Yaesu FRG-100 Technical Supplement - Circuit Description
Circuit Description
This description, together with the block
diagram, is intended to provide a general
derstanding of the electrical functions of the
circuits of the FRG-100. Such an
standing is necessary for troubleshooting the
Refer to the
diagrams and
for specific component and wiring
details.
Front-End Stages
Incoming RF from the antenna
is
ered to the main unit after
through a
impedance transformer Tl004 (if
tenna is selected using the
switch)
and surge suppresser D1005, which removes
high
which might
otherwise darnage components in the
end. It is then low-pass filtered and
ated (if enabled). The received
is then
impedance transformed by transformer
T1018, then band-pass filtered to suppress
termodulation by Signals from other bands.
The correct bandpass
is selected by BCD
control Signals from the PLL unit, and
by Q1032
The
is
then once again impedance transformed by
T1005, before
the 1st mixer
The
then enters the
1st
mixer,
consisting
o f
along with the 1st
oscillator
output from the
unit (47.260 77.210
MHz) which has been amplified by Q1006
and low-pass filtered by
and
The
ing 47.21 MHz 1st mixer
through monolithic crystal filters
and
XF1002 ( 20 kHz BW) where other unwanted
mixer products are stripped away to
the filtered 1st IF Signal.
Stages
The filtered 1st IF
is then amplified
by
and applied to
2nd mixer
which
also receives the 2nd
generated
from 46.775 MHz crystal
and amplified
by
to
the 455 kHz
2nd IE When FM Operation is selected, a
tion of this 455 kHz
of the 2nd mixer
is buff er-amplified by
and delivered to
the optional
FM
00
for detection(when
installed) For other modes, the 455 kHz
is
through the noise blanker gate
D1014) and is then filtered
by ceramic filters CF1 001, CF1002, or CF1 003
(depending on selected mode) where other
are stripped away
Final IF
is provided by
Ql018, QlO17, and
fore the
is applied to buffer amplifier
and then enters
tion
For SSB and CW modes, the amplified IF
is applied to the
sisting of D1033, D1038,
and D1040
Here, it mixed with the
priate
for either LSB, CW
or USB from the DDS unit, having been
ered by Q1028. The detected
then
through a LPF consisting of
and
Cl141 before delivery to analog switch
4. The
enters the
filter
which functions as a low pass
for audio
before delivery to analog switch
For AM
another buffered output
from the 2nd IF is detected by D1032, the
output of which serves as both the detected
AM
and AGC. This
then
through the LPF formed by
and Cl130
before
to analog switch
and
on for audio
Aud io Amp iers
The low level detected audio in all modes
pass through mute switch
not
muted by the
control lines), and then
buffer amplifier
The
through another mute circuit
and is mixed with beeper audio
from the microprocessor having passed
through the LPF and
The mixed
audio is amplified by Q1034
to
drive a 4 8 loudspeaker or headphone.
The output from Q1034 is
by
VOL
00
Supplement