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Old 13-10-2011, 17:32   #31
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Re: Emergency VHF Antenna Question

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Originally Posted by deckofficer View Post
Wotname has the best and easiest method for the VHF antenna. Foggysail, I switched gears and was talking about HF. The Atlas 210 was the 1st solid state final of HF radios with 100 watt output. It did have a VFO for frequency selection. My first transmitter was a Knight Kit T-60, a tube radio, 60 watt output, CW and AM only, and back then cyrstal controlled. But as a novice HAM in 1963, that was all the regs allowed. There just has to be someone that remembers the Atlas 210 SSB HF from the mid 70's on this forum. It WAS the hot ticket for cruising back in the day, ran on 12 volts.
OK---HF is very different and if I remember correctly stuff in that frequency range required a loading coil. And most were much higher in power than VHF stuff. HEY!!! KNIGHT KIT!!! I never built one but I sure remember them along with an 807 pentode that was great for code transmissions. Yeah-- gone are the good old days. Most guys made their own transmitters, some even made their own receivers and that was an undertaken.

Remember the old BC-221 frequency measurement equipment?

Well, this is getting too far off topic.

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Old 18-10-2011, 05:18   #32
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Re: Emergency VHF Antenna Question from coax

The original question was: can I make an emergency antenna from the (a) remaining coax (RG58 or alike).
Yes, assuming you can recover the coax e.g. pulling it from inside the mast.

How you make it, without any soldering or complex manipulations:

- cut the free end of the coax cleanly
- for 156.800 Mhz, measure a length of 46 cm (18.1") on the outer mantle from the end.
- carefully cut the outer plastic mantle, pulling it off and exposing 18.1" of the braid
- just above the remainder of the plastic outer mantle, carefully pry open the braid with a fine tipped srewdriver or alike, until wide enough to be able to pull out the inner coax lead...if you are a bit handy this should work
- you will end up with your coax and on the end about 18" of outer barid and 18" of coax inner lead...
- there you have your 2 legs of your 156.8 Mhz dipole
- attach some thin rope to a spare halyard or maybe the topping lift.
- tape the top of the inner coax lead at the top, the top of the loose outerbraid about 36" lower, and some more tape where both come out of the rest of the coax, there you have your emergency VHF dipole.
- hoist it into the mast as high as posible, just take care the braid part isn't touching the mast or any stays and at least try pulling away the coax a bit from the lower legg of the dipole, however, in a real emergency situation not really that important....

In all, about 10 minutes work and using the existing coax cable.

Off course it would be better to have a spare coax and a more sturdy emergency dipole at hand.

Jan
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Old 18-10-2011, 05:31   #33
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Re: Emergency VHF Antenna Question

Hey Jan, I am just curious, did you read posts 12, 21 or 30 in this thread?
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Old 18-10-2011, 06:03   #34
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Re: Emergency VHF Antenna Question

One of the advantages of running my AIS from a seperate antenna mounted on the gantry at the back of the boat, is that I have a decent emergency antena already in position. I have a length of coax to connect from the VHF to the AIS antenna so that it is a simple solution.
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Old 18-10-2011, 06:11   #35
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Re: To Wotname: Emergency VHF Antenna Question

Hey sorry I skipped diagonally through them but YES I missed reply 30....sorry for that!
Yes it explains the same thing.
What the heck I only gave some more detail but I admit that I added unnecessarily to this thread.....

Won't do it again.....
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Old 18-10-2011, 07:59   #36
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Re: To Wotname: Emergency VHF Antenna Question

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Hey sorry I skipped diagonally through them but YES I missed reply 30....sorry for that!
Yes it explains the same thing.
What the heck I only gave some more detail but I admit that I added unnecessarily to this thread.....

Won't do it again.....
No need to apologize, I wasn't being critical of you or your post. Perhaps it is I who should apologize for not making that more clear.
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Old 18-10-2011, 08:37   #37
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Re: Emergency VHF Antenna Question

We carry a 3 piece 27' fiberglass whip for our SSB with antenna mounts already installed and extra cabling in case our rigging is lost. We also have two rail mounts installed for the emergency VHF whips kept onboard as well. It takes us less than 10 minutes to have the antennas switched and the radios up and running.
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Old 18-10-2011, 14:22   #38
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Re: Emergency VHF Antenna Question

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We carry a 3 piece 27' fiberglass whip for our SSB with antenna mounts already installed and extra cabling in case our rigging is lost. We also have two rail mounts installed for the emergency VHF whips kept onboard as well. It takes us less than 10 minutes to have the antennas switched and the radios up and running.
The good folks of this forum are always better prepared than the general population when the $hit hits the fan. Must be because when cruising you don't have the option of calling the local repair guy, combined with having both confidence and understanding of many varied disciplines involved with cruising, don't you think?
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Old 22-10-2011, 11:40   #39
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Re: Emergency VHF Antenna Question

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Lets say my antenna gets broken and all I have left is the coax...
If you are considering adding AIS, then mount the AIS antenna on the pushpit, where it will double as an emergency VHF antenna.
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Old 22-10-2011, 11:49   #40
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Re: Emergency VHF Antenna Question

Our boat has two antennas and two radios. Not sure why, the last owner did that but I like it. Each radio has a switch to switch between the mast top antenna and another one on the aft railing. I like backup systems. I don't know anything about how they work though so sorry. I only know how to use them.
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