SGC SG-2020 User Guide

SG-2020 Transceiver

Test/Calibration Procedure

SG-2020 TEST DOCUMENT

This SG-2020 Test Document is divided into two sections:

Section One: Basic & Simple Test
Section Two: Full Test & Calibration

This test document is provided to SGC dealers, techni­cians and engineers who have full knowledge and experi­ence with electronics and HF radio communications. The
tests and calibration described must be performed using
appropriate, calibrated, good quality instruments.

Note that Section Two is not covered under the Warranty
of the SG-2020. Any information concerning this docu­ment must be executed in writing only. These procedures
are provided as informational only to assist qualified tech­nicians or engineers with field use and service of the SG­2020 transceiver.

“No Compromise Communications”

SG-2020 BASIC PERFORMANCE TESTS

The SGC factory test procedures as well as the test procedures detailed in the
ARRL Handbook chapter 26 can be used to fully measure the performance of
the radio. The following are simple tests which do not require laboratory test
equipment and can be used to determine if the unit is generally operating
properly.

1. Receiver Sensitivity:

The measurement of sensitivity with signal levels below one micro volt
requires a well shielded signal generator due to the very low level signal
involved. Inexpensive generators of the sort used by amateurs or for service
work leak signals which causes inaccurate readings at low signal levels.

By using a larger signal level and verifying the expected AGC response, a
reasonable sensitivity check can be obtained with an inexpensive signal
generator.

a. Set the SG-2020 to the desired frequency with mode USB and BW 2.2

KHz. Be sure to turn the RF gain fully clockwise.

b. Set the signal generator to the same frequency plus 1 KHz and set its

output level to 50 micro volts.

c. Verify that the 5 LED’s in the bargraph display are lit. If the bargraph

reads more than 2 LED’s below the expected value, the unit requires
service.

2. Transmit Quality:

Listen to the voice quality on another receiver being careful to avoid over­load. Most defects can be heard with critical listening tests.
A quantitative measurement of linearity requires a two-tone audio generator
with the results normally viewed on a spectrum analyzer. However, with
care it is possible to use an attenuator and receiver in place of the spectrum
analyzer.

3. Transmit Power:

The transmitter is connected to a power meter and dummy load. The mea­sured power is compared to the power setting of the SG-2020.

Note that the power meters usually sold for amateur use are not very accu­rate. A calibrated Bird or similar meter is needed for reliable results.

SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA

P.O.Box 3526, 98009 Fax: [phone] or 746-7173 Tel: [phone] or 1-800-259 7331

E-mail: [e-mail] Web site: http://www.sgcworld.com

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© 2001 SGC Inc

4. SWR Shutdown:

Transmit 20 watts in CW mode with no antenna connected. You should get
less than 5 LED’s on for forward power and full scale reading (all LED’s on)
for reverse power. as indicated by the bargraph display.

SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA

P.O.Box 3526, 98009 Fax: [phone] or 746-7173 Tel: [phone] or 1-800-259 7331

E-mail: [e-mail] Web site: http://www.sgcworld.com

3

© 2001 SGC Inc

SGC TEST DESCRIPTION

NOTE: Any adjustments made to the SG-2020, besides the R46 CW sidetone

adjustment are NOT covered by the warranty.

The following are tests performed on a fully assembled SG-2020 transceiver.

TEST EQUIPMENT REQUIRED

Audio Signal Generator

(Audio out applied to the microphone connector of SG-2020 under test)
RF Noise Generator
RF Sinusoidal Signal Generator
RF Spectrum Analyzer in addition to a RF Sweep Generator

(Connected through an attenuator of min. 35 dB to the dummy load output.)
Oscilloscope Tektronix 465B or equivalent
Current meter 0-1 Amp Range

Current meter 0-10 Amp Range
Voltmeter Fluke 77 or equivalent
Power Supply PS-10 or equivalent 10-amp power supply
Frequency Counter (connected to the vertical output of oscilloscope.)
Audio Distortion Analyzer (connected at the speaker/headphone jack)

Bird Wattmeter model 43 or equivalent.

1.0 L.O. PLL ERROR VOLTAGE

1.1 Connect voltmeter to TP3 and GND on the Exciter PCB.

1.2 Dial 29700.0 KHz on the display.

1.3 Verify voltage reading is less than 16 VDC. If not, adjust the spacing
between the windings on L18. Pull the windings together for a
lower-voltage reading or spread windings for a higher-voltage reading.

1.4 Change the frequency to 1800.0 KHz.

1.5 Verify new voltage reading is approximately 3 VDC.

2.0 ALIGN RECEIVE IF TRANSFORMERS

2.1 Connect signal generator to antenna input.

2.2 Connect voltmeter to AGC TP13 and GND on the Exciter PCB.

2.3 Set display frequency to 14150.0 KHz USB, signal generator to receiver
frequency +1 KHz and adjust output level of signal generator (typical­ly 10 µV) for 5 VDC reading on the voltmeter.

2.4 Adjust T3 and T4 for maximum AGC voltage, while reducing signal
generator output as necessary to keep AGC voltage near 5 VDC.

SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA

P.O.Box 3526, 98009 Fax: [phone] or 746-7173 Tel: [phone] or 1-800-259 7331

E-mail: [e-mail] Web site: http://www.sgcworld.com

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© 2001 SGC Inc