MFT-20 DSB Transceiver Kit
Page 21
RX Gain Potentiometer P1 (Volume)
Install the RX Gain potentiometer P1 as shown in the picture.
You may prefer to mount this component on the front panel, off the circuit board. There is no problem in
doing this if the wires are short.
Bend and break the small tab protruding and will not bother when you screw on the front.
TUNE Potentiometer P2 (Tuning)
Install the Tune potentiometer P2 as shown in the picture.
This is the tuning knob which it will cover about 50-60KHz of the band. To tune in with certain comfort we
recommend using a control button at least 20-30mm diameter.
ADJUSTMENTS AND TESTS
Preliminary adjustment
- Adjust P3 (mic gain), P4 (carrier suppression) and P1 (RF gain/volume potentiometer) to mid-position.
- Connect a speaker or headphones to the “SPEAK” pins on the circuit board.
IMPORTANT: Use a high-quality speaker box. A bad speaker will make ineffective the operation of the
transceiver.
- DO NOT yet connect a microphone.
- Apply power supply voltage (12-14V) to the “12V” header pins on the circuit board.
- Turn the volume to maximum; you should hear a hissing noise in the headphones or speaker.
Note: For the VFO to reach its maximum stability it is recommended to wait about 5 minutes.
L4 and VXO frequency coverage
Solder the pigtails of L4 in place on the circuit board.
Connect a frequency counter to the “VXO” header. If the input of the frequency counter is low
impedance, insert a 470 ohm (or greater) or a small value capacitor (try with 22pF or less) between the
frequency counter and the header to reduce the interaction with the VXO.
