Micro2R Operation; Setting Audio Levels; Configuring Micro2R For Your Radios - microHAM micro2R u2R User Manual

For optimum operation of micro2R the audio levels must be set properly. The function of each control was
described in the AUDIO MIXER and DVK sections of the manual.
About microphones and micro2R: In order to configure micro2R correctly, it is absolutely necessary to
understand the difference between electret and dynamic microphones.
A dynamic microphone consists of a small moving coil and a magnet. As sound moves the diaphragm,
the magnetic field in the coil changes producing a very small AC current which results in about 15
millivolts peak-to-peak at the of the typical transceiver. If a small voltage is applied to a dynamic
microphone, it requires more sound pressure to move the diaphragm and the output of the mic is
reduced. If the current through the coil is not limited, a dynamic mic can be damaged.
An electret mic consists of a capacitor with an electrostatically charged dielectric attached to the
diaphragm and a small amplifier. The voltage variation caused by sound on the electret capacitor is so
small that the amplifier is required before the output can be used. The amplifier requires a small DC
voltage ("bias") to operate and provides an audio signal of about about 500 millivolts peak to peak.
While dynamic and electret microphones each have their strong points, they are not directly
interchangeable. Where an electret mic will not work without a DC supply, a dynamic mic can be
damaged by that voltage. In addition, signal levels are very different with the typical electret mic
producing signal levels 20-60 times greater than that from a dynamic mic. Because of the differences,
one can not interchange dynamic and electret microphones without special consideration.
Most amateur transceivers are designed for use with dynamic microphones - this includes those made
by Elecraft, Kenwood, TenTec and Yaesu. On the other hand, Icom transceivers are designed for use
with electret microphones. When compared to other transceivers, Icom radios typically required a larger
audio input and have a DC voltage on their microphone line. Note: the Elecraft K3 can be configured for
either electret or dynamic microphones.

Configuring micro2R for your radios:

1. Open the top cover of micro2R and check the jumper for the internal microphone
preamplifier. Jumper has three pins. For dynamic microphones, so not close any
pins. For electret microphone that require bias on TIP (mono plug like Heil iC),
place a jumper on the top two pins (TIP position). For electret microphones with
stereo plug that expect to have bias on the ring (a typical computer or multi-media
microphone), place a jumper on the lower two pins (RING position).
2. Set the R1 (Radio 1) and R2 (Radio 2) microphone trimmers (located above
headphone isolation jumpers) and the preamp GAIN trimmer (located above
the microphone jumper) to the middle of their range.
3. Set the front panel TX1 and TX2 knobs to 12 o'clock.
4. Connect your microphone to micro2R and select Radio 1 for transmit.
5. Open Router's Audio tab and uncheck both "Disable audio switching on RADIO1"
and "Disable audio switching on RADIO2." Make sure the VOICE mode has
been selected on the Ports tab.
6. On the PTT tab, set "Generate PTT output" for both radios.
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6 - micro2R OPERATION

Setting Audio Levels

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