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Cutting reciever wire bad idea?

Old 10-18-2006, 05:46 PM
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Machinegun21
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Default Cutting reciever wire bad idea?

is it a bad idea to cut the wire on your receiver? i need to take about 1 foot off of the receiver in order to get it to fit nicely. will doing this affect the range or the way it handles?

Thank you.......
Old 10-18-2006, 05:51 PM
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Ross Kean
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Default RE: Cutting reciever wire bad idea?

Very bad idea. You could significantly reduce range.!!

Ross
Old 10-18-2006, 05:54 PM
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RCKen
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Default RE: Cutting reciever wire bad idea?

That is a huge no-no. Cutting any length off will reduce the range of the receiver. It's designed to be a certain length (approx. 39) in order to operate properly. Leave the receiver wire at it's original length and let the extra trail out behind the plane. It won't hurt anything like that.

Ken
Old 10-18-2006, 06:11 PM
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Missileman
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Default RE: Cutting reciever wire bad idea?

The last reciever I bought came with a plastic spool to use for shortening the wire.
The instructions have you wind some of the wire on the spool being carefull not to overlap the wire.
Old 10-18-2006, 06:12 PM
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ramkitty
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Default RE: Cutting reciever wire bad idea?

by cutting the lenght of the wire you effectivly change the receive frequency of that antenna (shorter = higher freq)
usually antennas are in a length of submultiples of the frequency wavelength

wavelength = v/f where v is the velocity of propagation, for us its basically the speed of light or 3x10^8

wavelength = 3x10^8 / 72MHz = 4.16 meters
so using 1/4 wavelength it would be ~1 meter or 39"

if you were to shorten it by the 1 foot .69 meter you will have changed the frequency to
freqency = 3x10^8 / .68*4 = 110MHz

your best bet, if you must shorten it would be to try a deans antenna or to tape it to the bottom of the fuse in a wavy pattern (which would still reduce range but not as much)
Old 10-18-2006, 06:54 PM
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Default RE: Cutting reciever wire bad idea?

Do you like to watch model airplanes crash? This is the quickest way that I know of to be able to watch one. The bad part, is that it will be yours.

Bill, AMA 4720
WACO Brotherhood #1

Old 10-18-2006, 06:58 PM
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Machinegun21
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Default RE: Cutting reciever wire bad idea?

WOW! ok, yeah i found a spool to wrap the wire around. i probally was'nt going to cut it anyway either way i got figured out. thanks for all your help and especially ramkitty for that nice formula to calculate range.
Old 10-18-2006, 08:03 PM
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Dr1Driver
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Default RE: Cutting reciever wire bad idea?

STOP! I do NOT recommend winding the wire around anything. What you'll do is create a "loaded" RX antenna. When done properly, this MAY increase the receiving capability. When done wrong, it may drastically decrease it. Loaded antennas usually require a specific number of wraps on a specific size spool.

Please do as many have already suggested and simply let the wire hang off the back of your airplane.

Dr.1
Old 10-18-2006, 09:27 PM
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Default RE: Cutting reciever wire bad idea?

If you do not want to let the antenna hang out the end of the plane, Hayes has an 18" loaded antenna for about $4.00 http://www2.towerhobbies.com/cgi-bin...?&I=LXK822&P=7
Old 10-18-2006, 11:02 PM
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Cyclic Hardover
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Default RE: Cutting reciever wire bad idea?

Remember the movie "Major League?" It is very bad to drink Joe Boo's rum--very bad! You cut that antenna wire and a baseball bat is going to come out of nowhere and take out your plane.
Old 10-19-2006, 01:19 AM
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bigtim
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Default RE: Cutting reciever wire bad idea?

your plane will look as though it was shot down by 21 machine guns, just couldnt help myself.
listen to these people they are speaking the truth don't cut the wire!
Old 10-19-2006, 05:39 AM
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Dr1Driver
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Default RE: Cutting reciever wire bad idea?

Campy has a good suggestion. If you just MUST shorten the antenna, go with a commercially-made load.

Dr.1
Old 10-19-2006, 09:18 AM
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The Toolman
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Default RE: Cutting reciever wire bad idea?

Not so bad if you have Berg Receiver. This is from the Berg people themselves on their folder in RC Groups

Both the Berg 4 and 7 use the same basic technology. Both have pre-base loaded antennas. You can cut the antenna off any length you like and it will still work. The length of the antenna is directly proportional to range; cut it in half, the range is cut in half; quarter length equals quarter range, etc. Figure about a mile range for a full length antenna as a starting point.

Adding another base loaded antenna might or might not increase the range of a shorter antenna length, but in any case it will not hurt.

Bernie


http://www.rcgroups.com/forums/showthread.php?t=568739

Ronnie-The Toolman
Old 10-19-2006, 10:30 AM
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Rodney
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Default RE: Cutting reciever wire bad idea?

Modifying the antenna length, either way, will most probably decrease your range. Some receivers are more tolerant of this than others. for instance, FMA M5 will not change tuning but will loose range with a shortened antenna but many electric park flyers use the M5 becuase of it's high tolerance to shortening the antenna. Even the commercial shortened antenna will reduce the range but; we are furtunate in that most of the better receivers still have adequate range with the commercial shortened antena. Check out some of RCCam's experiments on changing antenna lengths for good info on the true facts on effects of changing antenna lengths. His experiments were done using good test equipment by someone who knows what he is doing.
Old 10-19-2006, 01:01 PM
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RVM
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Default RE: Cutting reciever wire bad idea?

Don't cut it. Don't wrap it. Let it hang out the back.
Old 10-19-2006, 05:29 PM
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Machinegun21
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Default RE: Cutting reciever wire bad idea?

ok, thanks.
Old 10-19-2006, 06:28 PM
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NCIS
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Default RE: Cutting reciever wire bad idea?

Use an inside antenna fuselage tube and put the wire through it. Then what ever is left over just pull out the end of the tube and fold back. It doesn't touch the other part of the antenna and works great. Before some of you guys say I'm wrong, I want to tell you all 10 of my flyable planes are setup this way and they have never gone out of range or had any glitches. I learned this from an old-timer and have done it ever since!!!

Gibbs
Old 10-20-2006, 11:52 AM
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Rodney
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Default RE: Cutting reciever wire bad idea?

NCIS, you may be getting by when the folding back the antenna but only because the range is still good enough for you. If you check for maximum range, you will find that folding the antenna back definately cuts down the distance at which reception is still reliable.
Old 10-20-2006, 12:06 PM
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NCIS
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Default RE: Cutting reciever wire bad idea?

Rodney,

That may be true but I take my planes out so far that they are very small and only can get them back because I know which way I'm headed. I turn and it grows. Any further and I'd lose sight of them and these are large to giant size aircraft. One is an Aviation Models 30% Yak 54. Our field only allows you to go that far out in one direction. I do appreciate your feedback!

Gibbs
Old 10-21-2006, 05:22 PM
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chashint
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Default RE: Cutting reciever wire bad idea?

Twleve inches is to much remove. If you had asked about 1 or 2 inches my answer would have been different.
To recommend a solution to what you want to do I ask this question, is it possible to slip the antenna into a small flexible plastic tube and snake it back and forth inside the fuselage ? You will want the curves to have the biggest radius possible. Since 12" would have been sticking out I must assume that it is a small plane, being a small plane means it will be flown fairly close in, or at least with my eyesight that is what it would mean. Having the antenna less than fully extended will reduce the range somewhat, but we have a lot of range to spare, if the plane is small and flown fairly close in you should be good to go.
Unless an electrical engineer has published the instructions I do not recommend wrapping the wire around anything to create a coil. While it is possible to make a coil that will enhance the performance of the antenna it needs to be an engineered solution and it needs to be measured with test equipment to verify the design.

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