Hewlett-Packard 5216A 12.5MHz Frequency Counter in Arlington, Texas For Sale

Nice little 7-digit Frequency Counter from xxxx-xxxx era, with smaller Nixie tubes. Range up to 12.5MHz. Seems to work fine.
Manufacturer: Hewlett-Packard
Model: xxxxA
Year: xxxx
RANGE: 3 Hz to 12.5 MHz.
DISPLAY: Long-life Nixie with display storage and blanking.
Digits: 7
Logic: TTL
An early all-IC counter. The main ICs used in this counter are MSI TTL decade counters and NIXIE drivers. They are proprietary HP devices having some additional functionality not found in the standard xxxx / xxxx devices.
The additional functionality of the ICs is for leading-zero blanking in the display. The decade counter ICs have an 11th state (decimal 15) to represent blanked-zero. The NIXIE driver IC blanks the NIXIE upon input of 15. Upon reset the decade counters are set to the blanked-zero state. Any clock activity on a given decade (digit) unblanks that decade. At the end of the gate/count period leading zeroes are still blanked while lower-order zeroes have been unblanked. This scheme can result in some briefly idiosyncratic displays when changing the function mode.
An innovation is the zero suppression capability featured in both new integrated counters. All insignificant zeroes (i.e. those to the left of the most significant digit) are suppressed and the columns at the left side of the display are dark until they have received a carry pulse from the preceding decade counter. Although it conveys no new information, zero suppression provides a simplified and uncluttered readout with less chance for errors in reading the display.
Whether any given decade will have zero suppression at any given time depends on where the corresponding digit is in relation to the decimal point on the display. Digits to the right of the decimal point and the first digit to the left would not have their zero-suppression circuits enabled. There is also a rear-panel switch for overriding zero suppression in all decades. When a decade is not to have zero suppression it receives a control signal from logic circuitry which monitors the position of the decimal point and the rear-panel switch.
Also has a rear-panel connector for interfacing with a computer, although it pre-dates the HP-IB or IEEE-488 standards.
DISPLAY TIME: 50 ms to 5 s or hold until manual reset.
INPUT SENSITIVITY: O.Ol V rms sine wave, max. sensitivity; 30 mV peakpulse, min. pulsewidth 4 0ns. Front panel sensitivity control - step attenuator (0.01, 0.1, 1, 10V settings).
IMPEDANCE: Approx. 1 Mil shunted by 50 pF.
OVERLOAD: Input voltage should not exceed 60dB above attenuator setting or 300 V rms (damage level).
CONNECTORS: At both front and rear panels.
SIGNAL POLARITY: Front panel trigger level control allows counting either positive or negative input pulses.
OPERATING TEMPERATURE RANGE: 0°C to +50°C.
TIME BASE FREQUENCY: 10 MHz.
EXTERNAL TIME BASE INPUT SENSITIVITY: 1V rms sinewave into xxxx ohms (10V rms maximum).
RANGE: 1 kHz to 2 MHz, sine wave.
TIMEBASE OUTPUT: 1MHz, 3V p-p minimum open circuit: source impedance is xxxx Ohms
FREQUENCY MEASUREMENT RANGE: 3 Hz to 12.5 MHz.
WEIGHT: Net. 7 Ibs. Shipping Weight: 10 lbs.
POWER REQUIREMENTS: 115/230 V ±10%, 50 to xxxx Hz, 20 W max.
xxxx PRICE: HP Model xxxxA, $925.