[TowerTalk] Which feedline to use + 9913F7 Resp. DAVIS RF CO. ^^^

Wed Sep 8 12:25:35 PDT 2010

  Hi, I have to agree with Grant, we do a lot of cables for a Nycoil assembly house and never have we supplied hard line.  The RF cable needs only to be low loss coax due to the short length vs. acceptable attenuation for the application.   There are also MANY other cables , wires, in there...picture a 100 ft. Nycoil (the red conduit you see, slinky, around the telescoping mast) being laid FLAT in a channel type metal "guide",  and the installers hoping that the retainers don't let go or it is actually dangerous (it's coiled "memory")... has to be laid flat for up to 100 ft. in order to get the cables pulled thru.   

Ref the original question,  you can just about use any coax, hard line, Bury-Flex Tm, LMR -400 for a rotar loop...just judge the flexibility, turn radius, height to antenna, etc.  and figure out the right length which will accomdate the cable choice.   I don't suggest LMR-400 UF if you want it to last for many years.  The TPE outer jacket of 400 UF is not great in UV, but the std. 400 (as does Bury-FLex) uses a PE outer jacket which will hold up for years.  If you feel you need 
max. flex, contact us for Belden 9913F7, a great cable that uses their Belflex Tm outer jacket which is highly UV resistant for a blend of PVC, double shielded for 100% shield coverage (and NOT to be confused with their other 9913 cable).

For the coil around the crank-up tower (and even for the rotar loop) I recommend  Bury-Flex, TM (Davis RF). It works extremely well for crank ups, doesn't bind, and it is less expensive vs. LMR-400.  Available at most of our dealers. 

Cheers, Steve  K1PEK
DAVIS RF Co.,  Div. of Orion Wire Co., Inc.

Wire, Cable, RF Connectors and wire aerial parts.  

LMR, Heliax, Eupen

Commercial / Military

Custom Cable Design

tel:  978-369-1738     Fax:  978-369-3484
www.DavisRF.com

> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Wed, 8 Sep 2010 11:35:27 -0400
> From: Charlie Gallo <Charlie at TheGallos.com>
> Subject: Re: [TowerTalk] Which feedline to use
> To: "Doug Rehman" <doug at k4ac.com>
> Cc: towertalk at contesting.com
> Message-ID: <787588292.20100908113527 at TheGallos.com>
> Content-Type: text/plain; charset=us-ascii
> 
> 
> On 9/8/2010 Doug Rehman wrote:
> 
> ...snip... The
>> antennas have been used in contesting, including VHF/UHF, so they've seen a
>> lot of rotation. The rotor loop is fairly large, sticking out from the tower
>> about 2'. LMR-400 is stiff enough, especially when multiple runs are
>> bundled, that the rotor loop doesn't hang. So far, no problems.
> 
> ...snip...
> 
> Let's face it, you know those TV remote trucks you see? (here in NYC, all the time) - what do they use on that mast?  Hardline!  The trick is, is you look, is it makes a BUNCH (a BIG bunch) of turns around the mast so that the wire doesn't move all that much each time the antenna is raised/lowered/turns (That and the fact that they are willing to replace the cable more often than most of us)
> 
> -- 
> 73 de KG2V - Charles Gallo
> Quality Custom Machine-shop work for the radio amateur (sm)
> 
> 
> 
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> 
> 
> ------------------------------
> 
> Message: 4
> Date: Wed, 08 Sep 2010 11:22:36 -0700
> From: Grant Saviers <grants2 at pacbell.net>
> Subject: Re: [TowerTalk] Which feedline to use
> To: towertalk at contesting.com
> Cc: Charlie Gallo <Charlie at TheGallos.com>
> Message-ID: <4C87D46C.8030708 at pacbell.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> I've just helped recommission one of the former KABC vans for a virtual 
> classrom, satellite link, 802.11, 2m, 70cm, & GMRS radios, etc. for the 
> upcoming ARLISS rocket launches  (see  aeropac dot org)  There was no 
> hardline anywhere in this van.  What may look like hardline is a coil of 
> Nycoil nylon 1.25" id coiled air hose which is used as a flexible 
> conduit.  There were 19 cables inside the old Nycoil and they are 
> impossible to remove.  I had to buy new Nycoil ($1k+ for 70') and pull 
> new wires, which was a struggle and uses some tricks.  If there are 
> uwaves or UHF the amps/preamps were at the top of the mast, a 40 footer 
> in our case.
> 
> The Wil-Burt local guy was helpful.  The up/down action of the mast 
> tends to twist the wires inside.  They don't recommend any solid 
> conductor cables.  The cable load for the new conduit was 2 x Buryflex, 
> 2 x RG8X, 2 x CAT5e, DC power, AC power, pan/tilt control head 8 
> conductor.  Lots of TFE pulling grease and 5 people got them pulled.  We 
> tied the Nycoil every 5' to a strong fence, so it was pretty straight, 
> otherwise it is impossible to pull through the loops.
> 
> Grant
> KZ1W
> 
> 
> Charlie Gallo wrote:
>> 
>> ...snip...
>> 
>> Let's face it, you know those TV remote trucks you see? (here in NYC, all the time) - what do they use on that mast?  Hardline!  The trick is, is you look, is it makes a BUNCH (a BIG bunch) of turns around the mast so that the wire doesn't move all that much each time the antenna is raised/lowered/turns (That and the fact that they are willing to replace the cable more often than most of us)
>> 
>> 
> 
> 
> ------------------------------
> 
> Message: 5
> Date: Wed, 8 Sep 2010 12:00:23 -0700
> From: "Rick Karlquist" <richard at karlquist.com>
> Subject: Re: [TowerTalk] Which feedline to use
> To: "Grant Saviers" <grants2 at pacbell.net>
> Cc: towertalk at contesting.com, Charlie Gallo <charlie at thegallos.com>
> Message-ID:
> 	<72d436cff2b46595eec17f2b825a760a.squirrel at webmail.sonic.net>
> Content-Type: text/plain;charset=iso-8859-1
> 
> Grant Saviers wrote:
>> The Wil-Burt local guy was helpful.  The up/down action of the mast
>> tends to twist the wires inside.  They don't recommend any solid
>> conductor cables.  The cable load for the new conduit was 2 x Buryflex,
>> 2 x RG8X, 2 x CAT5e, DC power, AC power, pan/tilt control head 8
>> conductor.  Lots of TFE pulling grease and 5 people got them pulled.  We
>> tied the Nycoil every 5' to a strong fence, so it was pretty straight,
>> otherwise it is impossible to pull through the loops.
>> 
>> Grant
>> KZ1W
> 
> Did you pull the whole bundle through as a unit or pull the cables
> through one at a time?  I like your fence idea.  I should have
> done that when I pulled wires through 200 feet of plastic flexible
> conduit.  Is TFE pulling grease different than the ordinary stuff
> they sell at hardware stores?  Where do you get it?  Is it a lot
> better?
> 
> One time I got the "bright" idea to pull RG58 coax into cheap
> poly drip irrigation tubing to make it "critter" proof.
> After spending hours with various techniques, I gave up.
> The stuff wants to curl up and kink, and it is amazing the amount of
> friction that even 100 feet of it has.
> 
> Rick N6RK
> 
> 
> 
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