Question about crystals

As far as I know, you must use the same christal as in the the transmitter. If you have a Futaba transmitter, your receiver must be equipped with a Futaba receiver christal with the same channel.

Regards. Fil

"Mike R." schreef in bericht news: snipped-for-privacy@posting.google.com...

Please refer to the numerous previous posts.

Note = From: Hitecrcd ( snipped-for-privacy@aol.com) Subject: Re: Hitec receiver crystal for Futaba receiver Newsgroups: rec.models.rc.air View this article only Date: 1996/04/03 Contrary to popular belief I do not recommend using a Hitec crystal. They are totally different in cut, overtone value and a few other specs. You cannot buy Hitec TX crystals. FCC regulations requires transmitters to be tuned to specifications and does not allow for the user to change the TX frequency. Bryan Shaw GM Hitec RCD, Inc.

USA residents report that Xtals on 72 MHz have been interchanged. However, Xtals on 35, 36 & 40 MHz are not interchangeable as per statement above and our own tests in this country.. Hitec DC RX crystals on 35.36 & 40MHz have a frequency 10.7MHz ABOVE the nominal frequency whereas Futaba DC RX crystals are 10.7MHz BELOW nominal frequency. Hitec FM TX xtals are cut at half nominal frequency whereas the Futaba FM TX xtals are cut at 1/3 nominal frequency. see further details under the URL's at Alan's Hobby Web Links

FWIW the Local xtal manufacturer who supplies major international buyers inc USA, can copy Futaba xtals but has an 80% failure rate trying to copy Hitec xtals and now refuses to try as they advise the Hitec specs are to far advanced for any other but the current manufacturer to achieve. i.e. Use the band of xtal relevant to the unit it is being inserted into = Futaba TX use Futaba TX xtal, Hitec RX use a Hitec RX xtal.

regards Alan T.

transmitter.

Ah you speak of that which you don't know. The reciever must match the transmitters FREQUENCY not the make of the crystal. It also must match the positive or negative shift of the Transmitter. I use several different recievers with my Futaba radio and they don't have Futaba crystals in them. If they tell you to use a Futaba crystal, I would think you should use one. Eddie Fulmer AMA 63713

You need the same brand xtal in the transmitter as the transmitter

You need the same brand xtal in the receiver as the reciever (maker recommeends).

Both have to be on the same channel.

Dual conversion receiver crystals won't work in single conversions receivers and vice versa.

No. I've used Hitec and aftermarket crystals in Futaba and FMS RXs and Futaba TXs many times. You only need to be sure to get the same phase-shift crystal to match your TX and RX. Dr.1 Driver "There's a Hun in the sun!"

Was it a single conversion crystal???????

I DO know that GWS single conversion crystal will work fine - that's what I'm using in my GP rx/esc right now.

David

I have used Hitec in Futaba also. The key on the Electrifly is that it's a single conversion receiver so it will need a single conversion crystal.

Gerald,

Again, the High Low issue relates only to recent Futaba 72 MHz RX. There is no such thing as positive or negative shift on any other frequency except 72 MHz.

Xtals on 35, 36 & 40 MHz are not interchangeable.

Hitec DC RX crystals on 35.36 & 40MHz have a frequency 10.7MHz ABOVE the nominal frequency whereas Futaba DC RX crystals are 10.7MHz BELOW nominal frequency. Hitec FM TX xtals are cut at half nominal frequency whereas the Futaba FM TX xtals are cut at 1/3 nominal frequency.

FWIW The circuit diagrams for some popular USA 72 MHz TX are not always the same as those used in other countries - i.e.Some top end 8 & 9 Ch sets on 72 Mhz ex USA, seen in this country, do not have all the features of the same set sold in Europe and Asia, with some boards and LCD screens being quite different parts.

regards Alan T. Alan's Hobby, Model & RC Links

Futaba TXs many times. You only need to be sure to get the same phase-shift crystal

Mmm. Not necessarily. All crystals are rated at a ceertain capacitative loading, and not all equipment presents the same loading.

Tests were done in the UK and showed wrong brand Xtals could result in transmitter or receiver frequencies off by up to 3khz.

Of course your gear will still work....but you are halfway into the next door channel..... vastly increasing cahnces of a shoot down.

Of course, some of us prefer to fly legally :-)

Would you explain what this "same phase-shift crystal" means?

Dan Thompson (AMA 32873, EAA 60974, WB4GUK, GROL) remove POST in address for email

Except 50 and 53 MHz here in the colonies. Rx's are/were available with both shifts.

Dan Thompson (AMA 32873, EAA 60974, WB4GUK, GROL) remove POST in address for email

Phase shift refers to the manufacturer's use. Some make radios and crystals with a positive shift in the signal, some with negative. They will not interchange. Dr.1 Driver "There's a Hun in the sun!"

Its more a fdrequency shoft than a phase shift.

In positive shift the carrier is a little below center frequency and moudulates above to encode the pusles. And reverse in the case of negative shift. This affcets the excat frequencty needed on te TXXtal

The receiver crystal doesn't change frequency as a result tho.

It still needs to be bang on the center of the channel, plus (or minus) the IF frequency.

The receiver itself needs to be designed to cope with the right 'shift' not the crystal.

Works for me. Dr.1 Driver "There's a Hun in the sun!"