[TowerTalk] dustributors of coax and copper wire?

Wed Jan 27 23:19:24 PST 2010

Jim Brown wrote:
> On Wed, 27 Jan 2010 22:37:55 +0000 (UTC), ke2d at comcast.net wrote:
>
>   
>> I am in the midst of installing a new tower and need to start 
>> ordering materials.-  I need 2000ft of LMR400 style cable, 200ft 
>> of LMR600, 
>>     
>
> Before buying coax, I suggest that you study data sheets and 
> select cable that best meets your needs. I would NOT pay a premium 
> price for LMR cable 
They've changed. When I purchased 2000 feet (two seperate purchased of 
1000 ft each) the Times Wire cables, LMR 240, 400 and 600 were not 
expensive if you hunted.  I paid $1.29 and the LMR-600 is now up in the 
$150 range.  I think I posted something on these recently. 

 Yes, I purchased some CNT-240, but it was considerably more rigid than 
the LMR cable.  RG-8X (foil plus braid shield) was a bit less and a lot 
more flexible.

I try to stick with name brands, but I've not found Belden, which is 
often more expensive than Time Wire to be worth the extra money. Maybe 
I'm a bit anti-Belden after having to throw away nearly a 1000 feet of 
9913 after nature removed all the water proofing  from it at the top of 
the tower some years back and 15 minutes later I had water running out 
of a rig.  Back then LMR-400 was considerably cheaper than 9913, but 
Belden's price has come down  lot.

With RG-8X the quality varies widely. All I've used has been very 
flexible.  Some did not stand up well to the elements and some did. The 
RG-8X (foil&braid) from Davis (reminds me I need to order some more) is 
good, but I've had to give up using small cables CNT, LMR 240 and the 
RG-8X types from the remote antenna switches to the sloping dipoles as 
I'm now running the legal limit from band edge to edge and the voltages 
soar too high at the extremes on 75.  It's too bad as I really like the 
flexibility, light weight, and  low profile of those cables to the 
center fed, half wave slopers.

For prices check Davis, The RF Connection, and The wireman.  There are 
more suppliers who handle both house and brand names, but those are the 
only ones I can think of at present. For now I'm moving to Davis 
BuryFlex(TM) for rotator loops and to the feed points on the sloping 
dipoles.

> -- I recently measured the HF loss of LMR240 
> and found the published attenuation specs to be "optimistic." When 
> I have the opportunity, I'll do the same for their larger cables. 
> No debate that it's good cable, but my measurements show that it's 
> loss is only VERY slightly less than Belden's published data for 
> their RG8X, 9258, and The Wireman's RG8X, CQ118.  
>
> Authorities note that at HF, loss in coax is almost entirely due 
> to copper loss -- that is, plain ordinary Ohm's law, as modified 
> by skin effect. Dielectric loss kicks in at high VHF. If you're 
> buying coax for use on HF,
Operating all across 160, 75, and 40 with the legal limit I find some 
very high voltages which was my reason for moving to the LMR-600. That 
and I operate the 144 and 440 bands with about 230 feet of coax between 
the rig and antennas. As I had at least two runs to make I decided to 
standardize and use all the same cable for the runs fto the tower and 
from the base to the top of the tower.  The 160 half sloper is resonant 
at roughly 1/3 the distance above the bottom of the band, yet using the 
MFJ 989C tuner I was getting arcs near the band edges so I upgraded to 
the Palstar AT5K which is built like a tank and has very high voltage 
ratings on the capacitors.
>  simply study the Belden catalog and 
> that of other mfrs and buy the coax that has the lowest DC 
> resistance of the center conductor and shield combined from a 
> manufacturer that you trust. Commscope 3227 is great if you can 
> find it, probably better than LMR400. 
>
>   
>> probably 1000ft or so of dipole wire
>>     
>
> I have a lot of wire antennas in tall trees. I buy #10 or #12 THHN 
> (house wire) from Lowe's or Home Depot. If you're hanging in trees 
> or on a mountaintop, use #8 or #10. 
>
>   
>> insulators
>>     
>
> I like egg insulators from RF Connection. 
>
>   
>> center feed baluns or insulators
>>     
>
> Do NOT buy a commercial "balun" -- roll your own FAR better than 
> you can buy following my Cookbook. 
>
> http://audiosystemsgroup.com/RFI-Ham.pdf 
>
> For center insulators, I like the one with a coax connector 
> attached that The Wireman sells for about $10. The Alpha Delta is 
> a lot more expensive, but seems solid. Some like the Budwig, but I 
> find the attachments not sufficiently robust for high dipoles in 
> trees. 
>
>   
>> Also 200ft or so of HD rotor cable.
>>     
>
> This may sound crazy, but for the 250 ft run to my tower, I used 
> two parallel runs of 14-3 house wire from Lowe's (each is four 
> conductors, counting the "ground"). As it turns out, you can buy 
> this stuff cheaper than you can buy 6-conductors of #18 in a 
> jacket. To go up the tower (120 ft), I found a shorter length of 
> multi-conductor in a jacket and spliced it at the base. 
>
>   
>> Has anyone used the newer Belden RF400 series cable?-  Or the 
>> knockoff brands of LMR400 equivalent? 
>>     
>
> It all comes down to who you trust. I trust Belden, Commscope, and 
> Times to make very good cable (although I don't trust Times' 
> published specs for attenuation).
>   
Belden and some of the knockoff brands are the only ones that have given 
me problems with one exception. The cable was good, but the jacket of 
the LMR UF versions is a rubber like material.  Those cables are truly 
flexible, but the jacket will only last 5 to 10 years. Even though they 
are a bit more flexible than BuryFlex (TM) I've gone to BuryFlex because 
of it being more rugged for the rotator loops and has stood up well from 
the tower to the sloping dipoles.  You may have gotten a bad batch of 
Time Wire cable, but every piece I've tested has been right on spec 
within the tolerance of my equipment.
>   
>> There are two vendors on eBay selling 1000ft rolls of LMR400 
>> equivalent cable for $325/1000ft roll, which so far seems hard to
>> beat. 
>>     
>
> Everything depends on quality. There are LOTS of WHORES (brokers) 
> in the cable biz, most of whom don't have a clue about 
> engineering.  
>
>   
I'm very Leary about knockoff brands and I won't purchase coax off e-bay 
unless it's a known distributor selling brand names.

73

Roger (K8RI)
> 73,
>
> Jim K9YC
>
>
>   
> ------------------------------------------------------------------------
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>   