VHF installation questions
 

Roger's post said he's "looking for more range" than a handheld can
provide; the only way to feel good about an 'installed' VHF (assume
mast mounted antenna) system is to know that the antenna is 'accepting'
all of the power delivered to it (as opposed to 'rejecting', or
'reflecting' some of it back to the transmitter - a rough definition of
'Standing Waves'). If you know any Ham (Amateur Radio) operators, ask
if you can borrow their "Bird Model 43" thruline wattmeter. Easy to
use, and the results will provide peace of mind about your new radios
ability to provide "more range." Note: Because receivers are so
sensitive these days, even a very poorly matched antenna will likely
result in a "sounds ok to me skipper" radio check. This seems to me to
be a poor way to check a vital piece of safety equipment...

MW
Los Angeles

VHF installation questions
 

I just called a marine electronics shop and they said to "just do a
radio check". Couldn't tell me if there was a preferred channel in
this area such as is reported for the West Coast (22 A).

Maybe if I'd bought the radio from them:)

--

Roger Long



wrote in message
oups.com...
Roger's post said he's "looking for more range" than a handheld can
provide; the only way to feel good about an 'installed' VHF (assume
mast mounted antenna) system is to know that the antenna is
'accepting'
all of the power delivered to it (as opposed to 'rejecting', or
'reflecting' some of it back to the transmitter - a rough definition
of
'Standing Waves'). If you know any Ham (Amateur Radio) operators,
ask
if you can borrow their "Bird Model 43" thruline wattmeter. Easy
to
use, and the results will provide peace of mind about your new
radios
ability to provide "more range." Note: Because receivers are so
sensitive these days, even a very poorly matched antenna will likely
result in a "sounds ok to me skipper" radio check. This seems to me
to
be a poor way to check a vital piece of safety equipment...

MW
Los Angeles

VHF installation questions
 

On Thu, 27 Jul 2006 13:28:08 GMT, "Roger Long"
wrote:

I just called a marine electronics shop and they said to "just do a
radio check". Couldn't tell me if there was a preferred channel in
this area such as is reported for the West Coast (22 A).

Maybe if I'd bought the radio from them:)

Make a call to a specific vessel or shore station (marina, yacht club,
SEATOW, etc.), on either ch 16 or 9.

Otherwise you can buy your own SWR bridge for about $40.

VHF installation questions
 

Sorry Chuck, but with frequency modulation (used with marine VHF
radios), the 'loudness' of a received signal has *nothing to do* with
the transmitter's power output or quality of the antenna system. Asking
"can you hear me now?" of a fellow mariner in the same harbor seems a
dubious way of checking the integrity of a vital communications system.
The most likely failure mechanism for an 'old' coax is water migration
into the cable - which generally happens at the antenna connection.
This *will* change the impedance of the cable, which *will* show up on
the thruline, or VSWR meter. "Old coax" in and of itself usually
doesn't "become lossy" simply becuase of it's age; 100 year old copper
conducts just as freely as 'new' copper.

MW

chuck wrote:
I don't think Roger is too interested in measurements, though, and
there is a lot of wisdom in the notion that if you want to know if
your big VHF is louder than your handheld VHF, the best way to find out
is to see if it IS louder. ;-)

VHF installation questions
 

"Wayne.B" wrote in message
...
On Thu, 27 Jul 2006 00:14:14 -0700, "Capt. JG"
wrote:

Here? I sail in the SF area. They don't like being hailed for radio
checks,
and you can't hail on 22a.

A popular radio check strategy around here is to call SeaTow on
channel 16, switch to a working channel, and ask for a signal report.

They seem to be OK with it, and it is a legit use of 16.

I agree... calling SeaTow is a reasonable thing to do. If nothing else, free
advertising for them. :-)

--
"j" ganz @@
www.sailnow.com

VHF installation questions
 

wrote:
Sorry Chuck, but with frequency modulation (used with marine VHF
radios), the 'loudness' of a received signal has *nothing to do* with
the transmitter's power output or quality of the antenna system. Asking
"can you hear me now?" of a fellow mariner in the same harbor seems a
dubious way of checking the integrity of a vital communications system.

Disagree, Mike. My recommendation was
that the squelch be turned down so that
hiss could be heard. FM carriers of
different strengths will differ in the
amount of quieting they produce. It's
pretty intuitive. Even with the squelch
on, weaker signals may not break the
squelch. You're probably thinking of the
limiter function in an FM receiver which
irons out changes in amplitude from the
modulation. But that's not involved in
the weak signal test I suggested.

But I sure agree that "can you hear me
now?" won't do it.

Remember the objective as you yourself
correctly stated it: looking for more
range than the handheld (or,is the Quest
louder than the handheld). With the
squelch down and a distant station
cooperating, I see no reason a simple
and positive comparison of the two
radios can't be made.

Regarding coax, usually there is no
deterioration of the copper itself,
although braids are sometimes eaten away
in a marine environment. What happens is
that the dielectric changes as it
becomes contaminated. Measure the
capacitance of a piece of coax that's
been in a boat for ten years. Additional
shunt capacitance will attenuate
signals. Measure the leakage resistance
between the center conductor and the
braid and compare that to a new cable.

Many sailboats have coax connectors in
or near the bilge at the base of the
mast to facilitate dismasting, and these
connectors tend to be contaminated after
many years.

Chuck

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VHF installation questions
 

In article BxWxg.248882$IK3.66723@pd7tw1no,
Gary wrote:

Like I said, here the Coast Guard tell you to call on 22a. It may be
different where you are. The advantage of a Coast Guard radio check is
the can check your signal on a variety of repeaters and tell you how far
you are going. They can even DF you! Receiving poor signals may be
neccessary if your radio isn't working properly, and they'll tell you
that too.

Bzzzt, Wrong Information..... Maybe the Canadian Coast Guard can do what
you say, but the USCG is about 10 years behind in DCS and Vhf DF
Deployment, and do NOT have that capability on most of the US Coastline.
Yes, they do have a good VHF HighSite Deployment but these are not DCS
or DF Capable, for the most part, and will not be for a few more years.
The congress wants the USCG to be watching for Terrorists not answering
Distress Calls from Idiot Yatchmen.

VHF installation questions
 

wrote:
Sorry Chuck, but with frequency modulation (used with marine VHF
radios), the 'loudness' of a received signal has *nothing to do* with
the transmitter's power output or quality of the antenna system. Asking
"can you hear me now?" of a fellow mariner in the same harbor seems a
dubious way of checking the integrity of a vital communications system.
The most likely failure mechanism for an 'old' coax is water migration
into the cable - which generally happens at the antenna connection.
This *will* change the impedance of the cable, which *will* show up on
the thruline, or VSWR meter. "Old coax" in and of itself usually
doesn't "become lossy" simply becuase of it's age; 100 year old copper
conducts just as freely as 'new' copper.

MW

chuck wrote:
I don't think Roger is too interested in measurements, though, and
there is a lot of wisdom in the notion that if you want to know if
your big VHF is louder than your handheld VHF, the best way to find out
is to see if it IS louder. ;-)

I agree with MW, even pick a few marinas at nearby ports and see how
far away you can hail them from! It just sounds like from a time
standpoint, you could get a simple answer this way the fastest.
Assuming all works acceptable, after the cruise, break out the meters
and get technical. A lot of these users have great ideas for you.