yuvallahav

Hello all.

I need some help with my new airplane radio receiver.

I have an old airplane, and the wirering for the radio goes as folows:

1 radio receiver, has 5 slots in it, 1 for the plug from the swith, which connects to the battery on the other end, and 4 for the different channels.

On my new airplane which I just finished building, I bought a couple of different radio units, but both of them have 4 slots, one for each of the channels.

My question is, with these type of radio raceivers, where and how do I connect the switch/battery part?



If more information is needed, let me know and I will add it up, and not, please find the time to reply my post, as I am near compleation of the airplane, and would love to take it out on a test flight ASAP.



Thanks.



Yuval Lahav.

Rome, Italy.

alan0899

G'day Yuval,
I sure, one of the slots, will say, servo/battery, this where you plug in your lead from the switch, or use a "Y" lead, & plug a servo into one side & the lead from the switch into the other side, then plug it into the appropriate slot for that servo, it will still work, try it.
You can always try it by plugging the switch lead into a servo slot, turn it on & make sure the receiver works.

yuvallahav

Ahhh... if it was that simple... but alas, it's not.
I have no servo/battery slot what so ever.
What I do have are 4 slots saying "chan1", "chan2" and so forth, and before I go to fry my radio with trying to plug the switch plug to one of these slots (since I need only 3 channels on this specific airplan), I though I'd ask, just to be sure, and maybe have someone to blame if I do fry my radio by doing so

Thanks.

Yuval Lahav.

Dan767

My Feedback: (19)

It makes no difference which channel you plug the battery into. Not knowing which brand of radio you are using, I'll use Futaba as an example because that is what I am most familar with. Channel 1 is aileron Channel two is elevator Channel 3 is throttle four is rudder. If I needed only three of these slots, such as an electric that has an esc, then I would plug the esc into channel three and the rudder and aileron into the appropriate channels. Since you are using only three, plug the servos into the correct slots, then plug you switch harness into the remaining unused slot. When you have an airplane that needs all four slots for control, "Y" the battery switch with any of the servos. Hope this helps and makes sense.

yuvallahav

That made perfect sense, since I don't have much exp with radio, but I do have some exp with electronics, now my mind is at rest, and I will do as told (tonight, after I get back from work, after I put the kids to bed, after I get some food in me, after I answer to all of my wifes questions about my day, after I fix all that needs fixing around the house...), and will report tomorow on the outcome of the test...

Thanks again.

Yuval Lahav.

cheddar-caveman

It doesn't matter which slot you plug your battery into as all slots have a +ve and -ve terminal. Just make sure you don't use one that you need for a servo and that you plug the plug in the right way!

yuvallahav

Well... I've done the tests, and the results are in...
Both of the receivers seems to be connected correctly, meaning the battery is connected to one of the slots (4th, since I will be using the first 3), and when I connect it all and switch on the battery, the servos make their first connection jiggle (couldn't find a better name...), but it would seem that no matter what I do, I can not control them... the frequency is right (I even switched the oscillators on both the receiver and transmitter to a pair I had before) but nothing happens, no response from the receiver side... when I reconnect my old receiver (that came with the Futaba kit I had), it all works fine, with these 2 new receivers, I get no response, no matter what I do...
What could be the problem?

Thanks.

Yuval Lahav.

cheddar-caveman

You say "both of the receivers". Have you got two receivers in the plane???
It sounds as though you are mixing channels. Tx on one frequency, and Rx on another?
Are your new receivers compatible with your Tx?
Are they operating in the same band even? Not 40Mhz by mistake?
Are they single/double conversion with incorrect xtals installed?

yuvallahav

mmm.. many things I didn't understand (since I'm new to radio, used my store bought kit up to now), but some I do, and here are the clarifications:
I don't use 2 receivers, but I have 2 new receivers, and tried each in turn, not together.
one of the receiver has 72Mhz written on it, and my transmitter runs on 72.9something (I'm at work, so can't give you the exact details at the moment, but will when I get home), and the second receiver came with an oscillator of its own for my transmitter, which I installed on it, but again, nothing happened. I do have some mix buttons on my transmitter, but I didn't think about playing around with them, but I sure will tonight...
I'm sorry for all the confusion, but I'm new to this... I'm sure that with time I will be able to input a more accurate and useful information, but I'd like to thank you all for trying to help me out

Yuval Lahav.

cheddar-caveman

Hi Yuval.
OK, we don't use 72Mhz here in England, always 35Mhz, but the equipment is basically the same.
Very basic I know but first you must have both Tx and Rx on the same frequency as I am sure you know. I believe the 72Mhz channels go from 11 to 60 so if your transmitter is on channel 55 then obviously your receiver must be on channel 55 as well.
There are two types of receiver out there and these are called single and dual or double "conversion". This simply defines the way the receiver decodes the signal from the transmitter, but these two receivers need different crystals (Xtals) I think you call then oscillators, to operate on the same frequency - the Xtals are NOT COMPATIBLE.
I'll monitor this posting again later on when you've had a chance to go home and check your equipment.
Have a nice day!

yuvallahav

Thanks for the info, I will sure check the things I have on hand when I'll be home tonight, and more over, I will start using Tx (transmitter?), and Rx (receiver) for better hobby lingo, and yes, the oscillator is the crystal, as the crystal reside inside an electrical component called an oscillator (I wouldn't know this but as my father has a company that imports and export and design custom made electrical components, he lectured me about it one day...).
Now... about the channels, could you expend a little bit more on that? I always thought a (for example) a 72Mhz crystal on the Tx will work with a 72Mhz crystal on the Rx, but it would seem there is the channel element I'm not aware of... how can I know what channel my Tx and Rx are on, without buying a small laboratory? if it's possible at all of course, without clear documentation of the Tx I have the different Rxers... and is there a way to play around with these channels to make fit what now seems not to work?

Thanks.

Yuval Lahav.

P.S.
I just though about it, since my father's company stock a ridicules amount of oscillators, what are the chances of getting him to ship (we live in different countries) me some, that would pair up correctly... I simply don't have the right type of knowledge to know what to ask, but if I put the question to him, I'm sure he will know what I need... it's his job after all...

yuvallahav

Ok, a small update to my last message, just to clear things up...
It would seem, after a chat with my father, that an oscillator is a component which the major part of is the actual crystal, and the thing we use on the radios are just the crystals, and not an oscillator, as I thought. So here, I can admit when I make a fool of my self.
But atleast now I know better, and also I was told by my father that as long as I can find out what is the specs of one of my crystals (on the Rx or the Tx), he could send me the correct crystal for the other part, which can be nice, money saved, no hassle, and my wife will be pleased by me not spending more money on e-bay on crystals that don't work simply because I don't know what I'm doing

Yuval Lahav.

cheddar-caveman

OK Yuval. Your 72Mhz "band" is divided up into 50 different "channels", each controlled by a "crystal" in your equipment.

Your crystals should look like this :



This picture is for 40Mhz crystals but your will look similar but will say a channel number between 11 and 60 on one side, and a frequency of between 72.010 and 72.990 on the other.

Have a look at your Tx and Rx crystals. They must both be for the same channel.

cheddar-caveman

Glad your Father can help you out. However, make sure he can supply a "compatible" crystal. A lot of equipment manufacturers make their crystal unique to their equipment and you HAVE to use their crystals.

Yes, an oscillator is a circuit built into your transmitter and receiver and it does just that - it oscillates at millions of times a second, and the number of oscillations it does in a second is controlled by the crystal. This is why you must have the same frequency crystal in bot Tx and Rx or else the canot communicate with each other.

yuvallahav

I know this would sound stupid, but do I have some play, if any, with the accuracy of the frequency? meaning if one crystals is 72.010 and the other is 72.990 (I took the extremes of the ends), but they are the same channel, will that work? asking hypothetical...

Yuval Lahav.

cheddar-caveman

NO! You have NO CONTROL over the frequency, other than by changing the crystal. That is what the crystal does. It "locks" your Tx and Rx to the frequency stated on the crystal.

The reason for this is so that you, and everybody else, knows EXACTLY what frequency you are on and can therefore select a different channel/frequency from you so that you don't interfere with each other.

No they are NOT the same "channel" 72.010 is channel 11 I believe while 72.990 is channel 60.

yuvallahav

I see... thanks! I have some info to work on now, and I will see what I can come up with when I get my Tx and Rx at hand, later on today

Thanks!

yuvallahav

Finally, the mystery is solved!!
Well, after a night of farther examination of the equipment I hold, it would seem the problem is very simple, but I didn't know it since I didn't have the documentation of the extra two Rx's I had laying around.
It would seem my Tx is an AM transmitter, and except for the original Rx that came with the Tx, the other two are FM Rx's, which of course, as I would imagine (and imagine is the only option I have, lacking the actual knowledge) would prevent my Tx communicating with my Rx's... even though the frequency and channel on both Rx and Tx crystals are the same... well, live and learn, is what I say, oh, and have a good magnifying glass and google on hand, to find out the specs of your hardware...

Thanks again, I'm sure we all learned a good lesson in this thread...

Yuval Lahav.

cheddar-caveman

Hi again Yuval. I have to say I didn't even think of asking about AM/FM! I didn't know people still used AM! Glad your issue is resolved, and I hope you can get the required equipment to get flying.
Happy landings
CCM

yuvallahav

Well, the Tx and the Rx I have were bought about 3 years ago, in Israel (although I live in Italy these past 3 years), by my wife's father as a wedding gift for me, along with my first RC airplane (balsa kit for construction, he wanted to get me a nice wrist watch, but hey, you gotta follow your dreams, and I simply can't stand the feel of a watch on my hand, so I asked for it, and he actually went and got it for me, and said it was the best idea ever, since he likes seeing a man who takes the time to follow his childhood dreams), so to make a long story short, I didn't know they don't use AM radios these days.
But don't worry about it, I already went and found me a nice new FM 4 channel Futaba radio on e-bay, and it should arrive any day now, and it will be used, along with my now usable, FM Rx's, on my new airplane which I'm just about to finish building...
By the way, if we are already on the subject, it would seem that balsa construction airplane kits are a dying breed in Italy, since I got the last box in the shop, and they said they will not get more of that type, since no one buys these kits these days, people like to come in, buy a plane, snap on the wings and go flying... And I always though, and still do, that building the plane yourself is half or more of the fun.

Thanks again for all the help.

Yuval Lahav.