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Narrow banding Question

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Old 01-25-2010, 04:49 PM
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gene6029
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Default Narrow banding Question


I recently bought a Cannon 2 channel radio on 72.320mhz. Who can narrow band this radio for me, so i can use it in my vintage models? I have the reciever and servos all working on the above frequency. Thanks.....Gene[]
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Old 01-25-2010, 04:51 PM
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iflyj3
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Default RE: Narrow banding Question


ORIGINAL: gene6029


I recently bought a Cannon 2 channel radio on 72.320mhz. Who can narrow band this radio for me, so i can use it in my vintage models? I have the reciever and servos all working on the above frequency. Thanks.....Gene[]
Contact Tony Stillman at Radio South at http://www.radiosouthrc.com/
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Old 01-25-2010, 04:56 PM
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Default RE: Narrow banding Question

Tony does all my Kraft radios & Futabas, but doesnt have the info to do the Cannons......Gene[]
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Old 01-25-2010, 05:00 PM
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Default RE: Narrow banding Question


ORIGINAL: gene6029

Tony does all my Kraft radios & Futabas, but doesnt have the info to do the Cannons......Gene[]
I don't know if Cannon was ever narrow banded or not. The only other two possibilities I know of are Kraft Midwest (Pete Waters) or Jay Mendosa (Jaymen on RCU). If they can't do it, it is possible it can't be done.
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Old 01-25-2010, 08:52 PM
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Default RE: Narrow banding Question

Or, perhaps Tony has gotten the info recently. An email will tell you. If he can't do it, he could tell you who could.

FYI, there are now two Radio South locations. Ben Pham is still working out of the one in Pensacola. I think that Tony moved to Georgia and is working out of there as a second location.

Just my $.02

Bob
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Old 01-26-2010, 05:58 AM
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Default RE: Narrow banding Question

I contacted Tony first, since he regularly has one of my radios from my collection in his shop being narrow banded. He informed me he could not do it & didnt mention anyone who could. If i understand it correctly, the reciever is the culprit i believe. At this point i dont mind if i have to use a newer reciever, just to be able to use the transmitter......Gene
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Old 01-26-2010, 12:54 PM
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Default RE: Narrow banding Question

Modifying R/C AM transmitters to meet the 1991 AMA narrow band specifications.

The main reason most R/C transmitters do not meet the narrow band requirements has to do with way the carrier is amplitude modulated (AM) and the tuning of the output and antenna networks. Ace added a Miller integrator circuit to properly shape and roll off the sharp corners of the modulation pulses on the Silver Seven and Micro-Pro series transmitters, making their 72MHz RF deck narrow band and Gold Sticker compliant.

Unfortunately, earlier radios did not use a seperate RF deck; the RF section was usually built on the same circuit board with everything else. In this case, it is possible to add the required circuitry, but depending on the layout and size of the circuit board, it may be extremely difficult, or time consuming. For that reason, many of the older transmitters of this type have to be modified; the RF section is disconnected and a new Gold Sticker module is wired in. The modulation pulse train and shaping circuit will often require modification, or the addition of the afore mentioned Miller integrator added to make the transmitter narrow band. It is also possible to convert the transmitter to FM by adding an FM narrow band module, and required circuitry needed to adapt it to the existing encoder circuitry.

As far as receivers go, the only practical option is to replace them with a newer narrow band dual conversion type, as it is impractical to add the circuitry to a wide band receiver to update it.

It must also be noted here that the transmitter then has to be certified as narrow band by doing a bandwidth check of fundemental frequency, and the amplitude of it's harmonics to assure they are within specifications. This requires the use of some very expensive test equipment, namely a spectrum analyzer, and/or a service minotor, either of which cost well over $5000.00. Most shops do not have this type of equipment, and therefore it is hard to find someone who can do the modifications for a reasonable fee. Most Ham and Amature radio operators will usually have the resources to do this type of work, if you can find one who is willing to do it!
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Old 01-26-2010, 05:30 PM
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Default RE: Narrow banding Question

Jaymen, thank you for that explaination. Looks like i probably wont be getting my cannon radio narrowbanded. I guess my other option would be to gut the radio & replace the electronics with those from a donar radio. I've seen it done before and with this being only a 2 channel radio that may be the road i travel down. Thanks again for all the input that has been given...Gene
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Old 01-26-2010, 07:38 PM
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Default RE: Narrow banding Question

Let me toss something out for discussion... how about if (with your Club's permission) you only flew the airplane when you were the only person at the field, or if/when everyone agreed to stand down to let you fly. This could be similar to an 'exception' for historical reasons. For example, a vintage engine doesn't have to fly with a muffler (does it??). This would be in a similar vein, wouldn't it? This plane could be used as a demonstration to show other RC enthusiasts how things 'used to be in the old days'.

It'd be a shame to gut the radio. Just my $.02

Bob
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Old 01-26-2010, 07:43 PM
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Default RE: Narrow banding Question

ORIGINAL: N1EDM

Let me toss something out for discussion... how about if (with your Club's permission) you only flew the airplane when you were the only person at the field, or if/when everyone agreed to stand down to let you fly. This could be similar to an 'exception' for historical reasons. For example, a vintage engine doesn't have to fly with a muffler (does it??). This would be in a similar vein, wouldn't it? This plane could be used as a demonstration to show other RC enthusiasts how things 'used to be in the old days'.

It'd be a shame to gut the radio. Just my $.02

Bob
No it is not the same as a muffler rule. The FCC is envolved and it is an illegal transmitter because of frequency and band width. The club can not negate the law.
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Old 01-30-2010, 01:29 AM
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Default RE: Narrow banding Question

Dan is right. 72.320 is no longer a legal frequency. That was one of the original 72 mHz frequencies the FCC first granted us for use in R/C in 1966. Only AM transmission was permitted under those rules. The 50 new 72 mHz frequencies that we use now, on which FM is legal, became available in 1991. At that point, the old ones became illegal.

In their day, Cannon made good radios and the company worked hard to reduce sizes and weights of the airborne components to make smaller models more practical. But the R/C world has changed greatly since the 70's and 80's and today's equipment is enormously more advanced than the best of that era and on top of that, today's electronics is also much less expensive than the stuff of a few decades ago so it's hard to justify the expense of putting old radios like that back into service.
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