[TowerTalk] Fw: Coax, conduit and toroids
Marlon K. Schafer (509-982-2181)
ooe at odessaoffice.com
Thu Jun 28 08:34:41 PDT 2012
UG! I sure wish this list responded to the list vs. the sender.
Resending the below, to the right place this time....
----- Original Message -----
From: "Marlon K. Schafer (509-982-2181)" <ooe at odessaoffice.com>
To: "K8RI" <K8RI-on-TowerTalk at tm.net>
Sent: Thursday, June 28, 2012 8:19 AM
Subject: Re: [TowerTalk] Coax, conduit and toroids
> According to Timesmicrowave the LMR 600 cable has a bend radius of 6".
> I think LMR 400 is 2 or 3". I'd not be worried about using standard
> sweeps for the turns.
> Where it may get a bit tougher would be if you tried to use an LB to enter
> a building. Might need to look at a really big one or some other
> ----- Original Message -----
> From: "K8RI" <K8RI-on-TowerTalk at tm.net>
> To: <towertalk at contesting.com>
> Sent: Tuesday, June 26, 2012 5:57 PM
> Subject: Re: [TowerTalk] Coax, conduit and toroids
>> On 6/26/2012 8:30 PM, Rick Kiessig wrote:
>>> I'm interested in suggestions for how to best segment the coax running
>>> between my shack and tower-mounted antenna. I'm thinking of something
>>> this: (1) from shack to the base of the tower through conduit, tied to
>>> ground rod via lightning protector, (2) up the tower, (3) from the top
>>> the tower to the antenna, tied to #2 using a barrel connector and
>>> with weatherproof tape. The runs are fairly short, roughly 20m from the
>>> shack to the base of the tower and 10m up the tower. Have I missed
>> Grounding to the tower at the top and bottom is a good idea.
>>> I'm thinking of using LMR-600 for the first two segments (seems easier
>>> handle than Heliax),
>> It is, but unless you are running QRO and/or UHF it's quite a bit of
>>> and LMR-400UF for #3,
>> From personal experience with both LMR 400 and 600 UF the UF versions
>> do not stand up well out in the elements.
>> I use Davis BuryFlex(TM). It's almost as flexible as the UF cables and a
>> lot more durable.
>>> with UHF-style connectors for
>> UHF connectors are difficult to find for LMR-600. Davis was the only
>> company I found who would get them for me. They were a clamp type.
>> Using UHF connectors and UF cable I'm going to assume you are talking
>> about feeding a tribander or something similar.
>>> each. For my current setup, I ground the coax before it enters the
>>> The new tower will be right next to the house, so the tower ground and
>>> before-entering-the-shack ground will be the same thing.
>>> What should I do to help ensure that the inside of the conduit stays
>>> dry? Is
>>> applying some sort of weatherproof sealing compound to each end enough?
>> It's probably impossible to insure it'll stay dry, but a good start
>> would be http://www.rogerhalstead.com/ham_files/cablebox.htm
>> It's how I run the coax from both the shop and house to the tower. Check
>> the 3rd and 4th photos from the top and the bottom two rows. This
>> presents a good way to terminate the coax out of the weather as well as
>> entering the house without damaging concrete. I really don't worry
>> about the conduit staying dry inside unless I have connectors some where
>> inside the stuff. IIRC I included an explanation of what I did as well.
>>> I'm planning two coax runs and two control cable runs, in two separate
>>> conduits, coax in one, control in the other. What's a reasonable
>>> and turning radius for the conduit? The Times Microwave
>>> specifications/limits are one thing, but I also want to do what I can to
>>> ease/simplify the process of pulling the coax through the conduit once
>>> gets installed.
>> Use lots of cable pulling soap! Note the last photo in the above link.
>> I also used two sweep 45s in place of a single 90.
>> Size wise make the conduit large enough to hold at least twice as much
>> as you plan on putting in. That's for ease of pulling and unexpected
>> future events.
>> Also, don't forget to install a pull cable.
>>> Are there any precautions I should take with regard to running the coax
>>> control lines near existing electrical wiring for the house? I'm trying
>>> avoid proximity as much as I can, but I'm wondering how far I should go.
>> I'd keep them at least 3 to 5 feet apart if possible. Farther in very
>> dry conditions, but often we have to make do with what we have. I
>> actually have my control wiring and coax in the same conduits.
>>> Is it a good idea to create a coil of coax in or near the base of the
>>> run through ferrite toroids? I do this at the base of my vertical, but
>>> not sure if it's as useful for a horizontal antenna.
>> I have a one of these current chokes/baluns on each of my sloping
>> dipoles. On 75 I still had so much feedback that all the LEDs in the
>> shack would light by the time I reached a KW out let alone 1.5 KW. I
>> added a second choke in the 75 meter feed line at the tower and it
>> cleaned it up to where I can not detect any common mode voltage making
>> it back to the shack. If you need one, use one, if you don't then save
>> your money.
>>> I am planning to
>>> continue to use toroids at the shack end of the cable. Should I also run
>>> antenna and rotator control cables through toroids at both ends?
>> Roger (K8RI)
>> TowerTalk mailing list
>> TowerTalk at contesting.com
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