Nexion Data Systems

Unified Communications - Remote Data Solutions

nexion NX6440

What about the continuous transmission limiter built into my radio ?

  • Most VHF/UHF transceivers are configured to limit continuous transmissions to a count of 60 - 90 seconds. This counter is automatically reset to 0 when transmitting stops.
    In many cases a continuous data transmission will periodically receive acknowledgement back from the destination before continuing the transmission. Since this short RX automatically resets the transmission timer counter, overall transmission can easily be nearly 100% - which may cause the transceiver to overheat.

Do I have to use a thermal switch ? Can't I just have a fan on all the time the radio is on ?

  • Improving heat dissipation is an important factor to extending a transceivers duty cycle. If it is positioned correctly and power consumption is no issue, having a fan continuously cooling a transceiver will probably help significantly.

What is Heat Soak ?

  • Heat soak is the effect of residual temperatures moving from a hot source towards a cooler place. Heat soak occurs over time and temperatures measured at one physical location may not accurately reflect the overall temperature of the part.
    Turn your car off when it is hot, taking note of the temperature gauge position. Wait 2 minutes and turn on the ignition. The temperature gauge reads higher now than when the engine was running. The heat accumulated in the metals of the motor has moved into the now disabled cooling system.

I'll just hook up a fan to run when I transmit. That'll do it, won't it ?

  • Not necessarily - residual heat may still be flowing towards the cooling surface of the transmitter after transmission ceases. See 'What is Heat Soak ?'.

I need to run my data application for up to hours at a time. What can I do ?

  • Mobile transceivers are probably not suitable for your application. Base units with 100% rated duty cycles will need to be considered.


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Unit 1, 53 Boyland Avenue,
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