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Old 01-08-2007, 12:19   #1
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Using SSB longwire for Navtex fax receiver?

I'm installing a Fururno Fax-30 receiver and am wanting to use my Marine HF longwire antenna as it's antenna, too, without of course frying the Fax-30 if/when transmitting on the HF.

I'm looking at antenna switches, but am trying not to have to extend the HF antenna cable off back of the tuner, in rear of boat, and then into the cabin for the switch and then back out again to the antenna, etc.

On the cheap, could I instead simply utilize a hefty alligator type clip on the end of the Fax-30 antenna cable where I'd leave it clipped onto the longwire to recieve navtex and faxes and then remove it if needing to transmit on the HF?

Or, is there another better removeable connection I should explore using?

Any other suggestions or cautions to consider here?

Thank you,
Shane
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Old 01-08-2007, 12:39   #2
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Alpha Delta ďDelta2BĒ ?
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Old 01-08-2007, 14:21   #3
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Unplug the connector from your SSB and plug it into the common port of the coaxial switch. Then make up two coax cables for the SSB and FAX.

Eric
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Old 01-08-2007, 15:03   #4
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Thanks, GordMay, was looking at MFJ Products, but now got a Alpha Delta 2B ordered.

Quote:
Originally Posted by fairbank56
Unplug the connector from your SSB and plug it into the common port of the coaxial switch. Then make up two coax cables for the SSB and FAX.
Eric
Eric, there's an Icom antenna tuner between the HF set and the longwire antenna. Is it OK to have the switch and Fax-30 connected before that tuner?

- Shane
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Old 02-08-2007, 05:17   #5
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Iíve installed (but never used, myself) owner supplied MFJ-1702C Antenna Switches, which (I believe) are cheaper than the Deltas.

Perhaps Bill < btrayfors > could weigh in on the relative merits of these products (and/or other solutions)?
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Old 02-08-2007, 06:06   #6
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Quote:
Originally Posted by shanec
Eric, there's an Icom antenna tuner between the HF set and the longwire antenna. Is it OK to have the switch and Fax-30 connected before that tuner?
Yes, but you will need to turn the SSB on to energize the tuner when using the FAX. With the tuner off, all the coils in the tuning network are in series with the antenna input. Turning the tuner on will energize the network relays and take them all out. You can also tune the tuner to a marine band near the FAX frequency you want to use and this may improve the signal even more. Just remember to turn the coax switch to the SSB position before tuning and then back over to the FAX position.

Eric
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Old 02-08-2007, 09:41   #7
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The NAVTEX receives at a medium frequency and should come with it's own antenna. My Furuno NAVTEX did, a white mushroom type antenna.
It does not have to be mounted high as the signals follows the curvature of the earth.

I would not screw around with the SSB antenna, you forget to flip the switch one time and you are sending 150 watts of power into the NAVTEX, then the party is over....
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Old 02-08-2007, 10:28   #8
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The Furuno Fax30 is a Weatherfax/Navtex receiver. The FAX5 active coupler/antenna is an additional very expensive option for this receiver. It is very common to use the SSB antenna as a shared antenna between a weatherfax and SSB. If the switch is in the wrong position, you will not be transmitting into your Fax but will be transmitting without an antenna connected. The simple solution is to put a permanent tag next to your microphone reminding you to check the switch before transmitting.

Eric
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Old 02-08-2007, 10:47   #9
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Quote:
Originally Posted by CSY Man
The NAVTEX receives at a medium frequency and should come with it's own antenna. My Furuno NAVTEX did, a white mushroom type antenna.
It does not have to be mounted high as the signals follows the curvature of the earth.

I would not screw around with the SSB antenna, you forget to flip the switch one time and you are sending 150 watts of power into the NAVTEX, then the party is over....
CSY Man, I don't think we are both talking about the Furuno Fax-30 receiver which the installation directions call for either a 15 meter or longer wire antenna or a 6 meter whip or a 2.6 meter whip with a pre-amp per section 7 here...
http://www.furuno.com/Furuno/Doc/0/A...01.22.2003.pdf

The mushroom antenna you mentioned sounds like a gps antenna or sat antenna for the Furuno Sirius weather receiver.

Edited to add: Yes, sorry, I did find Furuno has other Navtex units with smaller antennas like you described.

Regardless, yes, I agree, I sure don't want to fry the unit with the SSB.

- Shane
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Old 02-08-2007, 10:51   #10
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Quote:
Originally Posted by fairbank56
The simple solution is to put a permanent tag next to your microphone reminding you to check the switch before transmitting.

Eric
Yes, especially with two teenagers aboard, I might even just disconnect the mic, too, just to be sure the warning note is first heeded!

- Shane
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Old 02-08-2007, 10:55   #11
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Yes, but as I said, you will not be transmitting into your Fax. And I don't know what SSB you have, but most modern ones have high swr protection and will fold back the power if you try transmitting into an open circuit. It's also quite evident that the coax switch is in the wrong position when you hear very little noise from the SSB speaker. But still, a warning tag is a good idea.

Eric
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Old 02-08-2007, 11:13   #12
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Quote:
Originally Posted by fairbank56
Yes, but as I said, you will not be transmitting into your Fax.
That's right, got it now.

This weekend I'll get the specific model number for that ICOM tuner and then see what more I can find out about running the Fax-30 through it, good/bad/ugly.

Thanks, all, for your input here.

- Shane
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