Frequency Help

[Bandit13]

Will a receiver with a frequency of 62(75.430), work with a transmitter of 82(75.830)? If not; how close do I have to get to the radio to get the receiver to work?

[tamiya]

RX Xtal is 455kHz lower than TX.

[Bandit13]

RX Xtal is 455kHz lower than TX.

Aaaah... Ok???

Now in English!

[Coelacanth]

No. Frequencies of the receiver & transmitter should match. Not sure why tamiya didn't just say so.

[Incredible_Serious]

RX Xtal is 455kHz lower than TX.

No. Frequencies of the receiver & transmitter should match. Not sure why tamiya didn't just say so.

You're both sort of right, depending on the manufacturer. Some will mark their crystals with the same value TX and RX (ie. 27.255 TX and 27.255 RX), whereas some manufacturers mark their crystals with the 455KHz offset (ie. 27.255 TX and 27.710 RX). Tamiya has mixed up the offset, though, as the RX crystal is 455KHz HIGHER than the TX value.

Long story short, for a ch62 / 75.430MHz receiver crystal, you require a 75.430MHz transmitter crystal.

Hope that helps....

Alex

[Bandit13]

Ok. So I can't use a Futaba 82 75.830 radio, with a Futaba 62 75.430 receiver. Even if I use the 82 75.830 RX crystal in the 62 receiver. Is that the consincouse?

[Incredible_Serious]

Ok. So I can't use a Futaba 82 75.830 radio, with a Futaba 62 75.430 receiver. Even if I use the 82 75.830 RX crystal in the 62 receiver. Is that the consincouse?

If you can change the crystals in the transmitter and / or receiver so that the same frequency is in both (ie. 75.830 TX crystal in transmitter, 75.830 RX crystal in receiver), then you should be good to go.

Not sure what a "consincouse" is, though...

Alex

[Bandit13]

Ok. I'll give it a try and let you know.

Consensus - Sorry, typo.

[Coelacanth]

What I said. Unless you want to have issues or it not work at all, receiver & transmitter crystals should have matching frequencies. Often, old radios could use a range of frequencies, but they still needed to match.

[MOmo]

As long as you are using the same Xtal Mfg with the same equipment is also key.

Futaba Xtal and Fut Radio and Receiver.

The Freq. #s do have to match one another in order to communicate, but the Freq. that is printed on the receiver and the Radio don't.

Meaning IF your Receiver came with Freq. 75.830 (Ch 82) and let's say you have a radio that came with 75.530 (ch 67) With each device armed with its respective Xtal, obviously they wont talk. But, as long as you have a TX and RX Xtal of the same freq, regardless of what came in the receiver or the radio, it should work w/o issue as long as its the same make and correct Freq.

I personally have several FM 75mhz xtals and receivers.
To keep it simple, I chose to use Ch 71 (75.610), that way, I would only have to change model #s in my radio (before the 2.4ghz, but computer radio w/ mult model memory)
I have Mult. sets of the receiver Xtal Ch 71 and only 1 Transmitter . Only one of the 6 FM receivers I have match that (75.610 Freq).
I've had 0 issues with any of the receivers and my radio, even though it shows the Freq, 75.830 (Ch 82).

Here is the Futaba Freq. chart.
http://www.futaba-rc.com/faq/frequency.html



MOmo

[jwscab]

ideally, you have the transmitter and receiver that have been tuned at the crystal that they were shipped with. If it was channel 82, you would use the channel 82 xtals, regardless of what the actual tuned frequency is.

NOW, you could mix and match transmitters and receivers(in the same manufacturer) as long as you kept the crystal pairs together. I will say that the further you get from the box stock frequency, you could run into range problems because of tuning variation. This would also apply for old radios that may drift out of adjustment due to aging of the components.

ideally, the manufacturer tunes the rx and tx and then you can swap in any matching crystal pairs, but due to trim tolerances it's not always perfect.