This table shows results for the 2Meter ham band, which is very close
to the vhf marine band.
There are many other options, but most are rare so very much more
expensive, and connectors harder to find.
This data came from
http://www.antennex.com/preview/Fold...4/newstat1.htm

Note:
3dB cuts the power [or received signal] in half.

Also: mouser.com & graybar.com are places that I frequent for this
sort of thing, competative prices and market rate shipping.
tom
=-==


Cable Insertion Loss at 150 MHz, 100-Foot (30.5 m) Length Cable Type
Cable Loss Comments

RG-58C/U 6.6 dB Very short cable runs, Test Cables
RG-58U 6.0 dB Very short cable runs, Test Cables
RG-8U 3.2 dB OK up to 30 feet (9.15 m)
RG-8U FOAM 2.2 dB OK up to 45 feet (13.7 m)
9913 (Belden) 1.7 dB Recommended for all installations
..5 Inch "Hard Line" 1.0 dB Excellent but may be cost prohibitive



cavelamb himself wrote:
I'm adding a VHF radio to my sailboat and would like to ask for details
about the antenna cable.

RG-58 is recommended, but the losses in the cable seem staggering!

Is there a better cable for antenna connections???

Richard

Capri 18
Spirit

RG8 [not 6] is MUCH bigger in diameter than RG58. RG58 is also much
mor flexable.
But I wouldn't recommend it for this length, unless a very sharp bend
is absolutely necessary.
tom
=-==

Larry wrote:
cavelamb himself wrote in news:4hXdh.7885
:

RG-58 is recommended, but the losses in the cable seem staggering!

Is there a better cable for antenna connections???

Richard

Capri 18


"Staggering"? RG-6 would be much better at about the same price. It's
only a hair bigger diameter, available at any marine store selling
electronics. With a 40' run of RG-6 you still get 75% efficiency.

If you must:
http://shop.electro-comm.com/ac/Prod...=19707&view=24
LMR-1700-DB, double-shielded, direct burial, waterPROOF will give you
97.9% at 156.8 for 40' but noone will notice it on the air, only in your
pocket book at $10/ft plus some pretty impressive connectors. Way
overkill. It's 1 1/4" diameter...not good. RG-6 is better.

The Icom M802 on Lionheart has about 70' of RG-6 to a Metz Manta 6 at
55'. Savannah is 100 miles from here. I hear them all the time and I
know they can hear me because they called me...(c;



Larry
--
If we eliminate religion, will they stop murdering each other?

LMR cable has polyethylene outer jacket and foam insulator so you have to be
very careful about sealing up the connectors. The LMR-DB cable is filled
with an inert gel to prevent water migration and is guaranteed for 10,
years. I used LMR-400DB with SMA connectors which are about the same
diameter as the cable and slip a piece of adhesive lined shrink tubing over
the joint.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"cavelamb himself" wrote in message
ink.net...
Jack Erbes wrote:
Glenn Ashmore wrote:

If you are going to the masthead the ultimate in low loss would be
LMR-400 or 400UF. Slightly lighter weight than RG-8 with about half the
loss at 157mhz.

LMR type coax is real popular with the wifi folks but I don't know why
it has not been better accepted in marine VHF. It is lighter weight and
handles bends with less loss than the regularly used coax.


What glen said! LMR (Times Microwave) has the LMR series coaxial cable
in a range of sizes that will replace RG-58, RG-8, or any other commonly
used coax. And it outperforms all of the "old standards" by the specs
and in my experience.

http://www.timesmicrowave.com/wireless/index.shtml

Jack

Will check it out.

The recomendation from BoatUS was PVC jacket and tinned internal
conductor (ratehr than bare copper). And to avoid foam filled cables.
http://www.boatus.com/boattech/antennas.htm

So?
PVC jacket, tinned stranded internal conductor, and..
What kind of insulation? Air?


We do occasionally swim in the salt...

Richard

Well,
It's about time. I was starting to wonder why you had the VHF
tied into the broadband.
Matt

Larry wrote:
OOPS...belay my last!....RG-8X

I been spending way too much time fooling with wifi crap....(c;

sorry


INCOMING! HEAD FOR THE SHELTER!!

It should have read:


"Staggering"? RG-8X would be much better at about the same price.

It's

only a hair bigger diameter, available at any marine store selling
electronics. With a 40' run of RG-8X you still get 75% efficiency.

If you must:
http://shop.electro-comm.com/ac/Prod...=19707&view=24
LMR-1700-DB, double-shielded, direct burial, waterPROOF will give you
97.9% at 156.8 for 40' but noone will notice it on the air, only in

your

pocket book at $10/ft plus some pretty impressive connectors. Way
overkill. It's 1 1/4" diameter...not good. RG-6 is better.

The Icom M802 on Lionheart has about 70' of RG-8X to a Metz Manta 6 at
55'. Savannah is 100 miles from here. I hear them all the time and I
know they can hear me because they called me...(c;






Larry

"tlindly" wrote
RG8 [not 6] is MUCH bigger in diameter than RG58. RG58 is also much
mor flexable.
But I wouldn't recommend it for this length, unless a very sharp bend
is absolutely necessary.
tom



Besides that, if you ran RG8 on an 18ft Capri, it would likely turn turtle!

Always minimise weight aloft on a sailing vessel!

GM

Gm1234 wrote:
"tlindly" wrote
RG8 [not 6] is MUCH bigger in diameter than RG58. RG58 is also much
mor flexable.
But I wouldn't recommend it for this length, unless a very sharp bend
is absolutely necessary.
tom



Besides that, if you ran RG8 on an 18ft Capri, it would likely turn turtle!

Always minimise weight aloft on a sailing vessel!

GM


There is a good calculator for coax losses at
http://www.ocarc.ca/coax.htm
A 25W VHF at 156 mhz with 40 ft of RG-58 will have 15.819W at the
antenna. With RG-8X it will be 16.741W. With RG-8U it will be 19.859W.
Assuming a VSWR of 1.3
krj

Matt Colie wrote in :

Well,
It's about time. I was starting to wonder why you had the VHF
tied into the broadband.
Matt



RG-6 would work fine. We've run some bigtime 2 meter repeaters using 75
ohm hardline we got for free from the local cable companies. I used to
have a storage yard under a paging tower that was overrun with it. I gave
it away to anyone who asked for it. Lots of ham radio stations have it
buried in their yards, still, 10-20 years later.

RG-6 is that cable running to your TV in the living room. The direct
burial stuff the cable guys on the trucks have is great. You can lay it
anywhere in the bilge and it won't leak like 8X does....even with the fancy
white cover.

There are even PL-259 UHF crimp-on connectors with sealer built into the
crimp for it.

"Coax is a terrible thing to waste"....(c

krj wrote in news:S6heh.23081$T6.392
@bignews5.bellsouth.net:

A 25W VHF at 156 mhz with 40 ft of RG-58 will have 15.819W at the
antenna. With RG-8X it will be 16.741W. With RG-8U it will be 19.859W.
Assuming a VSWR of 1.3
krj



OK, so here's a little reality check......

Stop by any Radio Shack and look closely at the S-meter on any CB radio
in the shop.

http://www.smeter.net/slc/signal/strengths.php

It doesn't matter this is VHF or HF or whatever. 6db is one S-unit.....

So, 1 s-unit drop is 1/4 the power (1/2 the voltage) of the field,
approximately. This might be important on HF where noise is a factor,
but not VHF because it's LINE OF SIGHT.

From a 50' 3db sailboat antenna, 25 watts = 50W ERP at 50'. 15 watts =
30W ERP at 50'. In BOTH cases, the signal at the RADIO HORIZON is
significantly more than is necessary for solid comms unless you're behind
a 60' wall of seawater (in a trough in 30' seas) which puts the other
station over your radio horizon every 10 seconds and radio is somewhere
down the list of priorities at that moment.

The only place on VHF where 1 S-unit might be a factor is around a busy
marina city where the marina has a 50' tower he shouldn't and a 25W radio
I think should be a violation of his license. It just creates havoc at
distance. Marinas need walkie talkie licenses ONLY. If you want to
reserve a slip, call them on the cellphone, not Ch16. A few of the old
public correspondence channels ought to be converted to marina channels
and they should be restricted to it so boaters can listen to 16 WITHOUT
all those dock calls, which makes you want to turn the volume down from
the constant calling....The 1 S-unit might make a small difference trying
to get an emergency declared when some big Hatteras is calling about a
slip....at 25 watts, of course.

Every marina radio in Charleston is setting on 25 watts. Check yours,
unannounced, and take a sample in your area. Ask the teenaged girl
behind the desk if she sees an H or L on the little screen. She'll have
no idea what it means or how to change it. She's not allowed to do
anything like that....

RG-8X or RG-58A/U or RG-8 (3/4") or RG-17A/U (1.5") won't make a hoot's
difference on the air......to another boat on the horizon.....It's
physics.

krj wrote:

Gm1234 wrote:

"tlindly" wrote

RG8 [not 6] is MUCH bigger in diameter than RG58. RG58 is also much
mor flexable.
But I wouldn't recommend it for this length, unless a very sharp bend
is absolutely necessary.
tom



Besides that, if you ran RG8 on an 18ft Capri, it would likely turn
turtle!

Always minimise weight aloft on a sailing vessel!

GM


Might make a good mizzen mast?
Unstayed???

There is a good calculator for coax losses at

http://www.ocarc.ca/coax.htm

A 25W VHF at 156 mhz with 40 ft of RG-58 will have 15.819W at the
antenna. With RG-8X it will be 16.741W. With RG-8U it will be 19.859W.
Assuming a VSWR of 1.3
krj


Well, considering all aspects of this, RG8 foam core - WELL SEALED
might be the best choice for me.

Now, how to seal up the connectors?

Adhesive lined heat shrink may be fine for the top one, but the
deck connector? That one has to come apart occasionally.

And, it's probably the one most exposed to the spray...

Look up Tommy Tape. It is a self amalgamating plastic tape. You stretch it
as it is applied which frees up the adhesive. Makes a very watertight seal.
Just cut it off when you need to disconnect the cable.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"cavelamb himself" wrote in message
ink.net...
krj wrote:

Gm1234 wrote:

"tlindly" wrote

RG8 [not 6] is MUCH bigger in diameter than RG58. RG58 is also much
mor flexable.
But I wouldn't recommend it for this length, unless a very sharp bend
is absolutely necessary.
tom



Besides that, if you ran RG8 on an 18ft Capri, it would likely turn
turtle!

Always minimise weight aloft on a sailing vessel!

GM


Might make a good mizzen mast?
Unstayed???

There is a good calculator for coax losses at

http://www.ocarc.ca/coax.htm

A 25W VHF at 156 mhz with 40 ft of RG-58 will have 15.819W at the
antenna. With RG-8X it will be 16.741W. With RG-8U it will be 19.859W.
Assuming a VSWR of 1.3
krj


Well, considering all aspects of this, RG8 foam core - WELL SEALED
might be the best choice for me.

Now, how to seal up the connectors?

Adhesive lined heat shrink may be fine for the top one, but the
deck connector? That one has to come apart occasionally.

And, it's probably the one most exposed to the spray...