CHAPTER THREE
For Tape Search operation see TM Option Description, TM 02/02A, which is located in
Appendix A.
3.9 EXTERNAL FREQUENCY INPUT OPERATION
An External Frequency (External Oscillator), any integer of 1 through 10 MHz (1, 2, 3 MHz,
etc.) can be input to the TM7000 at rear panel BNC connector J5, and may be used to operate the
TM7000 in lieu of the internal oscillator. This input must be TTL Square Wave or Sine Wave
with a minimum amplitude of 1 volt Peak-to-Peak and a maximum of 5 volts Peak-to-Peak into a
50 Ohm load.
When an External Frequency (External Oscillator) is input to the TM7000 via J5, the External
Frequency input is automatically used. When it is removed, the Internal Oscillator is
automatically selected for use. In order for this feature to operate, an internal jumper (J22) must
be selected as shown below:
J22
123
EXT. OSC.
INPUT ENABLED
Note: This rear panel BNC is also used for 10MHz Sine Wave Output Operation (See
Section 3.10), so it is important that the above jumper be selected for the desired
feature. External Oscillator Input Enabled is the factory default setting for this jumper.
3.10 10MHZ SINE WAVE OUTPUT
On rear panel BNC connector J5, the TM7000 can generate a 10MHz sine wave. This sine wave
is derived and buffered from the internal oscillator (whichever is installed). In order for this
feature to operate, an internal jumper (J22) must be selected as shown below:
J22
123
10MHz
OUTPUT ENABLED
Note: This rear panel BNC is also used for External Frequency Input Operation (See
Section 3.9), so it is important that the above jumper be selected for the desired feature.
The level (amplitude) of the 10MHz output can be adjusted using potentiometer R184. See
Figure 2.2 in Chapter Two.
3-26 TM7000 TymMachine TCG/T (Rev D) Symmetricom, Inc.
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