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04-17-2007, 04:11 PM
#3
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RE: Berg receiver with Futaba transmitter. Low channel?
[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJSP9&P=0]Futaba Rx.[/link]
In the Tech notes.
In the Tech notes.
04-18-2007, 12:01 PM
#5
RE: Berg receiver with Futaba transmitter. Low channel?
It's there Rodney.
NOTES FROM OUR TECH DEPARTMENT
This is an R156F 6-Channel 72MHz FM Receiver "Without Crystal" from Futaba.
It is NOT suggested to go below channel 16
with these receivers as you may experience interference.
NOTES FROM OUR TECH DEPARTMENT
This is an R156F 6-Channel 72MHz FM Receiver "Without Crystal" from Futaba.
It is NOT suggested to go below channel 16
with these receivers as you may experience interference.
04-18-2007, 12:50 PM
#6
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RE: Berg receiver with Futaba transmitter. Low channel?
ORIGINAL: Rodney
Where did you find that warning from Futaba? Technically, there is no reason for such warning.
Where did you find that warning from Futaba? Technically, there is no reason for such warning.
The problem is that a receive frequency that is 455KHz above the crystal frequency will also produce the 455KHz signal (receive frequency - crystal frequency = 455KHz).
This means that any signal that is 910KHz above the intended receive frequency (455 x 2 = 910) could cause interference. As long as you stay above CH15, there is no rc channel within this frequency range. On channels 11-15, there is a possibility of interference from the upper channels 56-60.
The upper channles are 910KHz from the lower channels, which places the interference in between the lower channels in the receiver, but close enough to cause a possible loss of control.
The Castle Creations Berg receivers are available on all channels 11-60, possibly because they are using DSP (digital signal processor) to filter out the interference, or they may not be using the 455KHz frequency. A DSP is quite capable of operating directly at the 10.7MHz frequency used as the first stage in a dual-conversion receiver.
04-18-2007, 01:29 PM
#7
RE: Berg receiver with Futaba transmitter. Low channel?
Just spent some time browsing the notes in Tower and it appears to be isolated to the single conversion FM RX's. The AM's carry no such warnings and neither do any of the dual conversion RX's.
04-18-2007, 03:26 PM
#8
Senior Member
RE: Berg receiver with Futaba transmitter. Low channel?
Okay, I see what you mean. If they had said " due to interferance from 3rd order harmonic distortion", I would have known why. It is not that the receiver does not work properly at the lower channels, it is because they are more subject to interferance due to 3rd order harmonics from other transmitters. Back in the days before FM was common, lots of clubs had charts set up to warn people of this problem. On single conversion receivers, there are a few other channels that can also be adversly effected, it is not limited to the below channel 16.
04-18-2007, 04:41 PM
#9
Senior Member
RE: Berg receiver with Futaba transmitter. Low channel?
ORIGINAL: Backwing I'm trying to find a small receiver for my foamie, but my problem seems to be that my transmitter is on channel 12. I barely avoided a crash with a Hitec 055 receiver, and Futaba warns against using anything below channel 16 on one of their micro receivers. JR deosn't even produce anything below 15. Has anyone used the Berg 7 ch. on frequencies this low? Was their any kind of interference?
Regards
Alan T.
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