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Necessary measurement equipment:
AM Signal Generator, Distortion Meter, Oscilloscope, Digital Volt Meter (DVM)
(A) VT Adjust
AM Signal Generator Setting:
1) Adjust AM Frequency of RX-975 to 520 kHz.
2) Connect (-) terminal of DVM with GND (or chassis) and connect (+) terminal with jumper J704 (VT
CHECK) and measure voltage. (Low Frequency VT)
3) Adjust VT to 1.2 volts with T-702 (AM-OSC Coil).
*In case of European version, AM frequency range is 522 kHz ~ 1611 kHz. So, adjust VT to 1.0 volt at 522
kHz. (Low Frequency VT)
(B) Output Level Adjust
AM Signal Generator Setting: Modulation; 30 %, Frequency; 400 Hz, Output Level; 84 dB
RX-975 Setting: AM Frequency; 600 kHz
1) Turn AM Signal Generator Modulation On.
2) Adjust output level to maximum point with T701 (AM-ANT Coil).
3) Adjust AM Signal Generator & RX-975 AM Frequency to 144 kHz and measure output level.
4) Adjust output level to maximum point with TC701 (WHITE trimmer).
5) Repeat above 2)~4) steps 2~3 times until adjusting to maximum output levels.
6) Adjust AM Signal Generator & RX-975 AM Frequency to 1000 kHz and measure output level.
7) Adjust level to maximum position with T703 (AM-IFT).
*In case of European version, AM Frequency Step is 9 kHz. So, change the standard frequency as below:
522 kHz as 520 kHz
1404 kHz as 1400 kHz
999 kHz as 1000 kHz
(C) TUNED Level Adjust
AM Signal Generator Setting: Modulation; 30 %, Audio Frequency; 400 Hz,
Radio Frequency; 1000 kHz Output Level; 84 dB
RX-975 Setting: AM Frequency; 1000 kHz
1) Turn AM Signal Generator Modulation On. (Make sure if Output level is 84 dB)
2) Adjust VR701 (AM-ADJ) up to the moment where 'TUNED' indicator turns OFF & ON again.
3) Confirm if 'TUNED' turns OFF when decreasing the output level of AM Signal Generator slowly from 84 dB
to 80 dB.
4) Push RX-975's TUNE UP or DOWN button "long" at AM Signal Generator Output Level 84 dB and start
Auto Search.
Confirm if search stops at AM Frequency 1000 kHz. (Check with both of High Frequency to 1000 kHz
search, Low Frequency to 1000 kHz search)
*In case of European version, AM Frequency Step is 9 kHz. So, check above steps with 999 kHz instead
of 1000 kHz.
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