SBE SB-36 OPERATION MANUAL
Output of the receiver buffer transistor TR-20 is coupled to the wiper
arm of potentiometer VR-12 located in the receiver balanced detector
circuit.
5.3.5.2 VFO Oscillator
The VFO Oscillator uses a field effect transistor TR-3
(*)
as the oscillator
and TR-31 as the buffer transistor. The output of TR-31 is connected to
transistors TR-32 and TR-48.
(* Typo. Should be TR-30.)
The output of transistor TR-32, VFO information, is applied to the
counter circuitry in the SB-36 Transceiver.
The output of transistor TR-48 is VFO injection which is applied to the
emitter of mixer transistor TR-11.
The VFO operates on a frequency of 5.0 to 5.5 MHz.
Diode D-211 is a variable capacitance Diode connected in parallel with
C-120. Diode D-211 is switched into the circuit by the RIT selector
switch and the main relay contacts to shift the VFO frequency when
capacitor VR-602 is varied from one extreme to the other.
<Figure 5.43 Block Diagram of Counter Unit >
5.3.5.3 High Frequency Oscillator
The SB-36 has seven high frequency crystals used in the HFO
oscillator circuitry. The relationship between the transceiver operating
frequency and the HFO crystal frequency is shown on Table 5. 2.
HFO oscillator transistor TR-10 is crystal controlled by one of the seven
crystals selected by the band switch. Output of HFO transistor TR-10 is
coupled to the base of pre-mixed transistor TR-11. Output of pre-mixed
transistor TR-11 is coupled to either the grid of the transmit mixer tube
V-1, or the cathode of the receiver mixer tube V-3.
NoobowSystems Lab. Tomioka, Japan 2003 http://www.noobowsystems.com/ Page 26 / 56
To Next Page
Loading...
