AMX TXC16 Plus Specifications download pdf (Page 164)

SG-2000 MANUAL 157

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

23.1.15 Transmit Calibration

The following steps will adjust and verify that the RF out from the Exciter will

drive the input of an SG-2000 LPA and produce 150 W (ALC disabled) into a

dummy load. The audio signal used to produce RF Out from the Exciter can be

selected between the 30 mV microphone input, CW tone generator on the

Exciter or 600? audio generator attached at J301 Audio In. All sources should

be adjusted for the same level at TP203 and produce the same Exciter RF Out.

Attach a 50 ? dummy load to J102 RF Out. Reduce ALC response to minimum

by turning R41 and R42, on the LPA, fully clockwise.

Set R119 to mid setting and R121 to max value (fully counterclockwise).

Set the radio in receiving mode, A3J, USB, VOC, 10 MHz.

23.1.16 Microphone Level Adjustment

Inject 1 KHz, 30 mV RMS into the mic jack on the head.

Key the radio in transmit and verify with a scope the following levels:

• J504 pin 9 and 10 to GND: 1.5 Vpp, no distortion. Adjust R66 (microphone

gain) inside the head if this value is different.

• Using the scope to monitor TP203, verify that the signal is 300 mVpp, for

Rev F and earlier boards. For Rev H and later boards, adjust R316 to get

150 mVpp on TP203.

23.1.17 CW Level Adjustment

Note: The SG-2000 produces a J2E (A2J old denomination) type of CW

transmission. This is done by substituting microphone signal from the head

with a 1000 Hz tone in an A3J configuration. The tone is produced on the

Exciter board and its level is adjusted by R610.

With the radio in receive, CW, USB, VOC and the Exciter RF Out connected to

a 50? dummy load, key the radio in transmit and adjust R610 to 150 mVpp (300

mVpp for exciters of Rev F and earlier) at TP203.

Check for: TP301 = 240 ± 10 mVpp (for Rev H and later PCBs)

TP605 = 200 ± 10 mVpp (for Rev H and later PCBs)

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AMX TXC16 Plus Specifications Page 164