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Author Topic: Radio problems  (Read 3036 times)

Ian Robins

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Radio problems
« on: August 20, 2007, 10:02:55 pm »

Hi all,
Just a few notes on the problems I had with one of our members boats.
The boat is a IMARA tug (single screw) with two channel radio, one Hitech 610 speed controller, a blower motor and two 12v 7a batteries.
The first problem was on the bank ampage was 1.5 amps in the water 15 amps.
First thing gear the motor 4:1 with a home made gearbox (ampage now down to realist level), speed control now a viper 15amp
Tried the model, power ok but no radio range
Got home and checked the radio, transmitter 40mhz am, 40mhz crystals, 27mhz am reciever. range 6 ft (didnt believe it could work like this)
tried my 27mhz transmitter and crystals no problem

The transmitter is a futaba but no frequency is written on the case.
Anyway in future If I fix (or attempt to) I will check

Transmitter frequency
Crystals
reciever frequency

has anyone else had these problems

ro88o
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GG

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Re: Radio problems
« Reply #1 on: August 20, 2007, 10:59:54 pm »

Two questions;
1) have you tried the radio out of the model?
2) where is the aerial on the model?
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Peterm

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Re: Radio problems
« Reply #2 on: August 21, 2007, 08:23:57 am »

Just a couple of additional points:   Are the crystals of the same manufacture as the RC system?   Is the receiver single or dual conversion, and have you got the correct type of receiver crystal?   You said a 27MHz receiver, I presume that was a typo error.   Pete M
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I`m not just old, I`m ancient

Stavros

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Re: Radio problems
« Reply #3 on: August 21, 2007, 09:21:56 am »

If the crystals are FM and you are using them in a AM set well thats your problem just had it on a Futabs F16 obviously teh same thing will happen if the AM and FM are the other way around and also if one crystal is FM and the other AM. Were teh crystals teh wrong way around ie transmitter in the reciever or vice versa.


Stavros
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DickyD

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Re: Radio problems
« Reply #4 on: August 21, 2007, 09:38:41 am »

If you are using a 40mhz Tx and a 27mhz Rx this is not going to work.
You need a 40mhz AM Tx and Rx with 40 mhz crystals [Tx in Tx and Rx in Rx]
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Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

Telstar

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Re: Radio problems
« Reply #5 on: August 21, 2007, 11:48:53 am »

Hi ro88o
transmitter 40MHz am, 40MHz crystals, 27MHz am receiver?  You have already spotted your radio problem.
Al tho a 27MHz AM Rx will work on 40MHz AM (if fitted with the correct 40MHz Xtal) the sensitivity hence range will be total rubbish (6ft mentioned is good). AM single conversion Rx's normally use the same IF (intermediate frequency) so if you throw a strong enough RF (Radio Frequency) at it to overpower the RF tuning the Rx will respond.
Replacing the 27MHz Rx with the correct 40MHz one  should solve the range problem

Cheers Tom
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DickyD

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Re: Radio problems
« Reply #6 on: August 21, 2007, 12:12:01 pm »

Thats what I said  O0
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Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

Telstar

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Re: Radio problems
« Reply #7 on: August 21, 2007, 12:23:50 pm »


Thats what I said  O0
So it is Richard   I was just trying to point out that although the wrong set up may work on the bench it would be no good on the water. Didn't mean to tread on any toes
Cheers Tom
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DickyD

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Re: Radio problems
« Reply #8 on: August 21, 2007, 12:33:27 pm »

No problem  ;)
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Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk
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