flyzone13

I am looking for some answers to what should be simple questions, can you have a low band reciever switched to accept high band signals? Iam looking at buying an 8 channel radio that is running on high band everything I have now is low band can I simply switch xtals or do I just get new recievers. I am new to the computer radios and a little confused about the different models can those radios do both airplane and heli or just certain models I dont want to buy a radio that I cant use

Dr1Driver

THEORETICALLY, you can switch from one frequency to any other within the same band, in this case, 72 mHz. Narrow band and dual conversion allow this. Practically, I question it. It's always been my practice, if changing more than 4-5 channels away from the original, to send the radio off and have it re-tuned. I have a trainer I'm building now, for sale, that I'm changing frequencies from 42-TX/59-RX to 50. I'll let y'all know how it goes.

Dr.1

GalenB

My Feedback: (18)

You must be using Futaba equipment as they are the only manufacturer that splits their receivers into high and and low band. Low band is up to channel 35 and high band is channel 36 and higher. From your post it appears that you have existing low band Futaba receivers and have located a high band computer radio transmitter. Is this the case? If it is and the radio has an RF module then all you need do is purchase a new module on your old low band channel. Futaba RF modules are about $50 for a single channel and $90 for a synth module, more for a 9Z synth module. If you want to use your old low band Futaba recievers on the the new high band channel then you should send them in for re-tuning to high band. If your receivers are not Futaba then you'll only need new crystals. At no time should you ever change the crystal in your transmitter as it is illegal. You can change the module as often as you like since it's a complete RF component with its crystal onboard.

Dr1Driver

Question: If changing crystals in a Tx is illegal (and I know it is), why can I buy a set of Rx AND Tx crystals in my LHS? Just wondering...

Dr.1

Scar

My Feedback: (3)

Again? Must you hijack the thread? For what purpose?

Flyzone, if you already have this new 8 channel radio, why not get a module for it, that will operate your existing receiver on the same channel? That's what Galenb was suggesting, and it's a good idea.

Good luck,
Dave Olson

BarracudaHockey

My Feedback: (11)

Dr1 because there are people that are qualified to make the change and have the equipment to test the transmitter output to ensure its within specs.

Your speedometer on your car goes to 120, does that mean its legal to do so?

edited for spelling

dirtybird

My Feedback: (5)

I was told* there is nothing in the Futaba receivers that can be retuned. A low band is a low band and a high band is a high band. You could change a low band to a high band by changing components but it probably would be cheaper just to buy a new receiver. I was also told* that you could change a low band to a high band or visa versa by just changing the crystal. I tried it by changing a channel 50 to channel 23 and then range checking. It worked just fine, I went ahead and flew - no problems. If you try this I recommend you carefully range check it.
* By the LHS and radio repair station.

rctrax

It is my opinion that the hi band-lo band question is of no consequence as it merly means that the factory simply tunned each rx to either the area between 35 and 60 for hi band and tunned it for the centerof the area between 11 and 35 for lo band. these diffences are signifcant at the extreme range that these radios will operate at which is far beyond what we normally operate. You can only control it as far as you can see it. At our normal operating ranges we would not even be able to see the difference. It is just a matter of how far the rx will recieve a clear signal, the way it's tunned. There are poeple that say you needn't be too concerned about the antenna length as long as it is close to the orginal length. It is all contribiting to the total range it can be expected to operate at. I use all my rx's without regard to lo band or hi band and I see no difference.If the other manufacturers can do it there is no reason futuba cannot be used the same way. It is just their way of making their equipment a little better than the ones that don't
do this.
This is just my opinion as I am not an expert and juist saying this for what it's worth

Zeeb

My Feedback: (41)

Well as has been mentioned, this question is probably in regard to the Futaba equipment. IMHO, buying the appropriate tx module for your existing rx channel would be the best option as Futaba says that changing to either high or low requires that the rx be sent in to the service center.

As noted above, that would probably be more money than the new tx module plus down time for you, unless you've only got a couple of rx's in which case it might be worth it. I don't know what the difference is, but I run mostly Futaba R149DP rx's and about a year ago Futaba started selling those rx's that will accept either high or low band crystals, up to that point you had to choose one or the other. I can't say about the other rx's Futaba makes as I haven't looked at those...

On the plus side, IIRC the frequency module for the 8 channel radio should work on the newer 9C series should you elect to upgrade later on.

RhyanO

I have a High Band Transmitter CH 40. and a Low Band Reciever 29 (changed to 40) with no re-tuning. Works just fine. I did a range check and found no glitches.... I have flown this reciever for 2 years with no problems.
Id think that if a standard range check is okay, then it is good to fly.

Ryan

piper_chuck

My Feedback: (12)

Relying on a range check to disprove a manufacturer's recommendation is risky. Sure, it worked ok on a range check. What about when there are 5 people on the flight line operating on channels near yours and your plane is the furthest away? How well does that less than optimally tuned receiver work when it's subject to more interferance than normal? Perhaps it will be ok, but is it worth risking your plane for the $20 it would cost to send the receiver in for retuing?

RhyanO

Good point Chuck.
Do you know the charge to re-tune a reciever? Just courious.
Just wondering if it is cheaper to just buy a new one, than send one in to be re-tuned.

Thanks,
Ryan

vertigo72480

As a ham radio operator, I can tell you that no, it is not illegal to change the frequency. It is unlawful for the original manufacturer to sell the product without the original frequency specified as it must pass FCC regulations. Most radios and receivers are tuned to the center of the frequency envelope. The high band and low band of Futaba still baffles me, but I believe that it is simply a deviation in tuning. I have changed the transmission and receiving frequencies of a few transmitters and receivers and then taken them to another ham buddies shack to test their deviation. As with most crystal controlled transmitters, the frequency was dead on, and the radios had no loss in output power. Not everybody has the opportunity to do this, but that's the advantage of being a radio geek. Bottom line, just do a full range check before you toss anything into the air.

piper_chuck

My Feedback: (12)

I haven't checked the prices lately, but it was surprisingly low. You could try sending an email to Radio South: http://www.radiosouthrc.com/

piper_chuck

My Feedback: (12)

I agree it's not illegal to change the frequency of a receiver...