Futaba High Band / Low Band
 

How serious an issue is it to put say, a low band channel 21 crystal in a high band channel 36 receiver?

RE: Futaba High Band / Low Band
 

The issue is with reduced range. Receivers are tuned for a specific frequency or band of frequencies and the further from that frequency the crystal, the worse the reception. Think of turning the dial on an analog AM/FM radio; the closer you get to the actual frequency of the radio station, the clearer the signal. Futaba receivers are tuned for the middle of the low or high bands; around channel 22 for low band and channel 47 for high.

If you're flying helicopters, park flyers or other aircraft at close range it won't be much of a problem. The range of a properly tuned radio/receiver system can be more than a mile; well outside the limits of visual recognition. So if you're not too far off frequency, the reduction in range won't be that significant.

FYI: I recently sent a crashed low band with a channel 16 crystal to Futaba for repair. When they repaired it, they tuned it for a much narrower band; specifically for channel 16; and suggested that if I changed crystals, not to go more than +/- 3 channels from 16.

Keith

RE: Futaba High Band / Low Band
 

I am using a channel 21 crystal in a channel 52 receiver and have had no problems. It is in a 1/4 size extra 300 with a saito 150. I don't know if I am just lucky, but I did a good ground check and figured if it worked there it would be good with the antenna out and in the air also. So far, as I said, no problems.

RE: Futaba High Band / Low Band
 

I think Futaba are the only receivers that have a high/low band... I use Airtronics and with theirs as long as you get a good range check after swapping crystals, you're all set.

RE: Futaba High Band / Low Band
 

When Futaba started the whole hi/low band a few years ago I was a bit sceptical. Recently I took different hi/low rx and switched crystals - guess what, no reduction in range. Talking to a few guys (all with a few decades of experience) today at the field, they agreed that Futaba is using some creative marketing to sell more rx's. Range check for yourself and you'll see there is no difference -

RE: Futaba High Band / Low Band
 

Kind of what I expected. Thanks for the replies.

RE: Futaba High Band / Low Band
 

Ron,

How did you check the range when you switched crystals? Do you mean that you did a range check and it was still ok? Or you checked the max range before the switch and the max range afterward and they were the same?

I would agree that a standard range check will probably show that the receiver works fine. But that doesn't mean you didn't loose any range. I've had a couple decades of RC experience myself and haven't seen a reduction of range either. But that's because I never check the maximum range; instead, just do the standard range check like everyone else. Unless you're flying 1/4 mile away from yourself, you will not likely see any difference. It's just not a chance I'm willing to take with $1000+ helicopter when it's not necessary.

Keith

RE: Futaba High Band / Low Band
 

I have never heard of this in the UK. We operate on 35Mhz with 36 channels seperated by 10Khz. That's from 34.950MHz (ch 55)to 35.300MHz (ch 90), and I've never seen any reference to limits applied to any receiver or transmitter. It's common practice here to swap crystals to avoid clashing with another flier. I accept that the aerial tuning circuits will not be (cannot be) absolutely peaked throughout the band and this will result in a slight reduction of range, but it's a change from out of sight, to a long way out of sight. In any case a lot further away than I'd be comfortable flying, and well outside the designated flying limits of my club site.

Which Futaba receivers are these high/low limits applied to?

Geoff

RE: Futaba High Band / Low Band
 

72 Mhz ones.

http://www.futaba-rc.com/radioaccys/futl0511.html

RE: Futaba High Band / Low Band
 

To my knowledge high band starts at ch. 38

RE: Futaba High Band / Low Band
 

Frank,

High band is from 36-60, with low band being 11-35.

Keith

RE: Futaba High Band / Low Band
 

If Futaba gets you to buy an extra RX with a perfectly good one sitting on your shelf, then they have done their job, which is to increase sales. If it is important at all why doesn't JR do it. Futaba correctly assumes that if you have a 1000 into an heli or airplane whats a few more $ to make sure you have that extra bit of insurance. Good marketing.

RE: Futaba High Band / Low Band
 

I'm an electrical engineer with some amateur radio experience as well. Everything said here is right MOST of the time. If all of the components in the receiver are tuned to their optimum values then you'll be fine. However, electronic components are generally specified to be within a certain tolerance of their listed values. Some are at the middle of the range, some at the bottom, and some at the top. If you get enough components that are at the wrong end of the tolerance scale then you may have a reduction in receiver performance that is noticeable between high band and low band.

My guess (and that's all it is) is that the Futaba engineers are trying to make sure that their receivers are ALWAYS in spec even if the components are skewed one way or the other. Since they charge the same price for high/low band receivers and it would only be an issue if you hopped 30 channels, I doubt it's a marketing ploy, just cautious engineering.

Range checks only tell part of the story. Unless you have a way to measure things like signal to noise ratios you won't know how close to failure you really are until it's too late. Either way, it's your plane. :)

RE: Futaba High Band / Low Band
 

I love this site....I had about ten questions and they were all answered here in this thread


where was RCU 10 years ago???

RE: Futaba High Band / Low Band
 

ARE ALL THESE FUTABA Tx 72 MHz?
COULD I BUY ANY 9CAP AND HAVE IT WORK ON MY CURRENT Rx WHICH IS CHANNEL 38?
I'M NEW TO ALL THIS AND WOULD LIKE TO UPGRADE MY Tx

RE: Futaba High Band / Low Band
 

hobbsholepro,

The 9CAP can use any frequency module from any band; 72MHz, 75MHz, 35MHz, etc. You would just need to ask for a channel 38 module when you bought it. This is assuming that your current receiver is a Futaba or Hitec. It will not work with JR or Airtronics.

Keith

RE: Futaba High Band / Low Band
 

What year did Futaba start the high band/low band? I just found a complete Futaba Conquest PCM system brand new in the box. I couldn't pass it up after the guy took my offer for $100. (cheaper than a flight pack alone.)

The paperwork doesn't mention anything about the high/low band, but the radio is on Channel 26. I have always flown Ch 36, so if this system was tuned to the middle of the spectrum, I would like to re-crystal it for 36 so I can fly the PCM on my T6XAs, and have the conquest as a back up transmitter.

Does anyone know if this would be a problem?

Bob