FMA Direct T-80RF transmitter with antenna retracted/collapsed as far as it will go into the case, as it should be during radio-range verification test.
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FMA Direct T-80RF transmitter with antenna retracted/collapsed as far as it will go into the case, as it should be during radio-range verification test. |
Q-32: My RC system instruction book describes a simulated ground range check that you perform with the transmitter antenna fully retracted or at least down to the bottom section. I have had local fliers indicate that operating the transmitter in that manner could damage the internal circuits. What is your advice on this?
A-32: Retracting the transmitter antenna will greatly reduce the power output. This condition provides for a convenient RC-system range-verification test. The manufacturers advise you to operate your receiver (inside the model) and walk away from it holding your transmitter with the collapsed antenna. While you do this, you continuously operate one control surface.
If you can obtain solid control for 50-100 feet, the assumption is that you will have normal radio range when you fully extend the transmitter's antenna. This test is simple to do and takes little time. It also enables you to run the test close in rather than walk a half mile away.
Running a range test such as this with the antenna fully or partially retracted is okay because you are doing it for only a few minutes. But here is where a problem can result. Let's say you don’t have a battery discharger and want to take the battery down to cycle it. In your shop, you turn on the transmitter with the antenna collapsed and walk away, leaving it operating for several hours.
First, you shouldn’t be operating the transmitter "in the blind." Even with the antenna collapsed and the signal reduced, it is still broadcasting a signal. Second, and even more important, with the antenna collapsed, your transmitter output circuit is now out of tune. As such, the output current could go way up and the output stage transistor(s) can easily burn out.
Those are reasons why you should only operate your RC transmitter with the antenna collapsed for a short test period!