Users may not create topics, posts, or private messages containing or relating to the following material (especially pertaining to Motorola copyrighted software, unless you want Motorola to come along and shut this site down):

  • Listing for sale or trade of, or links to sites offering for sale or trade of, or giving away, Radio
    Service Software (RSS) or Customer Programming Software (CPS)
  • Profanity, pornography, defamation, or slanderous remarks directed towards any individual or entity
  • Commercial advertising (except in the Batboard Vendors forum, as approved by the Admin/Mod Staff)
  • Any other items which may be deemed as offensive

If any topics, posts, or private messages containing or relating to the aforementioned material are brought to the attention of the Admin/Mod Staff, they will be deleted.

Additional FAQ items appear here in Forum Rules. Please review them for posting guidelines and further clarification.

Coax recommendation portable UHF base station

The General forum is where users can discuss any topic regarding Motorola communications equipment - hardware, software, etc. There are also several focused forums on this board, so please take the time to ensure that your questions doesn't fall into one of those categories before posting here!

Moderator: Queue Moderator

RadioSouth
Batboard $upporter
Posts: 2858
Joined: Mon Sep 03, 2001 4:00 pm

Coax recommendation portable UHF base station

Postby RadioSouth » Tue Sep 05, 2017 9:10 am

Hi guys,
Looking for coax recommendation. Setting up a portable VHF/UHF base station with Diamond X-30 on collapsible tripod. Coax run would be 50' and I'm looking for something with a stranded center conductor to minimize breakage. RG58 looks like a 5dB loss, RG8X is a little better. Anything up to the diameter of RG-8/U would be good as long as it's flexible and has a stranded center conductor.

User avatar
W3AXL
Posts: 89
Joined: Fri Sep 04, 2015 9:02 am
What radios do you own?: an unhealthy amount of them

Re: Coax recommendation portable UHF base station

Postby W3AXL » Tue Sep 05, 2017 11:37 am

LMR240 ultraflex wouldn't be a bad idea. If you wanted lower loss you could bump up to LMR400 UF. 240 is the size of RG8x and 400 is the size of RG8.

If I wanted portability and low loss I'd put my money with LMR240 UF. At 50' you'd have 3dB of loss on 440. LMR400UF would be ~1.5dB loss at 440.

User avatar
Astro Spectra
Posts: 603
Joined: Sat Sep 22, 2001 4:00 pm

Re: Coax recommendation portable UHF base station

Postby Astro Spectra » Tue Sep 05, 2017 11:56 am

Mechanical ruggedness is much more important than loss for a portable set up. Everything is going to get banged and slammed, so a solid cable is critical. I'd use RG-213.

The X30 is not super rugged but OK. I've used them for transportable systems but they're quite narrow band. I had to use a network analyser to adjust the length of the VHF element to cover the 136-144 MHz range with acceptable return loss. UHF will not work out of the amateur band without major surgery.

Best add a length of woven polyester expanding braid cable protection (hold in place with cable ties) over the coax where it enters the X30 mount tube to avoid wear and tear on the coax outer.

It's a dog assembling the mounting so I use a short length of coax with a PL-259 permanently attached to the antenna (tighten with vice grips) and hanging out with a type N female with a plastic cap. The avoids over using the single bolt that holds the mount tube in place as the thread in the muck metal boss casting is fragile. You may want to Araldite the whole tube in place on the antenna boss or at least Locktite the bolt to stop thing working lose.

With these precautions I've had unmanned crossband relays stay in place using the X30 on a guyed thick walled alloy tube 10' mast in 100mph plus winds on hilltop sites.

Last but not least throw some 1" ratchet strap tie downs in your kit. I pack three to use as mast guys but you can always wrap one around the mast section when fastening to something like a porch upright or sign post.

Jim202
Posts: 3476
Joined: Sun Sep 09, 2001 4:00 pm

Re: Coax recommendation portable UHF base station

Postby Jim202 » Sun Nov 19, 2017 5:19 am

The big issue with any coax cable is the interface between the cable and the coax connector. Using regular type N or PL-259 connectors is that your relying on just the shied to secure the connector to the cable. It is not very strong and won't hold up long to much movement or twisting.

Wedge lock type connectors is a much more secure connection. But they cost and delivery is not that good. Most places don't stock them.

So your next choice is to go with a crimp shell and solder the center pin. These crimp connectors seem to stand up far better than just trying to rely on pinching the shield or soldering the shield to the shell of a PL-259 connector. Draw back is that you need the crimp tool.

Jim


Return to “General Motorola Solutions & Legacy Radio Discussion”

Who is online

Users browsing this forum: Bing [Bot] and 6 guests