Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: lakeshore on September 28, 2012, 05:10:36 pm
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Anyone know the correct aerial wire length for a Futaba FP-R122JE 27mhz am receiver, got this one from a model car friend and the wire has definetly been shortened as its only 12 inches long.
Conflicting email reports from both Futaba and Ripmax on the standard factory length of the wire one says 44 inches and the other says 22 inches, as its intended for boat use range would be an issue.
Rather bewildered
John.
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30 inches should be OK for 27mhz boat use.
Colin
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Quote from Futaba Tech Dept
The 44 inch length is for boat use max range and the 22 inch length is for car use short range.
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It's all down to fractions of the wavelength %) 44" in a model boat is ridiculous {-)
I think the max. I've had vertical from a my boats is around 12". Range is not an issue, your eyesight will give out before you reach max. range....
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I see it does seem rather a lot I know, but there again do they not tell you not to cut the aerial lead because of range issues and glitching.
I have two of these receivers both on 27mhz am. 1 has a lead cut to 12 inches and a range before glitching of 50 to 70 feet obviously cut for car use and the other is brand new in the box with an aerial length of 39 inches uncut and with a range without glitching of 350 plus feet as it says in the book.
The point is that Futaba send these out with full range aerial leads fitted and I only contacted Futaba to find out what to replace the cut aerial length with.
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.....and the other is brand new in the box with an aerial length of 39 inches uncut ......
I know for 35MHz, 40/41MHz and 72MHz - the antenna lengths are all the same at 1metre, (there's a small amount in the case that usually reduces the exposed portion to 39"), and the Rx circuits are tuned to that length for max reception, (what you're showing as range :-)))
I see no reason for reducing the length of an antenna below it's supplied length - unless you're using a wire whip antenna to replace the 'cut off' length.
It's easy enough to install a full length antenna in a boat by running it around the hull under the deck - and even easier on a yacht by running it up the backstay :-))
Mark.