RX problems; Newbie needs help
 

Hello,
Let me first say that this forum is awesome! I really appreciate all the help I've gotten from the good folks around here.

Now to my problem: I replaced the receiver in my Parkflyers Cessna 182 with a Hitech HFS-04MG FM negative shift. The original receiver was giving me problems and Parkflyers wasn't helping me get it replaced, so I figured I'd upgrade and get the Hitech.

I installed it into the Cessna, and when I plugged the crystal from the old RX everything started twitching like crazy. The servos do repond to stick input, but they are constantly twitching up a storm. Any ideas on what's going on? The old Parkflyers RX twitched a little, but nothing like this. Am I not supposed to swap crystals like that? I thought about getting a new crystal along with the new RX but I have no idea what channel my radio is transmitting on.
Any help will be greatly appreciated.
Thanks,
joel

RE: RX problems; Newbie needs help
 

I,ve no idea what your parkflyer electronics are but generally if you are going to mix brands of Tx and Rx's the following you will have to find out and match up: the Tx and Rx must be operating on the same band 27 Mhz, 72 Mhx or 49 Mhz. Some of these park flyers use the limited power 49 Mhz in the US. Next the Tx and Rx need to be capable of functioning on either AM, FM (PPM) or PCM modulation types. If FM then both the Tx and Rx must be capable of functioning on either positive or negative modulation shift. And finally both the Tx and Rx need to be on the same channel of the respective band.

You need to find out what channel your Tx is on, most crystals are imprinted with the actual frequency and you can refer to the AMA channel chart to find out what channel you are on. Some of these low cost park flyers do not interface very well with conventional equipment and yes its poor practice to intermix rx crystal brands, all combinations do not work. AM and FM Rx crystals are not interchangable, its always wise to buy a new crystal with a new rx of the same brand and appropriate to the model Rx you order.

John

RE: RX problems; Newbie needs help
 

Thanks for the info, John. I did match up all of the things you listed (band, frequency, channel, shift). My only conclusion is that the new Hitech TX doesn't like the old crystal, so I've ordered the matching Hitech crystal.

I didn't know about the AMA channel chart. I looked up my frequency and got my channel off of that. Nice tip.

Again, thanks for the info. I'm hoping the new crystal will do the trick.

Joel

RE: RX problems; Newbie needs help
 

there are exceptions... but for the most part, you need to use the crystal from the same brand as your Rx

RE: RX problems; Newbie needs help
 

heyz....wat if im usin the crystal from my MCU chip to connect up to my reciever...how do i match it with my transmitter?
is the brand still important?
how do u find the range of the receiver and transmitter??

im workin with PIC18F2431...so any recommandations for the Rx and Tx??

ok...im realli realli new at these...wat exactly are the channels on the transmitter for??
if i have four motors to control how many channels should i have for my Rx/Tx??