ORIGINAL: mmabc
I'm curious how this impacts a trainer slave setup? I learned on mode 4, but I don't want to teach anyone mode 4. I'll want the slave radio set to mode 2, and the master set to mode 4. Anyone know if I can do that?
It shouldn't. What pot is used to control what channel is encoded is simply a mechanical issue. In the old days as you say you needed to swap pot solder points because the channels were hard coded to a conduit. Nowadays the "swapping" is done electronically. As you remap the aileron to the left horizontal pot from the right (and vice versa for rudder), the encoder knows where to
receive the input from on a specific channel. So if aileron is assigned channel 1 by your manufacturer, channel 1 is encoded to the Tx from the preset stick and sent over RF to the Rx.
In a trainer setup, it is simply a matter of
which encoder is used to control the channels. If encoder A (the instructor) is used, the instructor's channel encoding is sent to the transmitting RF. If the student's encoder is used, that encoders mapping is sent over to the instructors RF deck. What sticks happen to be used on each transmitter is strictly a local thing. The Rx knows nothing about that nor does it care. It just reads "Ch 1, +2.3V - go"... so to speak.
One other question. I was looking on craigslist yesterday. It might interesting to buy out someone with an upgraded trainer, plus a radio and other accessories I need. I saw a bunch of folks with 72Mhz radios. What's the story on that? I see the new ones are 2.4Ghz. That was one of the final straws that took me out of RC when they changed the frequencies and I would have to replace my $500 radio. Are the 72Mhz radios still in use legitimately?
It might just be me but I wouldn't buy someone else's trainer unless I'd seen it fly and probably knew the person selling it. I also wouldn't recommend buying used 72 MHz equipment today (unless there is a specific reason like wanting to convert old well build joy stick radios to modern encoders and 2.4 decks). New 2.4 radio equipment is just so reasonably priced today that buying used 72 is not only a
no warrantee proposition but it also is investing in deprecated equipment. You can spend as little as $50 on a new 4-5 channel 2.4 Tx. Receivers and servos are typically bought separately in any case so there is no huge added benefit from buying a complete radio system today. With ~$250-350, a new 7 or 8 channel Tx can be bought. While it is not necessary at first, it quickly becomes useful to have a few extra channels and the associated programming ability of those radios. For a lower start up cost, a 5-6 channel Tx is the way to go.
That said, 72 MHz is a legal band today but the frequency separation is narrower than before the days of PCM (which was typically also 72 just encoded in a "digital" way). In order for any Tx and Rx to be AMA or MAAC legal on the 72 MHz band, they have to be "narrow band" compliant. In most cases, it is easier to use a modern inexpensive 2.4 band RF deck even if one wants to continue using older encoder and stick/switch Transmitters (e..g, Kraft, ProLine and the like).
David