Need another 75 mhz FM receiver for older Airtonics MX-3

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golfmonke

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I have an old Airtronics 75 Mhz FM Radio, i'm getting another RC truck and want to use the same radio.

So I need another receiver that will work with this radio.

I've tried to find the original to buy another but can't find one.

Any idea of what I can buy that will work?

The radio is marked as 75.511, so I assume i'll have to get that crystal for whatever receiver I end up getting?
 

D3MON

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I have an old Airtronics 75 Mhz FM Radio, i'm getting another RC truck and want to use the same radio.

So I need another receiver that will work with this radio.

I've tried to find the original to buy another but can't find one.

Any idea of what I can buy that will work?

The radio is marked as 75.511, so I assume i'll have to get that crystal for whatever receiver I end up getting?
crystal type or synthesized?
its been awhile since looking back to the 75mhz but iirc (someone else please confirm or deny this) but should be able to swap back and forth between brand just need the same frequency of crystals.
for 27mhz anyway i would use HPI/TRX/Exceed/futaba controllers with multiple different brand escs, most of my running was close so i can't verify range capabilities in doing this.
 

golfmonke

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Don't know the difference between those types...

The receiver looks like it has a crystal sticking out the top of it.
Tried to pull it out, didn't come out.
Didn't want to force it in case it was permanently in there.

It has a 66 on the piece of plastic coming out of it. Not sure if that's anything to do with the frequency.
 

olds97_lss

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Novak made an adjustable (synthesized) receiver that had little dials to adjust the frequency instead of using crystals you took out. I had a couple of those back in the day when I had an MX3.

Took me a bit to find the name of the thing, Novak XXtra FM.

You check ebay?
https://www.ebay.com/itm/Airtronics-92236-3-Channel-FM-Receiver-75-mhz-with-75-670-Crystal/352721228662

This one looks like a familiar blue:
https://www.ebay.com/itm/Airtronics-92836-75MHz-FM-3-Channel-Micro-Reciever-For-M11-M8-MX-3/323869280270
 
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golfmonke

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According to the 2 page manual it lists 6 channels on 27mhz for the transmitter....

Also, how do you set the transmitter to the frequency you select on the receiver?
 

olds97_lss

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olds97_lss

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The MX3 was a 3 channel FM. I think you could buy it in 27mhz or 75mhz. The transmitter still had a crystal, you would adjust the dial on the novak to match the crystal you had in the transmitter.
 

D3MON

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Novak made an adjustable (synthesized) receiver that had little dials to adjust the frequency instead of using crystals you took out. I had a couple of those back in the day when I had an MX3.

Took me a bit to find the name of the thing, Novak XXtra FM.

You check ebay?
https://www.ebay.com/itm/Airtronics-92236-3-Channel-FM-Receiver-75-mhz-with-75-670-Crystal/352721228662

This one looks like a familiar blue:
https://www.ebay.com/itm/Airtronics-92836-75MHz-FM-3-Channel-Micro-Reciever-For-M11-M8-MX-3/323869280270
JR also makes them, XS3, and the XS3i i think.
@golfmonke if you would post a picture of the receiver to confirm synthesized or not that would be easier to know which you have.
 

golfmonke

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I updated my post with a second one that looked more familiar to what I had... am trying to remember from 15 years ago. lol! Pretty sure mine was blue like that one and it's listed as for the MX-3. This one: https://www.ebay.com/itm/Airtronics-92836-75MHz-FM-3-Channel-Micro-Reciever-For-M11-M8-MX-3/323869280270


As for the manual, only finding the 2 page deal:
https://www.competitionx.com/pdf/radio-equipment/airtronics-mx-3-manual.pdf
That's the exact receiver I have now.

Ya, it's old I know , bought it a long time ago, never got my RC working, and now want to get back into it.
 

golfmonke

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So, what your saying is I would need to pop open the transmitter and switch crystals when I want to switch vehicles?

Or I guess get the same frequency on the additional receiver(s)
 

D3MON

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So, what your saying is I would need to pop open the transmitter and switch crystals when I want to switch vehicles?
119503

there is a little slide out thing right where the arrow above is pointing the crystal will sit in, so just pull that straight out.
 

olds97_lss

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So, what your saying is I would need to pop open the transmitter and switch crystals when I want to switch vehicles?
Or you buy the same crystal for the second receiver, which is what I did. I don't recall having to "pop it open". Man, I can't remember. Though the crystal was exposed on the transmitter and you would just pull it out. Oh, it had a little cover over it:


That red tab above the trigger, pull the cap off and pull the crystal out.

Like I said though, back then, I only had a 2 or 3 vehicles, so I'd just buy the same crystal for both receivers.
 

golfmonke

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Sorry guys, didn't have the truck/receiver in front of me when I posted this. I had looked a while ago for the receiver and didn't find any.
But appears there are some on ebay now.

So then I just need to buy the same blue receiver and get the matching crystal frequency?
 

golfmonke

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Ah, that's where the crystal is! that's not too bad. I don't have that red tab though sticking out, the tag is inside with the crystal. Just assumed it was fixed inside somewhere when you mentioned.

But, I think it's probably easier to just use the same frequency in another receiver.
 
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golfmonke

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Haha, I guess posts are coming in as i'm typing, thanks guys!

And sure enough, there is "Crystal" in the 2 page manual in the diagram.
 

golfmonke

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While your here... and you had one, what does the "inp-adj" thing do just forward of the trigger?

I see it's something to do with the throttle, but no idea what.
 

olds97_lss

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Doesn't ring a bell... but there was a screw. Can't remember if it adjusted trigger tension or trigger position. Probably position. You could adjust it to be 50/50 (forward/brake movement) or 70/30 (forward/brake) which allowed you to get more servo travel for applying throttle, but shortened the throw for brake. Some vehicles t/b geometry kind of needed more movement for throttle.
 

D3MON

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Doesn't ring a bell... but there was a screw. Can't remember if it adjusted trigger tension or trigger position. Probably position. You could adjust it to be 50/50 (forward/brake movement) or 70/30 (forward/brake) which allowed you to get more servo travel for applying throttle, but shortened the throw for brake. Some vehicles t/b geometry kind of needed more movement for throttle.
looking at the manual think that is exactly what that is, (top of page 1).
my old traxxas tq2/tq3 controllers (27mhz) had that, could only use it on a few escs i had because it would not allow far enough to trigger the esc to go to reverse. nitros though it was pretty nice, one of mine i seem to remember having to have a slight drag brake for there to be enough movement to get the brakes to engage enough.
 

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