Hewlett-Packard Model 105A/B Quartz oscillator

The Hewlett-Packard Model 105A or Model 105B Quartz Oscillator is a light and compact precision quartz oscillator for frequency and time standards. Either oscillator may be operated from 115V or 230V ac power or from an external 22 to 30 Vdc source; the Model 105B also has an internal sealed-cell, nickel-cadmium battery that can provide up to 8 hours standby power if ac line power should fail.

All of the Model 105A/B output frequencies are derived from the basic 5 MHz frequency of a quartz crystal oscillator contained in an oven to redupe the effect of ambient temperature on its frequency. The 5 MHz output is connected to front- and rear-panel connectors and to a regenerative pentade divider to produce the 1 MHz output signals. The 1 MHz divider output is fed to front- and rear-panel connectors and to a regenerative decade divider to produce the 100kHz outputs. The rear-panel CLOCK output connector can be connected to either the 100kHz or 1 MHz clock output circuit on the 100 kHz Divider Assembly.

A dc voltage derived from each sine wave output is monitored by the CIRCUIT CHECK meter when the CIRCUIT CHECK switch is set to the position indicated by that output frequency. In the remaining switch positions (SUPPLY, +18.7 V, and OVEN), the meter monitors (respectively) the +24V supply, the + 18.7 V supply, or the current through the proportionally controlled oven heater. For all CIRCUIT CHECK switch positions, the normal meter indication is "80", but the OVEN indication may vary slightly from this due to changes in ambient temperature.