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Old 01-14-2007, 11:07 PM   #1
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Default Crystal Questions

Went looking for Crystals, and saw there are 27mhz AM, and 27mhz FM, for example. They have the same number choices.

1. Can a 27.045 AM run at the same time as a 27.045 FM?

2. Will XMOD Crystals work? (may have already ask this before, sorry)

3. Are there only 6 Channels per Frequency, (ie, 26.995, 27.045, 27.095, 27.145, 27.195, and 27.255) or are there more?

4. 75.570, 75.790, 75.810, 75.950.....Whats missing?

5. Are the TXs/RXs AM, FM specific?

Last edited by oMONSTERo; 01-14-2007 at 11:29 PM. Reason: add
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Old 01-16-2007, 03:38 AM   #2
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anyone willing to help?
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Old 01-16-2007, 08:50 AM   #3
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Quote:
Originally Posted by oMONSTERo
Went looking for Crystals, and saw there are 27mhz AM, and 27mhz FM, for example. They have the same number choices.

1. Can a 27.045 AM run at the same time as a 27.045 FM?

2. Will XMOD Crystals work? (may have already ask this before, sorry)

3. Are there only 6 Channels per Frequency, (ie, 26.995, 27.045, 27.095, 27.145, 27.195, and 27.255) or are there more?

4. 75.570, 75.790, 75.810, 75.950.....Whats missing?

5. Are the TXs/RXs AM, FM specific?
1. I don't think so. I'm no rocket scientist but I think you'd get interference. AM = amplitude modulation, FM = frequency modulation.

This part is my guess and may or may not be scientifically true hehe: If you graph out a steady FM and AM signal on the same channel the lines would intersect at regular intervals. That would cause interference.

2. Yes, they work but only on 27Mhz AM radios. I can't guarantee it will work on all radios though.

EDIT: I found a chart with the frequencies on it. USA uses the 27Mhz and 75Mhz bands for surface vehicles.
http://www.fatlion.com/sailplanes/freqs.html


3. I'm not sure what you are asking here sorry. 27Mhz is 1-6. Each 27 Mhz has a color associated with it but I don't know them. I don't know the frequency values for each number.

4 Again I'm not sure what you are asking here. 75Mhz is channel 61 - 90. I don't know the frequency values for each number.

5. Yes they are specific. You cannot mix an AM transmitter with a FM receiver and vice versa.

Last edited by Rysuleod; 01-16-2007 at 09:28 AM.
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Old 01-16-2007, 08:55 AM   #4
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27mhz there are only 6 channels AM and FM

75mhz there are 30 channels 61-90 AM and FM

No you can't match an AM rx crystal with a FM reciever or the other way around.
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Old 01-16-2007, 09:44 AM   #5
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1. Can a 27.045 AM run at the same time as a 27.045 FM?

No


2. Will XMOD Crystals work? (may have already ask this before, sorry)

Yes, they will work fine in a 27MHz AM radio

3. Are there only 6 Channels per Frequency, (ie, 26.995, 27.045, 27.095, 27.145, 27.195, and 27.255) or are there more?

On 27MHz, there are only 6 allowed in the US. Japan has 12.
FYI: You can can get all 12 ch. of the XMod X'tals at the Shack



4. 75.570, 75.790, 75.810, 75.950.....Whats missing?

???????

5. Are the TXs/RXs AM, FM specific?

Yes
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Old 01-16-2007, 01:46 PM   #6
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ok some of the guys have answered and they were right. but there are a few radios that are gender specfic for their 75 crystals. like airtronics. but in 27 i haven't found any that are gender specfic. but they do have to be the same number/or color since that what most tracks go by/ and they do both have to be am or fm if your radio is 27fm. yes there is only siw freq's in 27 in the usa. yes there are 30 in 75fm from channel 61 to 90. then there is the synthesized like from novak or airtronics that eliminates the crystals. those you can turn some dials on both the radio module and the receiver to tune to any of the 30 channels in 75 band. way kool very helpful at a big race to have. then there is the new spektrum 2.4ghz technology. no crystals and 90 channels for r/c and now way ever that you could be glitched or could get glitched. since that set-up is encrypted codes and when you turn yours on the system finds an open channel in one of the 90 and locks you in. if for some reason a 91st or 92nd or 93rd person was to turn their radios will not lock in and go into a passive mode until a channel opens up.

its a bit confusining at first but i hope this helps. also with the 27 band am and fm can glitch each other usually the fm takes over both cars or whatever your running. as well as most of the vehicles from radio shack, wal-mart and the likes are usually 27 band and can glitch someone as well. so if you see a kid at your track playing with one in the pits it will glitch someone racingthat is on 27. but there are a few that are 49mhz but now many from those places.
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Old 01-16-2007, 03:15 PM   #7
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Default Ok

WOW!! Now thats INFORMATION. Thanks eveyone, including pearldiver for upping the thread at just the right time looks like. I had the post up for hours, then he ask/upped it and BAM!! An avalanche of info. The Chart took care of #s 4 and 5, easily. The XMOD info opens up some possibilities. We got started in RC with XMODS. I love em, and we have ALL the available Crystals + extras.

Thanks again to ALL who responded. Helped TREMENDOUSLY!!!!
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Old 01-16-2007, 07:18 PM   #8
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no worries mate... at least these answers educate some of us RCers!
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Old 02-04-2007, 10:31 PM   #9
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Default Hey

Sorry to bring this up again, but I found our XMOD "upgrade" crystals, and they prompted these questions. If ALL the XMOD Crystals will work, incuding the "odd" ones (ie. 27.025, 27.125, etc), why arent they listed as "available US 27mhz" in the list posted previously?

Thanks
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Old 02-05-2007, 03:26 AM   #10
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its kinda hard to say. as long as you are buying crystals that work with your radio system as long as the tx and rx are the same exact numbers they will work. but like i said once before(well before my other screen name got hijacked) some radios will only work with their crystal and alot will work with anyones crystals. from when i had a 27 band am, any 27 band am crystals worked in it. the only exception was my futaba crystals that are about 22 years old now they didn't work. guess technology changed since then. but like in my m8 when i ran crystals the only ones that worked in airtronics was airtronics crystals. but novak had a synthesized system that worked in sanwa. sanwa is the maker of airtonics systems. but i went to spk about 1 and 1/2 ago and now i have an m11, with spektrum. there are very few people still using crystals at all in racing. im not really sure what info your looking for still. best thing is go to a track hobby shop bring your radio gear and say i need crystals that work for it and get what you need.
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