DANIELS
ELECTRONICS LTD.
TM
3-14
IM10-VR3H040-AB VHF Enhanced Extra Wideband Receiver Instruction Manual
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.
3.4.2
Synthesizer Base and Frequency Increment Table
The OS-3A/H Synthesizer operates in frequency increments of 5.0/6.25 kHz. 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
3.4.3
5.0/6.25 kHz Channelization.
All Daniels VHF synthesizers have been designed to generate frequencies in both 5.0 kHz and
6.25 kHz channel increments. BCD channel switch settings from
0000 to 4999
will therefore
select operating frequencies with
5.0 kHz
increments, while BCD switch settings from
5000 to
9999
will select operating frequencies with
6.25 kHz
increments. Calculation of the operating
frequency for VHF synthesizers capable of 5.0/6.25 kHz channelization is determined as
follows:
• BCD switch settings from
0000 to 4999
: Multiply the switch setting by 5.0 kHz and
add the result to the synthesizer base frequency.
Example: An OST-3H141 synthesizer has a base frequency of 128 MHz. The
selected channel number is 0988. The synthesizer output frequency is:
((988 x 5 kHz) + 128 MHz) = 132.940 MHz
• BCD switch settings from
5000 to 9999
: Subtract 5000 from the switch setting.
Multiply the result by 6.25 kHz and add the result to the synthesizer base frequency.
Example: An OSR-3H162 synthesizer has a base frequency of 150 MHz. The
selected channel number is 7205. The synthesizer output frequency is:
((7205-5000) x 6.25
kHz) + 150
MHz) = 163.78125
MHz
