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Old radio work?

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Old 02-02-2011, 03:12 PM
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ezrollin
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Default Old radio work?

Ihave an old Tower Hobbies radio chan 60 on frequency 72.990 and also another crystal for 72.190. The system is about 13 yrs old. Is there any way to tell if I'm going to get interference without having first flown it? If so, can Ijust update(change) the crystals and be good to go? thanks
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Old 02-02-2011, 04:43 PM
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Default RE: Old radio work?

OK - I assume this is an FM radio. Anything after 1991 should be good to use with proper Frequency Control at any RC Flying Field. You say you have a Tower Hobbies Transmitter on Ch60 (72.990). You also have a Crystal for Ch20 (72.190). If this is a Transmitter Crystal, you are not Legally supposed to change Transmitter Crystals, yourself, but instead, you should send it in to have the Crystal installed and the Transmitter retuned.

You can change Receiver Crystals, yourself, the Channel number, of the Crystal in the Receiver, must be the same as the Channel Number of the Crystal in the Transmitter.

As far as Interference goes, any AMA Sanctioned Flying Field should have a Frequency Board with spots for all 50 Channels on 72Mhz, for example. You should never turn on your 72Mhz Transmitter unless you have the Frequency Pin for that Channel.

If your Tower Hobbies Transmitter has not been sent in for many years, you should send it in to be checked. If it is out of Tune, it could interfere with other Channels.
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Old 02-02-2011, 04:46 PM
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Default RE: Old radio work?


ezrollin,

It is not legal to change transmitter frequency.
I has to be done by a licensed technician.

FYI ___There would be a xtal also in the receiver that would have to be changed.

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Old 02-03-2011, 04:59 PM
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ezrollin
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Default RE: Old radio work?

I hadnt thought about the transmitter vs crystals

In my Tower Hobbies Tx and RX its on 72.990
I had a 20 yr old Futaba 4 chan which Ijust threw away cause Iknow for sure its gonna get interference.
I have another 8ch computerized Futaba Tx on 72.190 which Ithink I'm just gonna give away to the first person I see.

The reason Iwas asking this question was because I turned on my Tower Hobbies Rx and my servos seemed to twitch every once in awhile. Iwas wondering if Iwas getting interference or something and was scared about setting up this plane with a bad radio system = crash and burn. (Regardless I'm gonna end up crashing it anyways haha)

2.4GHz > 72 FM?
thanks!
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Old 02-03-2011, 06:49 PM
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Default RE: Old radio work?

ezrollin - I have used 72Mhz for 33 years. Turning on the Tx and having servos Twitch is not necessarily a sign that the radio is experiencing Interference. It could be that your Tx was too close to the Rx and you were Swamping it. It could be that the Voltage of the battery in the Tx or Rx was too low. Your Tx and/or Rx may need to be ReTuned. Depending upon the age of your Servos, they may have dirty Pots. Your Rx could have a damaged antenna.

You really need to do a Range Check, outside.

I love 2.4 radios and prefer them over 72Mhz. There have been so many features added to RC radios in the past 13 years, but your radio is not necessarily Junk.
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Old 02-04-2011, 06:55 AM
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Default RE: Old radio work?

ORIGINAL: ezrollin

The reason I was asking this question was because I turned on my Tower Hobbies Rx and my servos seemed to twitch every once in awhile. I was wondering if I was getting interference or something and was scared about setting up this plane with a bad radio system = crash and burn.
Do you know how to perform a range test? That simple test has worked for the age of the 72Mhz band and problems have been found while doing this simple test and models have been saved.

I'm going to assume that you do not know what a range test is. So here we go.
1. Leave the antenna of your radio collapsed inside the radio.
2. Turn on the radio and the receiver.
3. Place the aircraft away from metal objects like a tin roof, or vehicles. Preferably at waist level but ground level should be sufficient if the field is open.
4. While moving the sticks on the transmitter, Start walking away from the model counting your steps. Stop when the model does not react to the commands of the transmitter.
5. Walk back, substracting the steps from the original count until you re-gain control of the model.

I typically get about 80 paces before I start loosing control. Find the absolute minimum distance from the manual of your radio.

Servos twitching in an enclosed area, or under a metal roof do not mean anything. Since you do not describe the location of your test, I'm going to assume that you did the test indoors.

2.4GHz > 72 FM?
What is the purpose of this comment / statement / writing?

Rafael
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