[pskmail] Re: Amateur radio for northwest passage voyage
- From: "Brett E. Wynkoop" <pskmail@xxxxxxxxx>
- To: pskmail@xxxxxxxxxxxxx
- Date: Tue, 20 Jul 2010 12:24:31 -0400 (EDT)
On 20/Jul/2010 09:14 Gavin Rogers <kc9kvq@xxxxxxxxx> wrote ..
> Hi there,
>
> I have been last-minute added to the crew to sail the Northeast passage
> starting this weekend. I am getting a local antennae pro to install a
> vertical dipole on the main mast, and I'm buying a good used IC706. I have a
> good quality laptop running linux, and I hope to (in addition to normal HAM
> operations and contacts throughout the voyage) send/receive APRS, minimal
> email, and ice charts/weather reports vial PSKmail.
Gavin-
I have been a ham for over 30 years, and have gone to sea on vessels as small as
27 feet to as large as 650 feet over the last 30 years. I am a little worried
about the "vertical dipole" on the mainmast. Remember a dipole will only be
resonate on ond band (2 if we are talking third harmonic on HF). If the mast is
anything that is conductive having an antenna running up the mast is an issue.
If the mast is wood it is less of an issue, but can still be a problem. Beyond
the conductivity of the mast one must also think about things like hardware and
halyards that might cause damage, or be damaged. I am sort of wondering about
your so-called antenna pro.
To get out a good signal from a seagoing platform you need a good ground. You
do not say what sort of vessel it is. If a metal hull then just grounding to
the hull will be find. If you are in a glass, wood, or carbonfiber ship then
you need to look at getting some good metal surface area in contact with the
water. Since you will be trying the northwest passage you must think about ice
damage to any grounding plate you install. Beyond that you need to get as much
antenna in the air as you can. I do not know how your vessel is rigged, but for
a sloop I would go with an insulated backstay, or one of the new around the
backstay antennas. If I were on a Ketch of Schooner I would go with an
insulated backstay (if rigging permits) or insulated side stay connected to an
insulated stay between the masts, again if rigging permits. You want to get the
most wire in the air you can without interfering with the running or standing
rigging. You want a good antenna tunner and you need to know how to use it.
For this application I like manual tuners as they take no extra power from the
vessel systems, but something like the Icom AH-2 or AH-4 will work fine as
well.
I use an AH-4 and insulated backstay on my 27 foot sloop and work the world with
20 watts. Since most of my sailing is in coastal waters I am less worried about
an out of power situation. If I do not have power for radio no big deal I just
plan a course to a harbor where I can fix my power issues in comfort. If you go
with an automatic tunner take along a manual one as backup in case of power
issues, or tuner failure. You will not be fixing an autotuner at sea, but if
you arc over or melt a connection on a manual tuner that can be fixed quickly in
the field. While going to sea professionaly my antenna was usually 50-150 feet
of wire in the superstructure of the freighter and the rig was 2.5 watts ssb and
cw that I could take into a lifeboat with it's battery. I could get contact to
someone with this setup no matter where I was in the world.
If you give some details of your vessel I can give better advice on antenna,
ground, rig, and power. In addition to being an Extra having first been
licensed in 1973 I also hold a commercial license with ship radar endorsement,
so I have some small experience with onboard HF radio systems.
73 & pack your long underware!
-Brett
wa3yre
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