despite your best effort, you cannot solve a problem with your radio, kit repair services
are available through Vectronics. See the warranty on the inside front cover for complete
instructions.
(12 Theory of Operation and Technical Specifications)
Technical Circuit Description:
The VEC-1016K is a sensitive voltage-tunable dual-conversion NBFM receiver that
includes an effective squelch circuit and gated AF-amplifier IC for speaker operation.
Incoming signals are filtered through a bandpass filter at L1/L2 to reduce out-of-band
interference, then boosted by low-noise preamplifier Q1. Q1 is series-matched to the
input of U1.
U1 is a Motorola device that perform nearly all receiver functions for the radio. The first
LO (local oscillator) is voltage-tuned by a temperature-compensated varactor diode built
into the receiver chip. Signals are converted in the receiver's DBM 1st-mixer stage down
to 10.7 MHz, the radio's 1st-IF. Here, they are fed through a roofing filter (FL1) to
reduce in-band interference. The second LO, crystal-controlled at 10.245 MHz, drives
the 2nd mixer for converting signals to 455 kHz. FL2 establishes the radio's message-
channel bandwidth prior to 100-dB of signal amplification and limiting in the 2nd IF.
Signals are demodulated by quardrature detection, and recovered audio signals are
preamplified to line level by U1's output stage. Audio is then sent to the receiver's
volume control and to AF amplifier U2.
In addition to processing FM signals, U1 also measures signal strength through log-amp
RSSI circuitry. RSSI output is sent to a built-in op-amp comparator, where signal
strength is compared to a reference level set by the radio's squelch control. The
comparitor then generates a logic signal to operate the "mute" pin of audio amplifier U2
for squelch action.
Audio is supplied to U2 via the radio's volume control. Here, audio signals are contoured
for frequency response and amplified to speaker-level. The output of U2 is fed to a
speaker/phone jack.
Technical Specifications:
Tuning Range
48.2-50.0 MHz (approximate)
Sensitivity
.5 uV typical for 12-dB sinad
Selectivity
20-kHz
message-channel
bandwidth
AF Output
60 mW into 8-ohm load
Current Drain
15 mA squelched, 40 mA on voice peaks
Power Source
9-v flatpack battery
