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Old Sep 07, 2006, 09:19 PM
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Antenna question

I have a 30cc homelite motor in a 48" boat. Do I have to run the RX antenna straight up outside the boat or can I run it straight inside the boat? If inside the boat how far away from the Gas motor should it be?
Thanks Dan
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Old Sep 07, 2006, 11:00 PM
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McAlester
Joined Nov 2004
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Dan,
It is not absolutely necessary to stand the antenna straight up. It can be run inside the hull. It's best to keep it as far as possible from any other wiring and the engine. Inside the hull antennas will produce less range than a 'stand up straight' type antenna will. That difference probably won't matter a great deal though. As with any installation, doing a range test is the way to find out your max range. Subtract a reasonable 'fudge factor' from that range for the 'usual' usable range to be on the safe side. From there, it's just a matter of personal preference.
- 'Doc
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Old Sep 08, 2006, 08:44 AM
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antenna question

LtDoc, i'm not one of your army recruits!
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Last edited by Mikedown; Sep 08, 2006 at 02:05 PM.
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Old Sep 08, 2006, 10:04 AM
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Hunt County, Texas
Joined Sep 2005
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Quote:
Originally Posted by retoabcr
LtDoc is correct on wrapping antenna inside boat and range area. What if the boat gets out of range, it can happen easily. Why not make it easy on your self and go straight up by running 1/8" plastic tubing and leave 2" extending out of top with bare wires showing. I take K & S brass tubing that is just a little bigger in size and put a hole thru top of hull and have a small block of wood to insert brass and epoxy it in. I use one rx for all the boats. I measure the full lenght of the manufacturers antenna wire and make another wire extra long so i can put a female spade clip on the new wire and have it run to where rx will be placed. I then cut rx wire and put a male spade clip and you know the rest. Where k & S and tubing come together, i shove as far as possible down and dab alittle goop on the antenna where the 2 met.Measure exactly the lenght of tubing and antenna and cut tubing off with antenna extending 2". If you want just dab alittle goop on the top of antenna for moisture. If this is something you can use, use it. Inside the boat at the base of antenna, just make sure no sharp edges arond to nick wire. Preferably i use piano wire with a loop on top so no eyes get poked out. Forgot, each manufacturer has a different antenna lenght.
Antenna length is not manufacturer-dependent, it's a function of wave length - which is, itself, a function of frequency. Your basic monopole antenna (which is what the wire is) should optimally have a length 1/4 that of the frequency to be received, & is easy enough to calculate. Presumably, manufacturers ship their receivers with antennas that are length-optimized for the radio frequency on which they operate. Appending to or cutting off from what was originally supplied is likely to result in degraded performance. Whether that degraded performance will be an issue for you largely depends on how close to the edge of the envelope you operate - for most of us, it's not a big problem.

JM
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Old Sep 08, 2006, 10:11 AM
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McAlester
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This is an example of doing things that sometimes have more uselessness than use, but help kill time while you are waiting for something to complete a model. If you are not 'equiped' to do something like this, and if you don't have more 'extra' time than you know what to do with, don't bother.

My curiosity is sometimes a terrible thing. Wanted to find out just what affect the receiver's antenna length had on range, have enough experience with radio stuff to have made most of the usual mistakes before, so just had to see for my self. Just happen to live next to a city park with a football field so even had the distances marked for me (sort of)! Set the boat on the bleachers at one end and tried out the controls from the other end of the field. Worked just fine. Cut antenna in half and did the same thing. Worked just fine as far as I could tell. So, cut the antenna in half again. Worked some of the time so figured that was as much shortening the receiver could stand if I didn't mind loosing control. If 'they' had marked the ball field correctly, I figured I had something like 100 yards of range with reliable control with a 1/4 of the original antenna's length, sort of, and since the pond where I do the sailing isn't a 100 yards across, I had it made! That with the antenna sticking almost completely straight up, some 'bends' in it though. Did the same thing with the antenna wrapped around the inside of the hull. Results not quite the same, lost maybe 25-30 yards without the antenna height (very rough estimate and sort of a large 'fudge factor' in that estimate).
Now for the 'facts'. The radio system was on 27 Mhz. I was doing this alone so more 'guess' as to controlability than absolute fact (depending on sight for the rudder and ears for the motor, neither all that dependable!). The 'straight up' was more like 'straight down', hung the antenna over the side of the boat (how do you stand an almost 3 foot antenna straight up, especially on a boat shorter than the antenna?). At that point I'd probably had done more walking than I had in a long time, and quit.
Please do not take any of the above as an absolute for radio range! Too many variable for it to work consistantly. But, it sure 'killed' some time and at least gave me an idea of what I could 'get away with', sort of. If you are smart, and have some 'extra' time, you'll do your own testing with your radio system and antenna placement to see what happens. <--- and THAT is the only thing in this post that's worth remembering!
- 'Doc
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Old Sep 08, 2006, 12:15 PM
3 Blades to the Wind
Shaun Hendricks's Avatar
Atascadero, California, United States
Joined Oct 2004
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Get a nice boat antenna. About $10-$20 and they have watertight mountings for the hull and look really spiffy!
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Old Sep 08, 2006, 01:59 PM
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antenna question

I don't talk to smart=alecks!
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