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:
FX-146
•
5
SPECIFICATIONS FOR THE RAMSEY FX-146
General:
Frequency Range: Any 20 MHz segment between 140 and 180
MHz
Tuning: Diode-programmable PLL synthesis 12 front
panel selected frequency pairs, easily
expandable by switches, microprocessors,
computers, etc.
Programming: 5 KHz steps with programmable offsets
Transmit Offset: Programmable: Simplex, +1.2, -1.2, Aux
Mode: NBFM
Packet (Data) Operation: All rates incl. 9600 baud . 5-pin DIN jack
(TXD, RXD, PTT, +12VDC, GND)
Packet RX Audio: Speaker, discriminator or true FSK
Power Requirement: 13.6V DC +/-10% (Negative ground)
Power Consumption: 1.0 A Transmit (for 5 watts RF output) 200
ma. (Receive, no signal)
Antenna Impedance: 50 ohms
Microphone Impedance: 600 ohms or high impedance
T-R switching: PIN diodes
PTT circuit: Solid State (for standard ICOM-type
speaker/mic connection)
Semiconductors: 10 IC's, 16 transistors, 24 diodes (plus
programming diodes)
Transmitter:
Final Power Output: 4-6 watts RF
Final Output Stage: MRF237 or equivalent
Modulation: True direct FM
Max frequency deviation: +/- 25 KHz, +/- 5KHz NBFM
Modulation distortion: Less than 5%
Receiver:
Circuitry: Double-conversion superhet
First IF: 21.4 MHz
Second IF: 455 KHz
Sensitivity: 12 db. SINAD less than 0.35 uv
Selectivity: 7 KHz (-6db.), 15 KHz (-60db.)
Squelch sensitivity: Less than 0.25 uv
Audio output: More than 2.0 watts
Circuit access points: COR, PL tone input, FSK demod. +12V,
+8V, +5V, PLL programming.