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@TheGallos.com>
> Subject: Re: [TowerTalk] Which feedline to use
> To: "Doug Rehman" <doug@k4ac.com>
> Cc: towertalk@contesting.com
> Message-ID: <787588292.20100908113527@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)
>
>
>
> ------------------------------
>
>
>
> ------------------------------
>
> Message: 4
> Date: Wed, 08 Sep 2010 11:22:36 -0700
> From: Grant Saviers <grants2@pacbell.net>
> Subject: Re: [TowerTalk] Which feedline to use
> To: towertalk@contesting.com
> Cc: Charlie Gallo <Charlie@TheGallos.com>
> Message-ID: <4C87D46C.8030708@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@karlquist.com>
> Subject: Re: [TowerTalk] Which feedline to use
> To: "Grant Saviers" <grants2@pacbell.net>
> Cc: towertalk@contesting.com, Charlie Gallo <charlie@thegallos.com>
> Message-ID:
> <72d436cff2b46595eec17f2b825a760a.squirrel@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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>
> End of TowerTalk Digest, Vol 93, Issue 26
> *****************************************
>
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