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Lun Su Aerial Length

R

rockonpete

Newbie
Joined
Jun 13, 2011
Messages
4
Location
UK
Hi. I have just aquired a developed Rock Climber but still with the stock Lun Su TX and RX. Close range performance is perfect but there is currently a severe range limitation and I need to eliminate the RX aerial length as a contributing factor. My most accurate measurement is 320mm in the support tube plus 90mm to the TX making 410mm in all (16"). Does this correspond to what should be there with the Lun Sun LS-202-R receiver? I have isolated the originals and slaved in replacement servos and the ESC with an independent clean RX power supply to no effect so the problem is in the TX or RX system. Next step is to try new crystals and then it may get more expensive I fear. Confirmation of the aerial length question would be much appreciated along the way. Thanks for any help with this.
 
New crystals aren't gonna fix the short range problem. Crystals change the frequency that is transmitted, so if you're crawling with someone that has the same crystals, you would get interference...so crystals would fix that. I'm not sure what kind of range you're looking to get. I've never had the urge to be more than 10 or so feet from my rig so I can see potential binds it could get in, but you should do some research into possibly getting a 2.4ghz rx/tx setup.
 
Thanks to you both and I fully appreciate the superiority of 2.4GHz but I also haven't got over the novelty of the mixed steering that the original kit offers. The reason to try new crystals is in case I have a damaged/degraded crystal and they are a cheap next step. Presently range beyond 15ft can be unpredictable and sometimes less. I am pretty sure it is a RX problem and forums seem to agree that RX aerial length is fairly critical to performance at this frequency. So how about a confirmatory aerial length measurement from a fellow 27MHz dinosaur?
 
I've got 20" on my rx. (500mm). However, Over 15ft away has always been an issue. But I got all the bugs out within 15ft through wire placement.
 
Thanks Jackalope - that's a significant 4" difference (25%). Is your RX the stock Lan Su LS-202-R?

I read an interesting assessment of the effects of aerial length at http://rc-cam.com/ant_exp.htm. Although the practical experiments were done on a 72MHz receiver with stock 40" antenna, the effect of shortening by 8" (20%) was a signal loss of about 3dB or 50% strength. The inverse square law converts this to a range reduction to a quarter of what it was. The article also investigated the effects of coiling the antenna wire.

The link is one of hundreds on a very informative database maintained by Alan Tong in New Zealand and I would commend his link to all: http://homepages.ihug.co.nz/~atong/.

I would appreciate a couple more original kit owner confirmations of untrimmed aerial wire length then I can move on. Thanks for your patience.
 
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