FCC ID : AK8NTM30
Model : NTM-30
Part TX
Circuit system of ICB-U655(Part TX) is Narrow band FM with varactor modulation.
The frequency is made with Phase Locked Loop (PLL) synthesized oscillator composed
of VCO1 and IC3, and will take a route to Q3, Q4, Q5, Q6 (P.A), Low Pass Filter and
finally to the Antenna for the transmission. The transmission frequency is made by
standard oscillator (Crystal Oscillator :X1 21.25MHz) and is adjusted by trimmer
capacitor (C53). The transmission output is composed of the method of limiting the
voltage given to Q4, Q5, and Q6, and is adjusted by RV107. The voltage limitation is
controlled with IC103, Q124, and Q125. The aural signal picked up with the
microphone (MIC101) is amplified by Q118 and sent to IC106. Amplifies, and pre-
emphasis, LPF, and Modulation limit amplifier are composed in IC106. The IC106
output is adjusted maximum frequency deviation with RV103 to becoming in the
standard, and is sent to varactor in VCO1 through LPF. Finally, modulated wave is
transmitted through Antenna.
SEARCH SYSTEM
At the standby
The channel is scanned while confirming whether there are both the 1kHz and the tone
signal. The tone signal is CTCSS(Continuous Tone Controlled Sub-audible Squelch)
signal set beforehand. When both 1kHz and the tone signal are detected, the scanning is
stop. The 1kHz signal through the Amplifier (Q101) and the Schmitt-trigger (Q102,
Q103) is sent to the System Controller (IC101). The 1kHz signal is detected by the
System Controller and the tone signal is detected by IC109.
