SG-2000 MANUAL
155
The SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
©1995, SGC, Inc.
TEL: (206) 746-6310 FAX: (206) 746-6384
23.1.10
20 dB Attenuator Check
A 20 dB Attenuator is selectable in receive mode by pressing the 20 dB ATTEN
key, and is enabled automatically when in transmit mode.
RX: To check the attenuator in receive mode, set the radio to 10,000.0 KHz, A3J,
USB, VOC, SPK, with AGC at minimum and RF generator to 10,001.0 KHz,
.5µV connected at SG-2000 RF In/Out. Note the audio level on the dB meter
attached to J301 Audio Out.
Engage the Attenuator on the radio and note the indication of the dB meter.
The attenuator should produce a 20 ±2 dB attenuation of the audio signal at
J301 Audio Out
TX: To check the attenuator in transmit mode, turn the attenuator off and
replace the RF generator with the dummy load.
Change mode of transmit on radio to A3J.
Monitor IC101 pin 1 with a voltmeter.
Key the radio in transmit. The voltage on IC101 pin 1 should change from < .5
VDC to 10 VDC, indicating that the Attenuator is engaged automatically while
in transmit.
23.1.11
AGC Adjustment
Turn the radio on and program the
frequency to 10,000.0 KHz A3J USB VOC SPK.
Apply .5 µV 10,001.0 KHz at the RF In.
Attach the scope and dB meter to J301 Audio Out. You should be able to hear
on the speaker and monitor on the dB meter and scope a 1 KHz tone.
Adjust R286 to approximately half value and note the value of the dB meter
reading.
Increase the RF In signal by 90 dB (32 mV RMS) and note the value of the dB
meter reading. The increase of Audio Out should not be more than 5 dB and
the scope signal should increase without distortion.
In the event of failure, refer to the Receive troubleshooting section.