[quote]ORIGINAL: ptb
Although I don't doubt either you or Wz, this is not the way to try to clarify a question that a newbie might have. The channel number corresponds to a frequency number. The TX crystal is marked as TX crystal, the RX Crystal is marked as RX crystal, and the channel number that corresponds to a frequency number are the same. it does not matter if the crystal is TX or RX. That is non-arguably the bottom line. The number of the TX Crystal and the number on the RX crystal have to match for the system to work. Since the channel assignments in the US are a set of discreet frequencies, I can't see where a manufacturer would put a channel number AND a frequency numer on the TX crystal and a channel number and a DIFFERENT frequency number on the RX crystal.
I agree with Wz on the type of receivers used. Just not the delivery method of the information.
So when I go to the store, to buy crystals that match my transmitter frequncy, I should look in the back of my transmitter and find out the channel or the frequency, then using this chart I can determine the other half of the information... Remember that it is against FCC regulations to change Transmitter crystals by yourself. Only a licensed technician can change TX crystals. Changing a trasmitter module is not the same as changing a TX crystal. Just don't change the crystal itself.
72 MHz
For Model Aircraft Use ONLY
Channel No.
Frequency
11 72.01
12 72.03
13 72.05
14 72.07
15 72.09
16 72.11
17 72.13
18 72.15
19 72.17
20 72.19
21 72.21
22 72.23
23 72.25
24 72.27
25 72.29
26 72.31
27 72.33
28 72.35
29 72.37
30 72.39
31 72.41
32 72.43
33 72.45
34 72.47
35 72.49
36 72.51
37 72.53
38 72.55
39 72.57
40 72.59
41 72.61
42 72.63
43 72.65
44 72.67
45 72.69
46 72.71
47 72.73
48 72.75
49 72.77
50 72.79
51 72.81
52 72.83
53 72.85
54 72.87
55 72.89
56 72.91
57 72.93
58 72.95
59 72.97
60 72.99
Chart taken from here: [link]http://www.modelaircraft.org/events/frequencies.aspx[/link]
I understand the concept of "super heterodyne receiver", the differing frequencies and I know for a fact that those are the types of receivers used in our applications. But to tell a newbie to look for frequency X on the TX crystal and frequency Y on the RX crystal is just the wrong thing to do. Crystals are going to be marked with the frequencies (or channels) on the chart above ONLY. and only matching crystals will work.
Wz and Ptb have much more intimate knowledge of how RC systems work. Although interesting, I have no intention on reaching that level of knowledge. I have enough stuff in my brain between my hobbies and my career. What I can pick up along the way I consider it a bonus.
Rafael