Hi,

I have a Uniden 996 scanner and would really like to pick up some marine
traffic from Boston Harbor.
Live about 20 miles due west of the harbor.

Have a Scantenna antenna which I think is "pretty good". It's up in my
attic.

It's omni directional, and broadband over the typical scanner ranges
(supposedly).

I can often pick up coast guard conversations, but very rarely (but
ooccassionally) ship traffic.

Do you think a dedicated, very directional, and tuned to the marine freq's
would help, or am I just too far away ?

Any thoughts on, or antenna suggestions would be most appreciated.
No idea what to buy, if you feel it's worth a try ?

Very interested in the AIS data being transmitted by ships at around 162
MHz, as well as general marine stuff.

BTW: really surprised that I hear the CG at all. I would have thought that
their antennas would be "focused" out to sea, with any propagation going the
other way (towards me) minimized to maximize the effectiveness of their
radiated power in the direction that it's needed.

Thoughts ?

Thanks,
Bob

On Tue, 12 Jun 2007 09:10:26 -0400, "Robert11"
wrote:

Hi,

I have a Uniden 996 scanner and would really like to pick up some marine
traffic from Boston Harbor.
Live about 20 miles due west of the harbor.

Have a Scantenna antenna which I think is "pretty good". It's up in my
attic.

It's omni directional, and broadband over the typical scanner ranges
(supposedly).

I can often pick up coast guard conversations, but very rarely (but
ooccassionally) ship traffic.

Do you think a dedicated, very directional, and tuned to the marine freq's
would help, or am I just too far away ?

Any thoughts on, or antenna suggestions would be most appreciated.
No idea what to buy, if you feel it's worth a try ?

Very interested in the AIS data being transmitted by ships at around 162
MHz, as well as general marine stuff.

BTW: really surprised that I hear the CG at all. I would have thought that
their antennas would be "focused" out to sea, with any propagation going the
other way (towards me) minimized to maximize the effectiveness of their
radiated power in the direction that it's needed.

Thoughts ?

Thanks,
Bob


I suggest you get your antenna out of the attic and put it outside as
high up as you can get it. For VHF height is everything.

Danny, K6MHE

Robert11 wrote:
Hi,

I have a Uniden 996 scanner and would really like to pick up some marine
traffic from Boston Harbor.
Live about 20 miles due west of the harbor.

Have a Scantenna antenna which I think is "pretty good". It's up in my
attic.

It's omni directional, and broadband over the typical scanner ranges
(supposedly).

I can often pick up coast guard conversations, but very rarely (but
ooccassionally) ship traffic.

Increasing your antenna height would
probably improve reception more than
increasing antenna gain at that distance.

Theoretically, ships will switch to low
power (~5 watts) when they enter the
harbor, but you should still hear them.

I think pilot-to-tug communication is
done with portable, hand-held radios.
Very low power is needed for distances
on the order of a few hundred feet and
antenna height is quite close to the
water. So you may not be able to hear
these communications from your distance.

If you look he

http://209.85.165.104/search?q=cache...lnk&cd=2&gl=us
Chapter 11 â–* Coast Pilot 1

you will find some info on which VHF
channels ships would normally use (#13)
in their approach to Boston Harbor.
Also, you can see that transmissions are
brief and occur at specific points.

Unlike the USCG, which recites a 1,000
word, mostly unintelligible, preamble to
every announcement, ship traffic in a
crowded harbor is likely to be terse and
easy to miss.

A call to the Harbormaster or a posting
to a marine newsgroup
(rec.boat.electronics) could get a more
definitive answer.

Chuck

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
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On Jun 12, 7:10 am, "Robert11" wrote:
Hi,


Do you think a dedicated, very directional, and tuned to the marine freq's
would help, or am I just too far away ?

Sure, I did the same thing once. Except I'm 55-65 miles from the
gulf, instead of 20.. I built a 4 el yagi for 162 mhz.
Worked great, and I could hear boats that didn't exist on the
omni vertical.
MK

wrote in message
ups.com...
On Jun 12, 7:10 am, "Robert11" wrote:
Hi,


Do you think a dedicated, very directional, and tuned to the marine
freq's
would help, or am I just too far away ?

Sure, I did the same thing once. Except I'm 55-65 miles from the
gulf, instead of 20.. I built a 4 el yagi for 162 mhz.
Worked great, and I could hear boats that didn't exist on the
omni vertical.
MK


I used to pick up tons of stuff about 20 miles away with just a vertical
antenna at about 50 ft.
My experience with VHF/UHF in the attic has not been good. I think asphalt
shingles are pretty good RF absorbers at that frequency.

Jimmie

"Robert11" wrote in message
. ..
Hi,

I have a Uniden 996 scanner and would really like to pick up some marine
traffic from Boston Harbor.
Live about 20 miles due west of the harbor.

Have a Scantenna antenna which I think is "pretty good". It's up in my
attic.

It's omni directional, and broadband over the typical scanner ranges
(supposedly).

I can often pick up coast guard conversations, but very rarely (but
ooccassionally) ship traffic.

Do you think a dedicated, very directional, and tuned to the marine freq's
would help, or am I just too far away ?

Any thoughts on, or antenna suggestions would be most appreciated.
No idea what to buy, if you feel it's worth a try ?

Very interested in the AIS data being transmitted by ships at around 162
MHz, as well as general marine stuff.

BTW: really surprised that I hear the CG at all. I would have thought
that their antennas would be "focused" out to sea, with any propagation
going the other way (towards me) minimized to maximize the effectiveness
of their radiated power in the direction that it's needed.

Thoughts ?

Thanks,
Bob

Hi Bob

Do you want to try building your own antenna? If so, I'd think a simple
antenna like a J-pole ( http://www.hamuniverse.com/jpole.html ) would be
worth trying.

Jerry

"Jerry Martes" wrote in message
news:TYAbi.3722$O15.28@trnddc03...

"Robert11" wrote in message
. ..
Hi,

I have a Uniden 996 scanner and would really like to pick up some marine
traffic from Boston Harbor.
Live about 20 miles due west of the harbor.

Have a Scantenna antenna which I think is "pretty good". It's up in my
attic.

It's omni directional, and broadband over the typical scanner ranges
(supposedly).

I can often pick up coast guard conversations, but very rarely (but
ooccassionally) ship traffic.

Do you think a dedicated, very directional, and tuned to the marine
freq's would help, or am I just too far away ?

Any thoughts on, or antenna suggestions would be most appreciated.
No idea what to buy, if you feel it's worth a try ?

Very interested in the AIS data being transmitted by ships at around 162
MHz, as well as general marine stuff.

BTW: really surprised that I hear the CG at all. I would have thought
that their antennas would be "focused" out to sea, with any propagation
going the other way (towards me) minimized to maximize the effectiveness
of their radiated power in the direction that it's needed.

Thoughts ?

Thanks,
Bob

Hi Bob

Do you want to try building your own antenna? If so, I'd think a simple
antenna like a J-pole ( http://www.hamuniverse.com/jpole.html ) would be
worth trying.

Jerry






Yes it is worth trying. I can pick a telemetry transmitter nearly 30 miles
away that only puts out about 5 watts on just above 400Mhz. There are 2
transmitters there and I can only pick up one .The one I cant pick up has
its antenna at about 20ft above the ground , the other is a 50 ft. Just an
example of what a difference heigth makes.

Jimmie

In article ,
Robert11 wrote:

Have a Scantenna antenna which I think is "pretty good". It's up in my
attic.

It's omni directional, and broadband over the typical scanner ranges
(supposedly).

I can often pick up coast guard conversations, but very rarely (but
ooccassionally) ship traffic.

Do you think a dedicated, very directional, and tuned to the marine freq's
would help, or am I just too far away ?

Could very well help, especially if you can get it up above the attic
into clear air. In fact, the height of the antenna may make more
difference than antenna gain/directionality.

My guess is that your current antenna is high enough up to pick up the
shore antennas (which are probably tower- or building-mounted) but is
too low to be in good line-of-sight to the ships themselves.

Review the page at http://www.connect802.com/height.htm - it has a
chart showing the required height-above-ground of an antenna, to "see"
another antenna past the earth's curvature.

Any thoughts on, or antenna suggestions would be most appreciated.
No idea what to buy, if you feel it's worth a try ?

Take a look at

http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf

Simple, decent-performing Yagi antennas that you can throw together
with a piece of one-by-two wood for the beam, some stiff copper wire,
and a soldering iron.

I'd suggest taking the dimensions for the simplest (3-element) 144 MHz
antenna, and rescaling them all by a factor based on the _highest_
marine-band frequency you want to receive. You'll need to rescale the
element lengths, and the distances between the elements. You'll end
up with a Yagi which is intermediate in size between the 144- and
220-MHz versions.

Very interested in the AIS data being transmitted by ships at around 162
MHz, as well as general marine stuff.

BTW: really surprised that I hear the CG at all. I would have thought that
their antennas would be "focused" out to sea, with any propagation going the
other way (towards me) minimized to maximize the effectiveness of their
radiated power in the direction that it's needed.

At most, I'd think that they'd use an antenna with a cardioid or
off-center-circular pattern, so that a single shore station's signal
would cover the whole half-circle with fairly equal power. There's
probably still quite a bit of back-spill towards shore - plenty enough
for you to receive. They wouldn't use (or need to use) an antenna
with an extremely high front-to-back ratio, because they have no need
to "reject" transmissions from shore-side... since there probably
aren't any. Increasing the front-to-back ratio would just add
complexity and expense to the antenna, reducing its overall
reliability (more things to break), at no significant benefit in
received-signal quality or desired-direction output power.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Jun 12, 11:10 pm, "Robert11" wrote:
Hi,

I have a Uniden 996 scanner and would really like to pick up some marine
traffic from Boston Harbor.
Live about 20 miles due west of the harbor.

Have a Scantenna antenna which I think is "pretty good". It's up in my
attic.

It's omni directional, and broadband over the typical scanner ranges
(supposedly).

I can often pick up coast guard conversations, but very rarely (but
ooccassionally) ship traffic.

Do you think a dedicated, very directional, and tuned to the marine freq's
would help, or am I just too far away ?

Any thoughts on, or antenna suggestions would be most appreciated.
No idea what to buy, if you feel it's worth a try ?

Very interested in the AIS data being transmitted by ships at around 162
MHz, as well as general marine stuff.

BTW: really surprised that I hear the CG at all. I would have thought that
their antennas would be "focused" out to sea, with any propagation going the
other way (towards me) minimized to maximize the effectiveness of their
radiated power in the direction that it's needed.

Thoughts ?

Thanks,
Bob

hi bob ..if you want really good reception on vhf marine band ,you
should consider buying a ham 2mtr band base antenna .
these work on 147mhz and will work just as good on the marine band for
receive.

hope this helps ...
bob vk4la in australia

"Robert11" wrote in message
. ..
Hi,

I have a Uniden 996 scanner and would really like to pick up some marine
traffic from Boston Harbor.
Live about 20 miles due west of the harbor.


snip

No idea what to buy, if you feel it's worth a try ?

snip

Thoughts ?

I googled for marine band colinear and got this near the top:
http://buyreliant.com/marine/5102.htm It's way cheaper than some name-brand
competitors, like Shalespeare, but you're not going to be stressing it on a
boat, so give it a try on your rooftop or chimney.