Hong Kong RC Sailplane Forum 香港滑翔機發燒友論壇

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PostPosted: 30 Jul 2005 09:24 pm 
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Joined: 26 Feb 2004 03:51 pm
Posts: 3624
Location: Hong Kong
Recently, I have very high casualty with my planes that use 40.9xx MHz.

My Electric Banana crashed two week ago (the plane destroyed, motor gone, this is a very costly crash!). The crash was obviously due to frequency jam. The plane was momentary lost control a few times before the crash. At that time I thought the interference were from the speed control (but funny this never happened before).

Last week, I flew my Trinity in Fei Ngo Shan which also used 40MHz. There were a few times that the plane momentary lost control, one time was even so close to a crash as I steered the plane for immediate landing after noticing the problem. Luckily, I plane missed the ground by only a meter before I regained control!

Today, I flew the Crazy Banana again using 40MHz. The wind was huge and there were lot of turbulence. As I steered my plane for landing, the plane suddenly lost control and flipped over, then it crashed into a hard rock and completely destroyed. Although the wind was so turbulence which may cause the plane to flip over, but funny, the plane's speed was high and the plane was still far away from the slope, so I should have one or two seconds to react, but it seems that plane didn't get my control input after the flip over. I highly suspect that there was a frequency jam.


Do any of you notice any problem with 40.9xxMHz? I was told PLA is using 40MHz with high power transmitter. Is that true? Anyone got a scanner to check it out for us?

Before finding out the true fact, I will put on hold flying my plane with 40.9xx MHz. So far I do not have any problem with my other planes using 35MHz and 72MHz.


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PostPosted: 31 Jul 2005 08:38 pm 
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Joined: 26 Feb 2004 05:31 pm
Posts: 741
Location: 沙田
未轉合法頻之前我用左 41.000 MHz 好耐﹐未試過有事﹐其實有懷疑可以用對講機收下﹐睇下有無干擾﹐另外既可能性就係發射 module 或接收有事。


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PostPosted: 01 Aug 2005 09:40 am 

Joined: 02 Aug 2004 11:34 am
Posts: 309
Agreed with YC. I had an experience with a Tx module. It started normally. Having operated for a period when the temperature getting warm, the problem came. The rx momentarily lost its response to the tx input, like what Stanley was saying. Problem gone with the tx module returned to manufacturer for fixing.
Besides, I don't exactly recall the time, maybe before Y2K, the union of Japan RC manufacturers and RC associations re-standardised the 40Mhz range for air-craft & surface models. They are in range of 40.XX0 while most of the 40Bands allowing in Enrope are 40.XX5. At 10khz separation is safe for most narrow band rX, whereas a 5Khz may cause the interference.


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PostPosted: 03 Aug 2005 02:21 am 

Joined: 15 Apr 2005 02:03 am
Posts: 46
Location: kc
:cry: 呢種情


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