Yaesu FR-50B, Инструкция по эксплуатации

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Page 9 of 22
In the case of adjusting while communicating, turn the BFO PITCH
to give the same tone from the received signal and monitored
signal. Note that the BFO PITCH control can be used to provide a
degree of "off-set" tuning in the transceive mode.
ALIGNMENT PROCEDURE
1. Test Equipment Required
A. Circuit tester
B . VTVM & RF probe
C. Standard signal generator (SSG)
{ To protect your precious signal generator please make sure you AC
couple to the receiver. VTVM refers to a Vacuum Tube Volt Meter –
these instruments have an input resistance of around 11 M
Ω
, most
modern Digital Mustimeters have a input resistance of 10 M
Ω
- this
will slightly affect the voltage measurements made as per Table
1.}
2. Voltage Measurements { to assist with fault finding }
Use the VTVM to measure voltages. Refer to Table 1 for approximate
values. A circuit tester used for measurement will indicate some
lower voltages than those shown in the table.
{ 2bis. Resistance Measurements
To further assist with fault finding Table 2 contains expected
resistance measurements between ground and the indicated point in
the circuit. These measurements are made with the receiver
switched off (and preferably with the plug pulled out of the mains
socket)}
3. 455 kHz I.F. Alignment
Apply a 455 kHz signal to grid 1 of V3 (pin 1). Adjust MFl, MF2
and L7 for maximum "S" meter reading. Use care if adjusting MFl,
MF2. The adjusting screws have a fine thread and can be easily
damaged, if too much pressure is applied. However, re-adjustment
of these should not be necessary as there is little to get out of
order. {T
he filters in my receiver where not adjustable. }
4. 1st I.F. Alignment
Apply 5 173.9 kHz signal to grid 1 of V2 (pin 7). Adjust L6 (both
cores) for maximum "S” meter reading.
{L6 on m
y receiver had only one core and peaked satisfactorily }
5. Adjustment of 2nd Oscillator Output
Connect RF probe of VTVM to grid 1 of V3 (pin 1). Adjust the upper
core of Ll9 for 70% of maximum reading, and the lower core for maximum
reading.