Specifications

FX 146 • 142
output by spreading the coils.)
*Common faults:
• Low supply voltage.
• Improper tuning.
• Improper output power measurement.
Receive Section Faults:
(manual pages ref. 20-21, assm 22-24, assm 30)
1. Poor or no receive. Lots of audio hash.
a. Check for proper VCO frequency.
b. Ensure pin diode D6 is forward biased (anode ~ 2.7VDC, cathode
~ 2.0 VDC) and pin diodes D2 and D7 are reverse biased (D2
anode ~ 0VDC, D7 anode ~ 0VDC, cathode ~ 2.0VDC).
c. Check preamp transistors Q2 and Q3 for proper operation. (The
Base lead on both transistors should be appox. .6 - .7 VDC)
*Common faults:
• Solder shorts between components.
• Improper value components. (There’s a few each of the 470 ohm
and 47K ohm resistors!)
2. No receive. Audio is completely quiet.
a. Check Q6. (Q6 turns off the LM-380 audio amp in transmit and
when squelched.) Q6 should be turned off during receive when
unsquelched. (approx. 0 VDC on the Base lead.)
Misc. Faults:
1. The darn thing is blowing fuses.
a. Check for a short to ground on one of the supply lines. (+12V,
+8V, +5V) You may have to remove a few components to isolate
the short.
2. Low receive audio, or low transmit audio.
a. Ensure correct connections between the speaker and microphone
jacks and the circuit board. (ex. The ground and speaker wires
are switched. Since the ground is common for the speaker and
mic on your average speaker-mic, you have just grounded the
audio output of your transceiver.)
If All Else Fails: