Insulated Backstay
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I'm this >||< close to buying a cruising sailboat (a Westsail 32) and can't
seem to find any info/detail on the recommended length for an HF (insulated) backstay antenna. I thought I'd rememberd this topic being discussed in the maillist before but I've searched the archives and nothing pops up. Since I know nothing about them I thought I'd ask if anyone has any experience/advice/tips/suggestions/pointers/websites concerning insulated backstay antennas? Thanks, Mike K5PU _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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If you've got a ground to the seawater, end-feeding anything up to about 5/8
wavelengths at the operating frequency works FB. Assuming you have an aluminum mast, you'll have significant directivity on the higher bands where the mast will act as a reflector. It'll work where the antenna is longer than 5/8 wave, but you'll start getting significant high-angle radiation. You can also string a simple center-fed half-wave antenna if you want and have the height. Run the feeder over to the mast and anchor it there if you can avoid interfering with the sail operations. Then run it down the mast to the rig. My experience is with larger vessels. From what I hear about recreational sailboats is that you'd better have everything you need, right down to the coax connectors and insulators on hand before you buy the sailboat. That's because sailboats have a reputation of absorbing every dime in your bank account right down to the minimum needed for franks and beans to eat three times a day...and some sailboat owners I've met don't even eat beans regularly <G>. Ron AC7AC -----Original Message----- I'm this >||< close to buying a cruising sailboat (a Westsail 32) and can't seem to find any info/detail on the recommended length for an HF (insulated) backstay antenna. I thought I'd rememberd this topic being discussed in the maillist before but I've searched the archives and nothing pops up. Since I know nothing about them I thought I'd ask if anyone has any experience/advice/tips/suggestions/pointers/websites concerning insulated backstay antennas? Thanks, Mike K5PU _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Mike,
As past comm officer and board member of the Pacific Cup Y.C. I have had occasion to rig about 10 offshore race boats for SSB ops (follow the action in this years race at SF_to_Hawii_race_underway <http://www.pacificcup.org/> ) . They have ranged in size from 24 ft to 50 ft. The typical number you see for a backstay or other vertical on a small vessel is 21' to 23'. This is chosen to avoid 1/2 wave resonance on marine ssb frequencies (located typically just above and below the ham bands). This number is recommended by many auto tuners so that the feed point impedance doesn't approach several thousand ohms (a 1/2 wave at resonance) leading to several hundreds of volts at the feed point (assuming a 100+ watt rig) and possible breakdown within the tuner. Refer to the SGC 230 manual and I believe the ICOM manuals as well. Having used the above dimensions on many occasions my experience has been that they work well on the marine frequencies as well as amatuer frequencies from 80 MHz (4Mhz SSB) up to 28 MHz. Of course that wonderful ground plane is a huge help in making contacts from the deck of a little boat all over the planet. The other side of the equation is getting a real good ground connection. There is literature as well about technques that can be used that don't involve drilling through and adding extra weight or drag to the hull via an extenal bronze plate. If you have any other questions feel free to ask. brian n6iz >-----Original Message----- >I'm this >||< close to buying a cruising sailboat (a Westsail 32) and can't >seem to find any info/detail on the recommended length for an HF (insulated) >backstay antenna. > >I thought I'd rememberd this topic being discussed in the maillist before >but I've searched the archives and nothing pops up. > >Since I know nothing about them I thought I'd ask if anyone has any >experience/advice/tips/suggestions/pointers/websites concerning insulated >backstay antennas? > >Thanks, >Mike K5PU > > >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com > > > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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