RE: [Paddlewise] Boosting handheld VHF range

I suspect you would actually decrease your signal due to the significant
losses RG174 introduces. That assumes it will fly!

cya

> -----Original Message-----
> From: owner-paddlewise_at_lists.intelenet.net
> [mailto:owner-paddlewise_at_lists.intelenet.net]On Behalf Of 
> Steve Jernigan
> Sent: Friday, January 22, 1999 1:48 PM
> To: Kenneth Cooperstein; paddlewise
> Subject: Re: [Paddlewise] Boosting handheld VHF range
> 
> 
> At 05:47 PM 1/21/99 -0500, Kenneth Cooperstein wrote:
> >I have an Apelco 510 5w. handheld VHF radio that I use on my 
> sailboat.
> >No one can hear me even 3 miles away unless I climb onto my cabintop.
> >
> >I can boost the range by using a 4' base-loaded s.s. whip 
> antenna (3 db)
> >at the masthead, which is the standard solution.  However, 
> the folks at
> >Raytheon told me that I would do almost as well by just mounting the
> >whip on the rail, because that would get me almost to the 
> limit of what
> >5w will do with a 3db antenna.  Although Raytheon wouldn't 
> quantify the
> >range, they felt that it would at least triple -- going from 
> the rubber
> >ducky in the cockpit to the whip on the rail.
> >
> >I am considering bringing the whip antenna along on a paddle, in the
> >belief that if I need greater range, switching to the whip 
> (handheld or
> >on a stick) will greatly increase my range.  Anyone know if this will
> >work?
> >
> >Ken Cooperstein
> 
> Hi Ken et al!
> Yes, you can use your whip from your boat, however, I do not 
> believe that
> would help all that much. The real problem lies in the fact 
> that normally
> VHF radio signals only travel in a straight line, much like a 
> flashlight
> beam. When you are sitting in a kayak with your nose only a 
> couple of feet
> above the water your horizon is quite close, probably only a 
> mile or so.
> Even less if you are in the trough of a wave. When you mount 
> your antenna
> at the masthead of a sail boat, you have effectively 
> increased the horizon
> the antenna can see. I hope no one minds, but I have included 
> a couple of
> small attachments to illustrate this. If you refer to figure 1, I have
> sketched this, greatly exaggerating the curvature for the purposes of
> illustration. (please, I know my artwork sucks . . .)
> Anyway, what you really need is a way to get your antenna up 
> in the air a
> bit. I will present a method to make a very simple antenna 
> and antenna mast
> that will allow you to elevate your radiation point an 
> arbitrary distance
> above the waves (~18 ft in my illustration).
> Refer to figure 1 again. Visit your local electronics 
> junkyard (or Radio
> Shack if nothing else), and find a ~25ft length of RG48 or 
> preferably RG174
> (thinner and more flexible) 50ohm coaxial cable with a 
> connector on one end
> that matches the one on your radio (BNC is common). Carefully 
> strip back
> about 18in of the outer jacket, and double the braided shield 
> back over
> itself to expose 17.75in of the inner conductor. Wrap a bit 
> of electrical
> tape around it to hold things in place. Visit a kite store or 
> the like and
> get 6 pieces of fiberglass tubing 36 inch long by 1/2in OD 
> (figure 2). Size
> is not real critical, consider your requirements for stowing 
> it on your
> boat. Also get a length of the next larger size to make 
> coupling ferrules.
> The OD if the smaller tubing should be a snug fit into the ID of the
> ferrule. Cut an appropriate number of ferrules with a very 
> fine hacksaw,
> and superglue a ferrule onto one end of the 36in lengths. 6 
> of these as I
> have illustrated, fitted together, will be about 18ft long, and stiff
> enough that you can hold it straight up without excessive 
> flex. Obviously,
> change any dimension to suit. Next, slide the prepared end of 
> your coax
> into the tubing as illustrated in figure 2, and use epoxy or 
> something in
> the uphill end to hold it in place. You should then be able 
> to separate the
> sections starting from the top, and fold the entire thing up 
> like a tent
> pole. The 17.75in antenna length should be OK for a 160MHz 
> marine radio,
> but if you wish, you can use the following procedure to tune 
> it before you
> permanently fix the upper end in place. Have a friend with 
> another radio
> drive off down the beach until you can barely hear each 
> others signals.
> Slide the braid back or forward to change the length of exposed center
> conductor in ~1/4in increments until you find the point where 
> you have the
> best signal. (do this with the cable inside of the tubing) 
> Your bud might
> have to move further away as you tune the antenna; you want 
> to just be able
> to copy each other. Admittedly, this is a rather low tech 
> approach, but I'm
> sure you will find it a vast improvement over the ol' ducky!
> Feel free to contact me if you need more info! ByeBye! Steve J. KG0MB
> 
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