On Sun, 18 Jan 2004 06:15:40 -0500, "Bruce"
wrote:

Brian and Gary...good stuff. Now understanding the loss of power, it
would make sense to get an amp (Idon't think it would be legal) or have a
second line run to the spreader on the mizzen.That would drop the run down
to 30' and a corresponding increase in power.
Thanks for you help
Bruce

The amp IS illegal under normal use. However, most don't realize that
in an emergency situation where life is endangered, all radio laws are
null and void and any power is fine if it saves lives.



Larry W4CSC

As has been pointed out, the cable loss (within reason), is a somewhat moot point.

Given an antenna height of X, it is not hard to calculate the maximum expected range, plus some for
refraction, then also given the typical receiver sensitivity, (assume 10 microvolts for a
not-so-good receiver), and antenna gain, you'll find that the power required at the antenna is not
much. When the boat's rock and roll effect on the antenna pattern is considered, the power
requirements of course must go up. As a side note: low gain antennas are better in this respect,
assuming the low gain is due to an wider vertical beam-width, and not just poor design.

But in my estimation, the real key to reliable marine VHFcommunications is in the connectors.

When a young lad I spent 5 years maintaining antennas (all frequencies) in a coastal environment,
(actually, within 200 yards of the beach) and can assure you that an unprotected/exposed connector
in salt air can bring an antenna to its knees in 3 to 6 months.

Norm

As has been pointed out, the cable loss (within reason), is a somewhat moot point.

Given an antenna height of X, it is not hard to calculate the maximum expected range, plus some for
refraction, then also given the typical receiver sensitivity, (assume 10 microvolts for a
not-so-good receiver), and antenna gain, you'll find that the power required at the antenna is not
much. When the boat's rock and roll effect on the antenna pattern is considered, the power
requirements of course must go up. As a side note: low gain antennas are better in this respect,
assuming the low gain is due to an wider vertical beam-width, and not just poor design.

But in my estimation, the real key to reliable marine VHFcommunications is in the connectors.

When a young lad I spent 5 years maintaining antennas (all frequencies) in a coastal environment,
(actually, within 200 yards of the beach) and can assure you that an unprotected/exposed connector
in salt air can bring an antenna to its knees in 3 to 6 months.

Norm

In article ,
"Bruce" wrote:

I am looking at the Ancor brand RG-8x which has tined stranded core. Could
I also use this type wire for the 10' run from my SSB tuner to the backstay?
What I had on the SSB was GTO-15???
Thanks
Bruce
"Brian Whatcott" wrote in message
news
I recommend checking with suppliers' specifications for cable
construction materials: solid or stranded? solid or foam insulation?
%coverage of shield? Tape wrap? Non-acid outer sheath? before
blindly implementing Larry's recommendation below on choosing
cables. Yes: let's call it a reality check.

Brian W



On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote:

... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top
with about 75' of RG-58A/U military surplus cable///
If I had to start from scratch, and couldn't buy a 500' roll of
surplus RG-58A/U for $10 at my local thrift shop...

I recommend using VERY flexible, and reliable,
Polyethelene-cored, finely stranded center conductor RG-58A/U (not
RG-58/U which has a solid center conductor) for your purpose. All
those fancy loss charts mean nothing when the fancy foam cables are
pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U
in a hangman's noose and it'll still work great! REALITY CHECK!!



You could but it wouldn't have the insulation capabilities of the GTO-15
that was there in the first place. the installer used GTO-15 for a
reason, can you figure out why? When you do you will have answered your
own question.

Bruce in alaska
--
add a 2 before @

In article ,
"Bruce" wrote:

I am looking at the Ancor brand RG-8x which has tined stranded core. Could
I also use this type wire for the 10' run from my SSB tuner to the backstay?
What I had on the SSB was GTO-15???
Thanks
Bruce
"Brian Whatcott" wrote in message
news
I recommend checking with suppliers' specifications for cable
construction materials: solid or stranded? solid or foam insulation?
%coverage of shield? Tape wrap? Non-acid outer sheath? before
blindly implementing Larry's recommendation below on choosing
cables. Yes: let's call it a reality check.

Brian W



On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote:

... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top
with about 75' of RG-58A/U military surplus cable///
If I had to start from scratch, and couldn't buy a 500' roll of
surplus RG-58A/U for $10 at my local thrift shop...

I recommend using VERY flexible, and reliable,
Polyethelene-cored, finely stranded center conductor RG-58A/U (not
RG-58/U which has a solid center conductor) for your purpose. All
those fancy loss charts mean nothing when the fancy foam cables are
pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U
in a hangman's noose and it'll still work great! REALITY CHECK!!



You could but it wouldn't have the insulation capabilities of the GTO-15
that was there in the first place. the installer used GTO-15 for a
reason, can you figure out why? When you do you will have answered your
own question.

Bruce in alaska
--
add a 2 before @

To those that say a few db extra cable loss does not make any
difference consider the following:

Every time you double the height of your VHF antenna you gain 6 db in
signal strength.

6 db signal strength increase at 30 miles accounts for about 3 extra
miles in range.

The amount of loss you have in the cable or because of low antenna
height effects the receiver the same as it does the transmitter.

With an extra 6 db of cable loss you will hear 3 miles less at 30
miles.

When you add antenna height you pick up signal gain from added height
but also increase cable loss due to longer antenna cable length.

There will be a point with a given type of cable that when you double
the height to gain another 6 db you will also lose 6 db in cable loss.
As an example with RG58 at 6 db loss per 100 feet, if you were at 100
feet and went to 200 feet antenna height you would pick up 6 db from
height but would also loose 6 db in additional cable loss.
If you continued to use RG58 it would do no good to increase the
antenna height at that point.

At lower, more practical heights, that are associated with boats the
same problem exists but to a lesser extent. Because you have not
reached the gain / loss (height / cable loss) at lower heights you
still have a gain when you increase antenna height.
But if you use better cable you can realize more of the height
advantage than with higher loss cable.

Remember, every little few db of gain or loss helps. They all add up.

You could reduce your power a few watts and loose a couple of db. You
could use higher loss cable and loose a couple of db. You could mount
your antenna a little lower and loose a few more db. Pretty soon you
have some significant loss. Will you notice the difference in signal
strength when signals are good, no. Can you still talk, sure. Can you
talk as far, no.

To my way of thinking why leave a few db of signal strength laying on
the deck when all you have to do is use a little better cable. That is
probably the cheapest way of all in gaining a few db of signal
strength.

Regards
Gary


On Sun, 18 Jan 2004 06:15:40 -0500, "Bruce"
wrote:

Brian and Gary...good stuff. Now understanding the loss of power, it
would make sense to get an amp (Idon't think it would be legal) or have a
second line run to the spreader on the mizzen.That would drop the run down
to 30' and a corresponding increase in power.
Thanks for you help
Bruce
"Gary Schafer" wrote in message
.. .
This is the same Larry that says that he has a 150 watt VHF amplifier
to switch in the antenna line if he can't be heard.
Yet he recommends using lossy rg58 cable. Old surplus stuff at that!
When cable ages it does not always do so gracefully. The dielectric
breaks down and the losses can be considerably higher than new cable.

For the amount of work involved and the minimal cost of 100 feet of
RG8 type cable, use the best NEW cable.
RG8 with polyethylene insulation is the way to go unless you have a
size restraint. And forget the aluminum wrap shield stuff. You are
asking for trouble in the marine environment with aluminum.
You do not need "high shielding" for a VHF radio.
Foam insulation is not a good idea on a boat though. The center does
migrate at bends. It is also very difficult to install connectors on
foam cable. The heat from the soldering iron melts the insulation
quickly and lets the center wire move to the side. Sometimes even
shorting it.

Regards
Gary


On Sat, 17 Jan 2004 18:53:08 GMT, Brian Whatcott
wrote:

I recommend checking with suppliers' specifications for cable
construction materials: solid or stranded? solid or foam insulation?
%coverage of shield? Tape wrap? Non-acid outer sheath? before
blindly implementing Larry's recommendation below on choosing
cables. Yes: let's call it a reality check.

Brian W



On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote:

... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top
with about 75' of RG-58A/U military surplus cable///
If I had to start from scratch, and couldn't buy a 500' roll of
surplus RG-58A/U for $10 at my local thrift shop...

I recommend using VERY flexible, and reliable,
Polyethelene-cored, finely stranded center conductor RG-58A/U (not
RG-58/U which has a solid center conductor) for your purpose. All
those fancy loss charts mean nothing when the fancy foam cables are
pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U
in a hangman's noose and it'll still work great! REALITY CHECK!!

To those that say a few db extra cable loss does not make any
difference consider the following:

Every time you double the height of your VHF antenna you gain 6 db in
signal strength.

6 db signal strength increase at 30 miles accounts for about 3 extra
miles in range.

The amount of loss you have in the cable or because of low antenna
height effects the receiver the same as it does the transmitter.

With an extra 6 db of cable loss you will hear 3 miles less at 30
miles.

When you add antenna height you pick up signal gain from added height
but also increase cable loss due to longer antenna cable length.

There will be a point with a given type of cable that when you double
the height to gain another 6 db you will also lose 6 db in cable loss.
As an example with RG58 at 6 db loss per 100 feet, if you were at 100
feet and went to 200 feet antenna height you would pick up 6 db from
height but would also loose 6 db in additional cable loss.
If you continued to use RG58 it would do no good to increase the
antenna height at that point.

At lower, more practical heights, that are associated with boats the
same problem exists but to a lesser extent. Because you have not
reached the gain / loss (height / cable loss) at lower heights you
still have a gain when you increase antenna height.
But if you use better cable you can realize more of the height
advantage than with higher loss cable.

Remember, every little few db of gain or loss helps. They all add up.

You could reduce your power a few watts and loose a couple of db. You
could use higher loss cable and loose a couple of db. You could mount
your antenna a little lower and loose a few more db. Pretty soon you
have some significant loss. Will you notice the difference in signal
strength when signals are good, no. Can you still talk, sure. Can you
talk as far, no.

To my way of thinking why leave a few db of signal strength laying on
the deck when all you have to do is use a little better cable. That is
probably the cheapest way of all in gaining a few db of signal
strength.

Regards
Gary


On Sun, 18 Jan 2004 06:15:40 -0500, "Bruce"
wrote:

Brian and Gary...good stuff. Now understanding the loss of power, it
would make sense to get an amp (Idon't think it would be legal) or have a
second line run to the spreader on the mizzen.That would drop the run down
to 30' and a corresponding increase in power.
Thanks for you help
Bruce
"Gary Schafer" wrote in message
.. .
This is the same Larry that says that he has a 150 watt VHF amplifier
to switch in the antenna line if he can't be heard.
Yet he recommends using lossy rg58 cable. Old surplus stuff at that!
When cable ages it does not always do so gracefully. The dielectric
breaks down and the losses can be considerably higher than new cable.

For the amount of work involved and the minimal cost of 100 feet of
RG8 type cable, use the best NEW cable.
RG8 with polyethylene insulation is the way to go unless you have a
size restraint. And forget the aluminum wrap shield stuff. You are
asking for trouble in the marine environment with aluminum.
You do not need "high shielding" for a VHF radio.
Foam insulation is not a good idea on a boat though. The center does
migrate at bends. It is also very difficult to install connectors on
foam cable. The heat from the soldering iron melts the insulation
quickly and lets the center wire move to the side. Sometimes even
shorting it.

Regards
Gary


On Sat, 17 Jan 2004 18:53:08 GMT, Brian Whatcott
wrote:

I recommend checking with suppliers' specifications for cable
construction materials: solid or stranded? solid or foam insulation?
%coverage of shield? Tape wrap? Non-acid outer sheath? before
blindly implementing Larry's recommendation below on choosing
cables. Yes: let's call it a reality check.

Brian W



On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote:

... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top
with about 75' of RG-58A/U military surplus cable///
If I had to start from scratch, and couldn't buy a 500' roll of
surplus RG-58A/U for $10 at my local thrift shop...

I recommend using VERY flexible, and reliable,
Polyethelene-cored, finely stranded center conductor RG-58A/U (not
RG-58/U which has a solid center conductor) for your purpose. All
those fancy loss charts mean nothing when the fancy foam cables are
pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U
in a hangman's noose and it'll still work great! REALITY CHECK!!

On Sun, 18 Jan 2004 23:46:55 GMT, Gary Schafer wrote:

To those that say a few db extra cable loss does not make any
difference consider the following:

Every time you double the height of your VHF antenna you gain 6 db in
signal strength.

Never heard this...any sources I can refer to? None of my books suggest this.

If true...
5 to 10 feet = +6 dB
10 to 20 feet = 12dB
20 to 40 feet = 18dB
40 to 80 feet = 24dB
80 to 160 feet = 30dB, which is 1000 times the power supplied at the transmitter end of the cable.

6 db signal strength increase at 30 miles accounts for about 3 extra
miles in range.

Can you please show the calculations? Or a pointer?
Thanks,
Norm

On Sun, 18 Jan 2004 23:46:55 GMT, Gary Schafer wrote:

To those that say a few db extra cable loss does not make any
difference consider the following:

Every time you double the height of your VHF antenna you gain 6 db in
signal strength.

Never heard this...any sources I can refer to? None of my books suggest this.

If true...
5 to 10 feet = +6 dB
10 to 20 feet = 12dB
20 to 40 feet = 18dB
40 to 80 feet = 24dB
80 to 160 feet = 30dB, which is 1000 times the power supplied at the transmitter end of the cable.

6 db signal strength increase at 30 miles accounts for about 3 extra
miles in range.

Can you please show the calculations? Or a pointer?
Thanks,
Norm

On Sat, 17 Jan 2004 06:01:33 GMT, (Larry W4CSC) wrote:

All these numbers mean NOTHING if you pull foam cable around a CORNER.
The solid center conductor migrates through the flimsy foam that gives
it such a great set of numbers and it goes all to hell......

Solid center conductors also BREAK if you bend them back and forth as
the loose cable in the mast moves back and forth and back and forth on
every wave.

RG-58A/U has the same loss AFTER you pull it than when it was on the
reel. It's very flexible, finely stranded center conductor and very
hard polyethelene dielectric will take a helluva beating with no
migration around tight turns.

Most boats I know have no room for inch and a half hardline from the
radio to the mast......dammit. 58A/U (not 58/U which is solid
centered) works great for years and years......It's made for MOBILE
service.

Gee, thanks, Larry...here I thought I was screwing up...

My radio experience is painfully limited...as a teen in the '70s I ran
a 40 channel CB base station and used RG-8U...soldered my own
connections and all and put up a free-standing 30 foot tower and
directional antenna (squeaky pulley!). I know 58U was for cars, and
there was no way I was running expensive and heavy 8U up my mast, so I
used 58A/U for the 50 foot run from mast head to a splitter (for AM/FM
radio) under a settee and a further 10 feet to my VHF unit at the nav
station.

I tried a "real world" test with local Coast Guard (5x5 to receivers
about 1,200 higher than me 20 miles away) and with my wife talking to
me in a Zodiac from the boat at dawn some 7 miles away (reckoning by
GPS) over some intervening low land. I could hear her on my handheld
quite well, and she could hear me weakly, but clearly.

So I have no qualms about the 58A/U, the ICOM base unit and the old
whip antenna on a Metz mount...standard coaster rig and good for my
end of Lake Ontario, it seems.

Most of the time I use the handheld (a Standard Horizon 260S with
which I am quite pleased) in the cockpit anyway and save the base unit
for American WX and ship/bridge traffic and whatnot.

My .02 (1.4 U.S)

R.