sharing antenna between ssb and weather fax
 

I have an ICOM 802 SSB and have set up my backstay on my sailboat as the antenna. My boat came with a Furuno weatherfax (208A) which I have never used. We can't find an antenna for it on the boat. Can I connect the weather fax to the backstay antenna and share it with the SSB ? If so do I need a switch to toggle to the device that is in use or can they compatibly share the one antenna.

Please forgive me if this is a stupid question....just learning...only have my Technician Ham license so far.

thanks for any help you can offer -

sharing antenna between ssb and weather fax
 

Virginia johns wrote in
:


I have an ICOM 802 SSB and have set up my backstay on my sailboat as
the antenna. My boat came with a Furuno weatherfax (208A) which I
have never used. We can't find an antenna for it on the boat. Can I
connect the weather fax to the backstay antenna and share it with the
SSB ? If so do I need a switch to toggle to the device that is in use
or can they compatibly share the one antenna.

Please forgive me if this is a stupid question....just learning...only
have my Technician Ham license so far.

thanks for any help you can offer -

Virginia,

It is most unlikely that you can connect both a transmitter and a
receiver to the same feedline, it will almost certainly destroy the
receiver.

You can connect two receivers to the same feedline, albeit with some
reduction in performance, but it might not matter much on the lower
parts of HF.

Some, but few, transcievers provide access to the antenna when switched
through to the receiver. If you have that facility, you could use it,
otherwise you could devise some kind of switching arrangement that
reliably prevents the Weatherfax receiver getting a dose of the
transmitter output.

Using a separate antenna for the Weatherfax might seem a solution, but
it needs to provide sufficient isolation so that the energy coupled into
the Weatherfax receiver input is below its damage threshold... and
some.

Owen

sharing antenna between ssb and weather fax
 

Owen Duffy wrote:

Using a separate antenna for the Weatherfax might seem a solution, but
it needs to provide sufficient isolation so that the energy coupled into
the Weatherfax receiver input is below its damage threshold... and
some.

There are lots of other options.

The simplest is a switch. Not a home TV antenna switch, but a ham radio or
commercial grade switch.

The second would be an Ameco PT-3 preamp with a the second receiver
modification. The modification is simple and can be easily done.
The downside of it is that it is not desgined to be in a boat (and therefore
not splash resistant), is extra weight, another device that uses 12 volts
and if you are using both at around the same time, they have to be near
each other in frequency.

The advantage is you get an extra 18db gain out of your receive antenna,
a sharply tuned preselector and it automaticly switches the weather fax
out of the circuit when you transmit.

The third is IMHO the best. If you have a computer on the boat, ditch the
weatherfax entirely. Use the receiver of the ham/commerical radio for
the weatherfax and the computer to decode the images.

Note that you can not legally use a ham radio on marine frequencies, BUT
you can use a marine radio on ham frequencies (with the appropriate licenses).

Ham radios with general coverage receivers are small and relatively cheap,
for example the Yaseu FT-817, the ICOM IC-703 or IC-706 and the older (but still
available used) Kenwood TS-50.

If you have a computer, you can also use it to download weather maps,
etc from the internet. If you are close (35km or less) to land, you can
get a cellular modem and out on the open water you can use a satellite phone.
Cellular modems are expensive to use if you are not in an area covered by your
regular carrier, and satellite phones are very expensive to use.

It's a question of whether you want to get your weather information from
a slow, unreliable, but free source (the weatherfax), or a more expensive,
but quicker and more reliable (download) one.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
To help restaurants, as part of the "stimulus package", everyone must order
dessert. As part of the socialized health plan, you are forbidden to eat it. :-)

Thanks Geoff. We do plan on getting weather fax on the computer too (we have a pactor modem and sailmail subscription) but since we had the older separate fax machine we thought it would be good to have it running as a backup. So thank you for all the options.

Virginia

Thanks Owen for such a quick reply.

Virginia