FCC ID: K66FT-857
Operating Manual
Vertex Standard Co., Ltd.
29
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When done, press and hold in the [F] key for one second to save the new setting for the Microphone Gain.
1) The AM carrier level is preset to 25 Watts during alignment at the factory, and should not require
further adjustment. It is important to remember that AM transmission requires that power must be
distributed among the carrier and voice sidebands; therefore, if excessive carrier power is used, there
will be insufficient power available for the information-carrying voice sidebands.
2) The [TONE] switch on the back of the MH-31A8J microphone provides adjustment of the microphone’s frequency
response. Setting this switch to the “2” position will roll off some of the bass response, resulting in improved “talk
power” in many instances. The “1” position is primarily used in countries like Japan, where vowel sounds are of
critical importance in conveying information; in Western languages, consonant sounds (which are rich in high-
frequency components) are frequently more important.
VOX Operation
The VOX system provides automatic transmit/receive switching based on voice input to the microphone. With the VOX
system enabled, you do not need to press the PTT switch in order to transmit.
1. Press the [F] key momentarily, then rotate the MEM/VFO CH knob, as needed, until Multi Function Row “d” [RPT,
REV, VOX] appears on the display.
2. Press the [C](VOX) key to activate the VOX circuitry. “Parentheses” will appear on the both sides of the “VOX”
indication, and the “VOX” icon will appear on the display.
3. Without pressing the PTT switch, speak into the microphone in a normal voice level. When you start speaking, the
transmitter should be activated automatically. When you finish speaking, the transceiver should return to the receive
mode (after a short delay).
4. To cancel VOX and return to PTT operation, again press the [C](VOX) key. The parentheses and “VOX” icon will
disappear, signifying that the VOX system has been turned off.
5. The VOX Gain may be adjusted, so as to prevent accidental transmitter activation in a noisy environment. To adjust
the VOX Gain:
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While still in Multi Function Row “d” [RPT, REV, VOX], press and hold in the [C](VOX) key for one second.
This is a “hot key” feature which will instantly recall Menu Mode No-088 [VOX GAIN].
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While speaking into the microphone, rotate the DIAL to the point where the transmitter is quickly activated by
your voice, without causing background noise to activate the transmitter.
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When you have selected the optimum setting, press and hold the [F] key for one second to save the new settings and
return to normal operation.
6. The “Hang-Time” of the VOX system (the transmit-receive delay after the cessation of speech) may also be adjusted
via the Menu. The default delay is one second. To set a different delay time:
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Press and hold in the [F] key for one second to activate the Menu mode.