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cavelamb himself December 7th 06 04:26 PM

Antenna cable?
 
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

krj December 7th 06 04:31 PM

Antenna cable?
 
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

Use RG-8x or if you have room for the larger diameter use RG-8U
krj

RW Salnick December 7th 06 05:02 PM

Antenna cable?
 
cavelamb himself inscribed in red ink for all to know:
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


Use RG8 or RG8x

bob
s/v Eolian
Seattle

Mika December 7th 06 05:54 PM

Antenna cable?
 
On Thu, 07 Dec 2006 09:02:14 -0800, RW Salnick
wrote:

cavelamb himself inscribed in red ink for all to know:
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


Use RG8 or RG8x



How long cable? Lower loss cable such as RG8 for masthead
installations, but RG58 is quite ok for shorter cables. BTW, make
sure to use good quality connectors and be carefull that connections
are waterproof. Having boating and ham radio experience for 20 plus
years, 99% of problems have something to do with poor corroded
connections ...

Mika


--
----------------------------------------------------
Haluatko lähettää postia? Vaihda osoitteen
eka (vai oliko se toka?) numero vitonen numeroksi
kahdeksan...
----------------------------------------------------

Glenn Ashmore December 7th 06 06:01 PM

Antenna cable?
 
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.

--
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
nk.net...
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




cavelamb himself December 7th 06 08:30 PM

Antenna cable?
 
Mika wrote:
On Thu, 07 Dec 2006 09:02:14 -0800, RW Salnick
wrote:


cavelamb himself inscribed in red ink for all to know:

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


Use RG8 or RG8x




How long cable? Lower loss cable such as RG8 for masthead
installations, but RG58 is quite ok for shorter cables. BTW, make
sure to use good quality connectors and be carefull that connections
are waterproof. Having boating and ham radio experience for 20 plus
years, 99% of problems have something to do with poor corroded
connections ...

Mika



God is in the details, so they say.

Yes, I'm mounting the antenna on the mast head.
the mast is 24 feet long (hey, it's a Capri 18!).

Add another 10 or 12 feet for routing the cable out of the way in
the cabin...

The antenna is a 3db Shakespear that has a built in cable.
The mounting instructions say the cable can be shortened but must
be at least 3 feet long. I haven't decided whether to coil it up
at the mast head or maybe put a bracket a couple of feet lower to
attach the connectors.

Either way there is a connector at the top of the mast, one at
the bottom (it's a trailerable boat) and one at the radio.

I thought about putting a deck clam near the mast and just
running the cable from the top of the mast to the radio, but
for the fact that we drop the mast to travel several times a year.

I hear ya about connector problems.

The only local source for cable and connectors is Radio Shack(!)
(PL-259 is spec)

Where do I look (and what am I looking for) in regard to connectors?

Richard

BTY, pics of my boat at:
http://www.home.earthlink.net/~cavel...rit.htm#spirit




Jack Erbes December 7th 06 10:16 PM

Antenna cable?
 
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

--
Jack Erbes in Ellsworth, Maine, USA (jackerbes at adelphia dot net)
(also receiving email at jacker at midmaine dot com)

cavelamb himself December 7th 06 10:55 PM

Antenna cable?
 
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

Larry December 8th 06 08:55 AM

Antenna cable?
 
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?

Larry December 8th 06 09:02 AM

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

tlindly December 8th 06 01:30 PM

Antenna cable?
 
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



tlindly December 8th 06 01:36 PM

Antenna cable?
 
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?



Glenn Ashmore December 8th 06 01:45 PM

Antenna cable?
 
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




Matt Colie December 8th 06 01:48 PM

Antenna cable?
 
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


Gm1234 December 8th 06 04:40 PM

Antenna cable?
 

"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



krj December 8th 06 05:17 PM

Antenna cable?
 
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


Larry December 8th 06 06:07 PM

Antenna cable?
 
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;)


Larry December 8th 06 06:36 PM

Antenna cable?
 
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.


cavelamb himself December 8th 06 07:02 PM

Antenna cable?
 
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...

Glenn Ashmore December 8th 06 08:01 PM

Antenna cable?
 
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...




[email protected] December 8th 06 11:53 PM

Antenna cable?
 

Larry is correct. 40' of rg58 with a matched antenna will have about
2db of loss on the marine band. This is nothing to be concerned about.
Nobody can tell, with there ears, the difference between the rg58 vice
LMR400. Use the rg58 and use BNC connectors. You can cut the antenna
cable as short as you want because you are adding another 40' length of
cable. Most laymen just don't understand the relationship between power
output and field strength.

Eric


cavelamb December 10th 06 06:14 PM

Antenna cable?
 

wrote:
Larry is correct. 40' of rg58 with a matched antenna will have about
2db of loss on the marine band. This is nothing to be concerned about.
Nobody can tell, with there ears, the difference between the rg58 vice
LMR400. Use the rg58 and use BNC connectors. You can cut the antenna
cable as short as you want because you are adding another 40' length of
cable. Most laymen just don't understand the relationship between power
output and field strength.

Eric


Thank you Eric.

Well, as a layman I'd have to agree with you there.
That's why I asked all these silly questions.
(a little knowledge is a dangerous thing)

And thanks for the reply about the antenna cable length.
That 3' tail is a problem to deal with neatly.
The instructions that came with the antenna mentioned something like
an 8" minumum bend radius - but at the top of the mast ???

If I can trim it short things work out a lot mo better.

I went into Rat Shack and found a 50' RG58 package with PL259
connectors on
both ends for about $23.

Still have to get it through the deck, but hey - making progress here,
boss.

I photographed my neighbors deck connections (Catalina 27) and put it
at

http://www.home.earthlink.net/~cavel...es/deckpin.jpg

Anybody have a source for these things?

As a side issue, earthlink seems to have lost the news server (again)
so I
crawled in via google groups.

My email address is

Thanks for all the help guys,

Richard


Mika December 10th 06 07:39 PM

Antenna cable?
 
On Fri, 08 Dec 2006 19:02:42 GMT, cavelamb himself
wrote:

krj wrote:

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


Like many people have said, 15 or 20 watts and you cannot hear the
difference. It is antenna height that matters as far as range is
concerned. Masthead installation means antenna us way up, but hard to
fix if something goes wrong. And most likely extra connectors, as you
would need to detach the antenna when you take your mast down.

My VHF antenna is only some 3 meters above deck. Permanent
installation and therefore less maintenance problems. Coast guard
stations 20-30 nautical miles away come in strong since they have
antennas way up in tower, and I can hear and work anything within
visible horizon. If you dont go far offshore, this is enough for
emergency communcations etc.

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


Foam is great for fixed installations such as your ham radio antenna
at home. But I wouldnt use foam for boating installations. Any bends
etc, and center could eventually short circut with shield.

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.


I used just electrican´s tape with masthead antenna installation on my
previous boat. Takes is few minutes to seal up in spring and take off
in fall. If connectors corrode, you can clean the surface or even
replace them every few years. Leave somewhere a few extra inches of
cable so you can replace connectors.

But make sure you seal cable and connector so that water will not
enter cable. Its not a disaster if contact surface corrodes a bit,
but any leak and coax will be filled with water. Still OK to your DC
meter, but water in cable spells very high losses in HF and VHF,
nothing like in line loss calculations when different cable types vere
compared. Cable filled with water is better thrown away.

Mika






--
----------------------------------------------------
Haluatko lähettää postia? Vaihda osoitteen
eka (vai oliko se toka?) numero vitonen numeroksi
kahdeksan...
----------------------------------------------------

[email protected] December 10th 06 10:34 PM

Antenna cable?
 
Iv'e used NewMar's Thru-dex fittings for years. They are a bit pricey
so also take a look at Blue Sea cable clams for about half the price.

http://www.rapidresponsemarine.net/b...-Fittings.html

http://www.consumersmarine.com/modpe...&i=920048&aID=

Both of these allow you to drill a hole large enough for your
connector but still give a good seal.

Eric

cavelamb wrote:

Still have to get it through the deck, but hey - making progress here,
boss.

I photographed my neighbors deck connections (Catalina 27) and put it
at

http://www.home.earthlink.net/~cavel...es/deckpin.jpg

Anybody have a source for these things?



chuck December 11th 06 02:36 PM

Antenna cable?
 
Larry wrote:
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.


These days, an s-unit may turn out to be as small as 3 or 4 dB. Can't go
by the S-meters.

The important comparison for coax is the difference in cable losses in
dB. If the difference between two alternatives is on the order of 1 or 2
dB, it is not likely to be noticeable.

I don't think I saw any comments on foam insulation problems. With sharp
bends, the foam compresses and changes the impedance of the cable
resulting in higher vswr and losses. For sharp bends (less than 6 inch
radius) avoid the foam.

Chuck

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