JR receiver antennae length - Page 2 - RCCanada - Canada Radio Controlled Hobby Forum
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Old 02-04-2010, 02:00 PM   #11
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Re: JR receiver antennae length

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...right 39" is a 1/4 wave then .... so how would an 1/8 of wave perform?

edit: re-read the OP ... 1/2" short, not antenna cut in half. Most likely a non-issue.

When all you've got is a hammer, every problem starts looking like nail!

Last edited by marcham; 02-04-2010 at 02:07 PM.
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Old 02-04-2010, 02:05 PM   #12
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Re: JR receiver antennae length

Guys, practically speaking, 1/2 " is not going to affect the range or performance of our receivers.

Andrew Coholic -MAAC #26287L

1/2A to giant scale, IMAC, SAM, R/C sport, turbine jets, Heli's...
if its got a wing or two and an engine - I like it!
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Old 02-04-2010, 02:19 PM   #13
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Re: JR receiver antennae length

It is a fact that our Tx/Rx operate on 1/4 wave length and there is a formula used to calculate the exact antenna length for a specific frequency. I forgot the formula but it is available on some web sites.

I once did the calculations of all of our frequencies on the 72 band to measure the exact length of the antenna for each frequency. The total difference between channel 11 and channel 60 is about 3/4 on an inch. Given that our signal is able to control and object (plane) at a distance of one (1) mile or 5,280 feet 3/4 on an inch would translate to about 67 feet. Since we (exception taken ) operate our planes (fly them) at about 3,000 feet or less within good field of vision then, 67 feet is really negligeable.

39 inches is close enough to one meter which is really an arbitrary decision for length.

To my knowledge, crystal swapping is nothing more than brand name caprice. I had a great debate on the net a long time ago about this issue and no one proved me wrong to date. If crystal swap was a real issue then I believe that FCC would have ordered the soldering of crystals a long time ago and would have banned synthetisers,

I still look forward to expert comments on this one.

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Old 02-05-2010, 10:16 AM   #14
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Re: JR receiver antennae length

when I was usind Deans antennas their instructions indicated to cut the original antenna off leaving between 4 - 6 inches left and then connect the base loaded antenna.....I doubt that 1/2" will matter at all taking this into consideration...
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Old 02-05-2010, 12:18 PM   #15
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Re: JR receiver antennae length

Some of my JR's come in at 36", others 38 and 39" (got a couple of "other brands" at 30"as well)

Never had a problem with any of them. The math is correct for 1/4 wave at 39". My gut and my experience says anything 36-39" should be OK
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