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Crystal change on 72 Mhz FM Transmitter.

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Old 10-03-2018, 05:48 PM
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partshunt
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Default Crystal change on 72 Mhz FM Transmitter.

Hi , am in the throws of purchasing an Airtronics Vangard RC System. I checked it out and it works fine, however, I find the receiver is 6 channel but the Transmitter is 4. I need a six channel transmitter and I have a chance to buy it but it runs on channel 14 FM and mine is channel 37 FM. Can I install the channel 37 crystal in the 6 channel radio in place of the Ch 14 crystal directly successful?? I do wish the crystal were closer to my 37 rather than ch 14, if it matters. Thank you in advance.
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Old 10-04-2018, 04:33 AM
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I had 3 Vanguards and all worked flawlessly for many years. I believe the crystal can be changed in the transmitter but definitely can be changed in the receiver. I think I still may have the manual and will check later today. The big question is going to be if you can still find crystals. You probably can find loads of Airtronics stuff at swap meets but will the people sell at a reasonable cost

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Old 10-04-2018, 05:04 AM
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Ok, here is what the manual says:

Your Vanguard transmitter and receiver feature plug-in crystals for ease of manufacture. The FM crystals “should not be changed” by the owner because realignment of the transmitter FM deviation is required following a crystal change. Failure to do this could cause the transmitter signal to be outside of the receivers pass band. This could cause loss of control and subsequent crash of your model. Do not change crystals! If a change of operating channel is desired, return Vanguard transmitter and receiver to Airtronics for the desired channel change

I am sure some people will tell you to go ahead and change the crystals. Remember, this is 30 year old equipment. If it was me, I would change the receiver crystal and do a long range check. I thought I still had a Vanguard transmitter and receiver and was just going to send to you, but looks like I pitched them.

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Old 10-04-2018, 11:46 AM
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Zeeb
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FCC regs require that any RF transmitting device must be serviced by a licensed technician with the equipment to test it for proper operation after servicing.
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Old 10-04-2018, 12:58 PM
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Smart move would be to have it properly serviced. Probably a smart move even if you didn't change frequency since it's a used system.

However, Range check is also your friend. Do a range check with the 4 channel to get a baseline. Then swap the crystal and see if it range checks the same distance. If it's less, get it properly serviced.

But my question is, with the price of the new systems these days, Can't you afford a radio on 2.4?
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Old 10-04-2018, 12:58 PM
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Originally Posted by Zeeb View Post
FCC regs require that any RF transmitting device must be serviced by a licensed technician with the equipment to test it for proper operation after servicing.
Check his location. I'm pretty sure the FCC has NO authority where he is.
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Old 10-05-2018, 01:03 AM
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Thank you all for your input. I figured it is not a simple matter to change crystal. It sounds to me like maybe I should go for something like a spaectrum or research a good modern radio on 2.4. I am in Canada so no FCC here but, we do have a Canadian Equivalent to baby sit us all Canucks. Used to be called Department of Transport (DOT). They changed the name to something else now. Thanks guys... Happy flying.
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Old 10-05-2018, 05:19 AM
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Electronic components don’t last forever and even wire and solder joints can go bad over time. Not to say you can’t use an old radio, but I would get checked before using. Someone probably still works on Airtronics

A new 6 channel Spektrum radio can be used with all the neat new bind and fly airplanes, helis and drones. Plus, you will get expo, multi memory and so many other advantages.

Good flying

bob

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