have never seen the non DB version listed on any site ever.
>
> Jim VE7RF
>
> _______________________________________________
>
>
>
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