Yaesu FR-50B, Instruction Manual

Page: 10 / 22

Page 10 of 22
6. Alignment of VFO Scale
For correct alignment a 100 kHz marker is necessary, and if this is
built-in it should be used. Adjust coils at the low frequency end,
and trimmer condensers at the high end of each band for zero beat.
Repeat this adjustment for greatest accuracy. Note that turning of
cores or trimmers too far may lead to incorrect frequency by an
amount of ±100 kHz.
7. RF Alignment { alignment of the pre-selector }
Set mode switch (S3) to AM, band switch (S1) to 10m, and the
preselector (VC1) to mid-scale. With the main dial (VC2), tune in
a 28.5 MHz signal from the SSG. Adjust cores of L2 and L4 for
maximum "S" meter reading.
Set the band switch to 15m and tune in a 21.25 MHz signal from the
SSG, and adjust TC3 and TC8 for maximum "S" meter reading.
On 20 meters, with SSG output 14.25 MHz, adjust TC2 and TC7 for
maximum "S" meter reading.
On 40 meters, with SSG output 7.25 MHz, adjust L3 and L5 for
maximum "S" meter reading.
On 80 meters, with SSG output 3.5 MHz and preselector (VC1) at
“1”, adjust TCl and TC6 for maximum “S” meter reading. On this
band, the upper limit of the preselector range is about 3.8 MHz so
a slight sensitivity decrease results between 3.8 and 4 MHz.
During the alignment, keep the SSG output level down to the
minimum of that required. {
at least below -60 dBm }
{
TC4 and TC9 are used to adjust the AUX frequency, I have no idea
what TC? does }
8. Adjustment of Trap
Ll is a trap to prevent a spurious signal from entering directly
into 1st I.F. stage. Set the SSG output on 5 173.9 kHz and adjust
Ll for minimum “S” meter reading. Adjust Ll9 so that no beat is
heard from the speaker. This adjustment is unnecessary unless set
up for transceive operation.
9. BFO Alignment
Set mode switch (S3)to SSB/CW. Tune receiver to a non-modulated
signal from the SSG, adjusting for maximum "S" meter reading. Set BFO
PITCH to "0" and adjust Ll9for zero beat.
10. "S" Meter Zero Set
After removing antenna, adjust VR3 so that “S” meter indicates
zero. Note that the “S” meter will not read inversely due to the
installation of a diode. {
My receiver as well as the schematics I
have seen do not have this diode installed. }