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Q4: "I tried using my ACE Power Pacer cycler to check my Futaba transmitter battery and found it wouldn't work," wrote one reader. "Didn't I read something to the effect that most RC transmitter battery circuits contain a blocking diode that prevents you from measuring the battery voltage at the charging jack? Should I remove the battery from the transmitter for testing purposes?"

A4: Yes, you will have to remove the battery. I'm forced to do this with almost every brand of RC transmitter in my inventory.

However, that isn't the end of the world because most RC transmitters have an easy-access hatch cover at the rear of the case. You open the cover and can usually remove the battery pack with no difficulty.

Most transmitter battery packs also have a connector (provided by thoughtful manufacturers) that allows you to disconnect the battery pack from the circuit. The trick then is to obtain a mating connector that will allow you to attach the battery pack to your discharge testing device (or cycler).

Many RC manufacturers will sell you this necessary mating cable. Battery suppliers such as Batteries America and Radical RC also sell a variety of transmitter battery cables and connectors. Construct these adapters once, and you are set for the future.

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Q5: "I wonder about the term 'channel number,'" one reader wrote. "I see references to the channel number flags on the transmitter antenna, but then I noticed a receiver label that states 'FM 7 Channel Receiver.' Why is this?"

A5: The term "channel" or "channel number" actually has two meanings when it comes to the RC hobby. In 1982 the Federal Communications Commission granted a series of frequencies on 72 and 75 MHz (megahertz) for RC use. Each frequency was identified by a series of five digits, such as 72.010 MHz.

From the start it was realized that trying to memorize frequency numbers would be impossible, so borrowing from the television industry, AMA suggested that a channel number be assigned to each authorized RC frequency. For RC-aircraft purposes, channel numbers were assigned from 11 up to 60 (a total of 50). On 75 MHz, additional frequencies (therefore, additional channel numbers) were assigned for the use of surface vehicles such as RC cars and boats.

When you are at a flying field and are asked what channel you are operating on, the answer will be "I'm on 32," "I'm on 56," and so on. The channel number is an easy way to identify the authorized RC frequencies.

Separate from this definition is the term "channel functions" or "number of channel functions" when it comes to RC transmitters and receivers. When we flew in the early 1950s our control was usually limited to rudder. Back then we called that "single channel" control.

Later, when technology provided for more functions, we said that RC systems had "multichannel" capability. Each control function, such as rudder, elevator, aileron, and throttle, was called a "channel function." A "four-channel receiver" provided four controls for a model aircraft.

When the reader saw the decal indicating "FM 7 Channel Receiver," it meant that the receiver could impart seven control functions to the aircraft. This seven-channel reference has absolutely nothing to do with the channel number (two digits) displayed on the flag that hangs from a transmitter's antenna.

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