User's Guide

3-2 Enhanced AM/FM Synthesizer Instruction Manual OS(R/T)-3(A/H) 29 - 470 MHz
The corresponding internal synthesizer jumper settings are:
Digital Board
• Jumper JU2 not installed 9.6 MHz internal frequency reference selected
• Jumper JU1 installed AM Multichannel mode selected
Analog Board
• Jumper JU1: 'B' position Internal frequency reference selected
• Jumper JU2 not installed Internal frequency reference selected
3.5 OS(R/T)-3(A/H) Synthesizer Alignment
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3.5.1 General
Under normal circumstances (i.e. a change in operating frequency within the synthesizer’s
maximum tuning range), synthesizer alignment is accomplished with the synthesizer installed in the
MT-3 Receiver IF/Audio Board or the MT-3 Transmitter Main Board. The alignment procedure
involves setting the internal TCXO reference frequency (if one is installed and the internal
reference option is enabled). This step is described in "Reference Frequency Alignment", section
3.5.5.5. A change in operating frequency from the ini tial factory setting that exceeds the
synthesizer’s maximum tuning range (Refer to Specifications section 1.3) requires a more involved
alignment procedure as described in sections 3.5.2 to 3.5.5. Conversion of a synthesizer from
internal reference to ex ternal reference or vice-versa is accomplished through selection of jumper
JU1 A or B, as appropriate and JU2 (Refer to section 3.5.6).
3.5.2 Synthesizer Test Points
Analog Board Component Layout (Top)
Common to all synthesizer family members.
TP1 +8.0 ± 0.3 Vdc. U6 positive regulator output.
TP2 +5.0 ±0.1 Vdc. U7 positive regulator output.
TP3 +5.0 ±0.1 Vdc. U8 positive regulator output (always on).
TP4 PLL error voltage. Normal range is +0.5 to +4.5 Vdc (depending on frequency).
Nominally adjusted for +2.3 Vdc (via C24) for center channel .
UHF/VHF versions employing integrated VCO modules (OSR-3H440,
OST-3H418, OST-3H460, OSR-3A149, OST-3A128) require no adjustment.
Digital Board Component Layout (Bottom)
TP1 +5.0 ±0.1 Vdc. U2 positive regulator output (controlled via pin P2-4).
TP2 Microcontroller E clock. 2 MHz logic level square wave.