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crystal question

Old 06-14-2004, 02:28 PM
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iliketobreakthings
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Default crystal question

me and my friend have the exact same frequency (am 26.995 mhz) cars so we cant drive together [:@]
he had an extra set of crysrtals (75.570 mhz) so he gave them to me.... for some reason i cant get them to work with my car when i plug them in the car wont move..... anyideas why???
i think maybe the new set of crystals might be fm?


[:'(]
Old 06-14-2004, 02:55 PM
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ekrcflyer
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Default RE: crystal question

First of all, I don't see how this set of crystals might work for you. The very reason for using the crystal is to STABILIZE the frequency (26.995 MHz or 75.570 MHz or other....). Even if your radio used second harmic, it should be 37.785 MHz (75.570 / 2)...

Second: there is no FM or AM "crystals"... AM, FM, PCM, etc. are the types of signal modulation - it is how the "control command" will be "encoded" to be carried in the air.

Most likley reasons for your problem:

1. Radio is not working,
2. Check the battery
3. Get right set of crystals (receiver side should EXACTLY match transmitter)....

Final question -why would you want to "drive the same car"?.... Just a question....

Good luck!
Old 06-14-2004, 03:00 PM
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iliketobreakthings
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Default RE: crystal question

our cars are not the same but the frequencys are....
Old 06-14-2004, 04:32 PM
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Tigger N. Bennie
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Default RE: crystal question

liketobreakthings,

From what you posted, it appears that the both of you are running channel 1, color code brown, with a 27MHz band radio. One of you probably needs to purchase another crystal set (channel 2-6) if the other is running on channel 1. Any other channels will probably not work with your radios and that includes 75.570 (channel 69 on the 75MHz band). Here is a link to a Radio Frequency Chart for "legal frequencies for R/C Aircraft, Boats, and Cars in the United States."

http://webpages.charter.net/rcfu/HelpsHints/RFC.html


ekrcflyer,

For your information, I own a Futaba T3PK and also has what Futaba calls an "AM Conversion Module." Guess what, it works with Channels 1-6. I've also tried to run two R/C cars with one radio in order to test which one accelerates faster.
Old 06-14-2004, 06:11 PM
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iliketobreakthings
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Default RE: crystal question

thanks for help tigger
Old 06-14-2004, 09:44 PM
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iliketobreakthings
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Default RE: crystal question

so i need a crystal with a frequency from 27.045 to 27.255?
Old 06-14-2004, 11:43 PM
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nownnew
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Default RE: crystal question

I had almost the same experience. The reason those 75mhz crystals don't work in your AM radio is because your radio is not 75mhz AM. Mine is, and if I plug in 27mhz AM crystals, it wouldn't work, even though the new crystals are still AM. So, either buy another set of 27mhz AM crystals or buy a 75mhz AM transmitter, receiver, and crystal. I think the first choice would be easier. Hahaha.
Old 06-15-2004, 02:00 AM
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Tigger N. Bennie
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Default RE: crystal question

ORIGINAL: iliketobreakthings
so i need a crystal with a frequency from 27.045 to 27.255?
It appears as though you need a set of crystals--one for the transmitter and one for the receiver. Most people around here just mention the channel numbers, i.e. 1, 2, 3, 4, 5, or 6. Some crystal sets are also numbered differently. For example some of the Kyosho crystal numbers are red and some are black. Some may have "12" but are actually "6" or some may have "06" and actually be a "3". I don't want to confuse you (some are just "Japanese" numbered and colored), but double check the frequency numbers on both the transmitter crystal and the receiver crystal. Also assuming that both your radio and receiver are one brand, try to purchase that same brand. Myself, I have used Futaba, Kyosho, Losi, Duratrax, JR and so on brands all with my Futaba. However, I have raced where the crystals were regulated to a certain brand and even issued at the race.

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