Parts List

Enhanced AM/FM Synthesizer Instruction Manual OS(R/T)-3(A/H) 29 - 470 MHz 2-7
In transmitters, the synthesizer operating frequency is the transmitter operating frequency; however,
for receivers, an IF Offset correction factor must be added to or subtracted from the synthesizer
operating frequency in order to determine the actual receive frequency. For VHF and UHF
Receivers, the IF Offset correction factor is 21.4 MHz, while for 800 and 900 MHz Receivers it is
45 MHz. Refer to Channel Designation Table documentation for simplified channel number and
frequency information.
2.4.2 Frequency Select Handle Frequency Control
In AM Receiver and Transmitter modules so equipped, the Frequency Select Handle (FSH)
replaces the normal Front Panel handle and allows direct Front Panel selection of the operating
frequency. Operation of the FSH is enabled by setting all external CHANNEL SELECT lines to
‘1111’ (i.e. all lines jumpered to +9.5 Vdc). The FSH user interface consists of three pushbuttons
plus an 8-digit dot matrix display. The FSH module communic ates with the synthesizer through a
standard 2-wire serial interface (9600 Baud, 8 bits, no parity, 1 stop bit) using simple ASCII
command protocols. On power up or on any key press, the synthesizer is interrogated by the FSH
for the current channel number and corresponding channel frequency, and this information is then
briefly displayed on the FSH display. The frequency may be either incremented or decremented
from the displayed value by pressing the Frequency Increase È or Frequency Decrease Í
button, as appropriate. For more detailed operating information, refer to the "Frequency Select
Handle Instruction Manual".
2.5 Synthesizer Base and Frequency Increment Table
The OS-3A/H Synthesizer operates in frequency increments of 5.0/6.25 kHz, 12.5 kHz or 25 kHz
depending on the particular model and band of operation. The Base Frequency for any given
synthesizer model is the lowest frequency generated.
Model Number Freq. Range Base Frequency Freq. Increment
OST-3H035 29 - 38 MHz 29 MHz 5.0/6.25 kHz
OST-3H045 38 - 50 MHz 29 MHz 5.0/6.25 kHz
OSR-3H061 50.4 - 71.4 MHz 50.4 MHz 5.0/6.25 kHz
OST-3A128 118 - 138 MHz 118 MHz 25/8.333 kHz
OSR-3A149 139.4 - 159.4 MHz 139.4 MHz 25/8.333 kHz
OST-3H141 128 - 152.6 MHz 128 MHz 5.0/6.25 kHz
OST-3H162 150 - 174 MHz 150 MHz 5.0/6.25 kHz
OSR-3H141 128 - 153 MHz 128 MHz 5.0/6.25 kHz
OSR-3H162 150 - 174 MHz 150 MHz 5.0/6.25 kHz
OST-3H418 406 - 430 MHz 406 MHz 12.5 kHz
OST-3H460 450 - 470 MHz 406 MHz 12.5 kHz
OSR-3H440 427.4 - 451.4 MHz 427.4 MHz 12.5 kHz