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Futaba RX's and Hitec Crystals

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Old 07-23-2007, 08:58 PM
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deckerv
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Default Futaba RX's and Hitec Crystals

Hello...just wondering if they're compatible. I have about 7 Hitec crystals all on Ch 40, but few Futaba crystals. All are dual conversion as well as all of my Futaba/Hitec receivers. Any thoughts...am I playing with fire if I were to use a hitec crystal in a Futaba rx?
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Old 07-23-2007, 10:18 PM
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Default RE: Futaba RX's and Hitec Crystals

Futaba says so.
Try this: setup a plane with the Futaba RX / Hitec crystal and give it a FULL range check. That means your buddy holds and watches the plane while you, continuously moving the sticks in a rhythmic pattern, walk off at least 1000 feet! Better yet, walk off until the RX does start to glitch so you will know the exact range of your setup. If you can do the test with the motor running, so much the better. Your buddy is to signal you the instant he sees a glitch.
If it all checks out, you're good. If it doesn't, at least you didn't lose the plane in a crash.

On the other hand, crystals are cheap - is it really worth the $14 you might save?
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Old 07-23-2007, 10:46 PM
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Dave McDonald
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Default RE: Futaba RX's and Hitec Crystals

Despite the official lines by Futaba and Hitec, I've been flying Hitec crystals in Futaba receivers for years without a single problem.

Do an antenna collapsed range check with a Futaba crystal, then do a range check with the Hitec crystal. If the Hitec is the same or better, you're good to go.
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Old 07-25-2007, 05:16 AM
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Default RE: Futaba RX's and Hitec Crystals


ORIGINAL: Dave McDonald Despite the official lines by Futaba and Hitec, I've been flying Hitec crystals in Futaba receivers for years without a single problem. Do an antenna collapsed range check with a Futaba crystal, then do a range check with the Hitec crystal. If the Hitec is the same or better, you're good to go.
Crystals are no longer interchangeable between brands. Whilst you may get reasonable results in good conditions with Hitec xtals in Futaba RX, Hitec crystals must be used in Hitec RX for optimum results. Futaba single conversion RX crystals may appear to work but with proven less range and glitching, especially noticeable in damp weather or wet ground. Local radio technician was surprised but ran a number of tests with result he is also now convinced that there is a significant difference in the crystals. See RC Groups Sticky - Data - What type of crystal do you need ? also the crystal comparison chart from GWS and more under both "Crystals, Oscilators & Piezo " and "Receiver - FAQ, guides and aids to best reception.." on my web page.
Transmitter Crystals - do not interchange between brands except as listed by GWS
Crystal Compatability Chart for RC units (courtesy GWS)
The following may also assist:
Single Conversion vs Dual Conversion - fact sheet
IPD (Intelligent Pulse Decoding) Receivers - FAQ .pdf file
and RC Groups "Sticky"
What type of crystal do you need ?
see also sub section "Crystals, Oscillators & Piezo " under "Radio Systems, Accessories, Alterations and FAQ" on my web page.
Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links[/


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Old 07-25-2007, 12:56 PM
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Default RE: Futaba RX's and Hitec Crystals

While it's true that a single conversion crystal can't replace a dual conversion cyrstal, the original post clearly stated he was dealing with dual conversion receivers and crystals.

I have about 7 Hitec crystals all on Ch 40, but few Futaba crystals. All are dual conversion as well as all of my Futaba/Hitec receivers.
Since the original post dealt only with Futaba and Hitec dual conversion crystals, my answer was based on my experience with Futaba and Hitec dual conversion crystals. For me they have proven to be completely interchangable.
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Old 07-25-2007, 04:30 PM
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Default RE: Futaba RX's and Hitec Crystals


ORIGINAL: Dave McDonald While it's true that a single conversion crystal can't replace a dual conversion cyrstal, the original post clearly stated he was dealing with dual conversion receivers and crystals.
I have about 7 Hitec crystals all on Ch 40, but few Futaba crystals. All are dual conversion as well as all of my Futaba/Hitec receivers.
Since the original post dealt only with Futaba and Hitec dual conversion crystals, my answer was based on my experience with Futaba and Hitec dual conversion crystals. For me they have proven to be completely interchangable.
Whilst some USA residents have reported Futaba and Hitec DC RX Xtals have been interchanged on 72 MHz, for clarification of those who did not notice originators query related to USA Ch40 (72.590), 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 a local xtal manufacturer, who supplies USA military, has confirmed the specifications between the two brands are different. There is also a difference in physical sizes, Futaba RX crystals are slightly larger and do not fit correctly into Hitec RX with either the correct vibration damping rubber boot or bands, as applicable and provided with each Hitec RX, in place. Futaba TX xtals do not fit into Hitec TX Xtal holders.
If you are quite relaxed about risking an expensive model, and possibly hours of work, against a few pennies worth of the correct crystal for optimum performance, so be it.
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Old 07-26-2007, 11:55 PM
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Default RE: Futaba RX's and Hitec Crystals


ORIGINAL: deckerv

Hello...just wondering if they're compatible. I have about 7 Hitec crystals all on Ch 40, but few Futaba crystals. All are dual conversion as well as all of my Futaba/Hitec receivers. Any thoughts...
Here's one. Buy some HITEC receivers to use with those Hitec crystals.

Another thought is to be skeptical of claims that if it passes a range check, it must be ok. While such casual testing might be ok for a specific person at a specific field, or fields, such imprecise methods do little to ensure safe operation. If you really want to confirm it's ok, send a receiver and the crystals to someone who can measure the performance of the Futaba receiver with a Hitec crystal compared to what they get with a Futaba crystal. If the results are the same, you're good to go. If not, you've saved a plane...
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Old 07-27-2007, 10:47 AM
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Default RE: Futaba RX's and Hitec Crystals

I wish I had the bench stuff available now that I had when I was an avionics tech in the Navy. I'd drag out a signal generator and an o-scope and make some videos.
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Old 07-30-2007, 12:20 PM
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Default RE: Futaba RX's and Hitec Crystals

Anyone who has ever seen Dave McDonald fly can attest to the fact that he is probally 1 of the top 10 pilots on this site, If he says hitec crystal are ok in futaba thats good enough for me.
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