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Catalina/Capri 25/250 Sailor's Forums

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RG-8x Coax

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Deltarat
1st Mate

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USA
69 Posts

Initially Posted - 03/19/2009 : 23:21:06

The antenna COAX in my mast is old and cracking and desparately needs to be replaced. I've been told the best stuff to use is RG-8x or Rg-8u what would be a good price for this stuff. I only need 30' I've checked some of the electrical warehouses for this, no go, I've found some on e-bay, but don't know if it is a good price.

Any advice would be helpful, thanks.

Some mistakes are just too fun to only do once.
1982 C25 #3276
Owl Harbor
Isleton, CA

Edited by - on

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 03/19/2009 : 23:53:47

Check retail prices at WM, Defender, and the like on line for a baseline. I don't remember what I went with last year, but it was the largest diameter (a little more weight aloft) and lowest loss of the three I was considering. There are some radio people here who will probably chime in soon. Also, read this:

http://www.westmarine.com/webapp/wcs/stores/servlet/westadvisor/10001/-1/10001/CoaxialCable.htm

Edited by - Dave5041 on 03/19/2009 23:54:12

johnsonp
Admiral

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USA
606 Posts

Response Posted - 03/20/2009 : 00:11:17

This where I used to get my cable.
http://www.metro-electronics.com/

paulj

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KD4AO
Navigator

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USA
202 Posts

Response Posted - 03/20/2009 : 05:40:36

I would get it from a Ham Radio store. Not sure what is in Sacramento but mail order is usually very reliable. Try http://www.hamradio.com/, they have a store in Oakland.

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 03/20/2009 : 11:47:43

I'm pretty sure I ended up using RG 8x when I re-did my coax up the mast last year. Make sure you get more than you need. The last thing you want is to have to make a splice in your coax. You're also going to strain the parts of the cable that go into & out of the mast, so you want to be able to cut away those sections leaving only good cable behind.

Wear gloves when you've got your hands inside the mast, the extrusions are sharp, and there are lots of little burrs to bloody your knuckles.

Put grommets in where the cable enters & exits the mast to reduce wear & strain on the cable as well as reduce water intrusion.

Make sure to make drip loops, especially at the top so rainwater won't run down either into your mast or the antenna base via the cable. It's not so critical at the base of the mast as long as you...

Waterproof all your connections. I used self fusing silicone tape on mine. Adhesive shrink wrap would probably be a better solution if you can find some large enough to go around the PL 259 connectors.

Shakespeare makes some nice gold plated no-solder PL 259 connectors, they're a bit fiddly, but you'll figure it out by the second one. Maybe get an extra to practice with.

Also make sure you leave behind an extra pull string when you pull your new cable.

While you're working on the top of the mast, check your lights as well. Might as well fix them while you're there instead of having to drop the mast again to do so.

Edited by - delliottg on 03/20/2009 14:30:40

KD4AO
Navigator

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USA
202 Posts

Response Posted - 03/20/2009 : 14:10:44

The following is from Catalina Fleet 21 http://www.catfleet21.org/rigging/June.htm and shows that RG-8U is nearly 1/2" in diameter while RG-8X (Mini 8) is only 1/4". The difference in loss at VHF is nearly negligible and the difficulty in dealing with the larger and stiffer RG-8U vs RG-8X makes the Mini 8 the best choice for a boat VHF installation. Price about $.59/ft.

Table COAX Cable Size VS. Signal Loss

Cable__Diameter___Loss___Length Per
Type___(Inches)___100'___3 dB Loss

RG-58___.195_____6.1 dB___ 49'
RG-8X___.245_____4.5 dB___ 66'
RG-8U___.410_____2.7 dB___ 111'

Choosing the proper coax size

RG-8X, RG-8U, RG-213U, or Belden 9913 are all good VHF coax choices. RG-58 is too light for anything but the shortest runs. Marine VHF requires 50-52 ohms impedance coax, so don't try using cheap TV 72 ohm coax or CB coax. It is a good practice to check the coax with an ohm meter before installing connectors. After installation, check again for the same reading. (Note: Some antennas are DC grounded and will indicate a short circuit whentested with an ohm meter. Antennas which do not use DC grounding generally read as an open circuit on an ohm meter).

Edited by - KD4AO on 03/20/2009 14:43:31

Deltarat
1st Mate

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USA
69 Posts

Response Posted - 03/22/2009 : 01:15:57

Thanks for all of the great input, I was able to find RG-8x at Metro Electronics here in Sacramento for .69 per foot, along with PL259 connectors and adapters for the smaller cable. I ran the new cable today and soldered on the connector for the antenna today, but will wait til the mast is stepped to solder the other connector in place that way I know exactly how much to cut. Now all I'm waiting for is the new antenna, Masthead light and new steaming/deck light.
Has anyone added a 4th circuit to their mast for a deck light? Did you have to drill a hole in the liner to run the new wire or is there a trick to feeding the wire between the deck and liner? I tried a snake today, but there doesn't seem to be any clearance.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/22/2009 : 10:35:05

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Deltarat
 Did you have to drill a hole in the liner to run the new wire or is there a trick to feeding the wire between the deck and liner? I tried a snake today, but there doesn't seem to be any clearance.
<hr height="1" noshade id="quote"></blockquote id="quote">

If your boat is like mine, you will not be able to run new wire between the deck and liner.

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Sloop Smitten
Master Marine Consultant

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USA
1181 Posts

Response Posted - 03/24/2009 : 15:05:51

According to Don Casey RG-8x should not be used in runs over 25'.
Read more:
[url="http://www.boatus.com/boattech/antennas.htm"]Don Casey on maximizing gain on a VHF radio[/url]

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jbkayaker
Captain

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USA
299 Posts

Response Posted - 03/25/2009 : 12:46:22

I would like to use a female connector on the end of RG-8x cable to make an antenna wire extension cable. The proper female connector would mate with a PL-259 male connector. Only I cannot find such an item at West Marine or Defender or anyplace else. The nearest I can find is an double female adapter that accepts two PL-259's. Does anyone know where I can find a female connector to put on the end of a RG-8x cable ?

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 03/25/2009 : 12:57:08

I did a bit of searching around, and I'm not sure they make one, I think it's standard to just used a double ended female to make your connections. Seal it well with some self-fusing silicone tape, or some big adhesive lined shrink wrap and you should be good to go.

Edited by - on

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