HP 5326A - Page 20

Model 5326/27A
Operation
Figure 3-4. Front Panel Controls and Indicators (Continued)
g. FREQ C - Similar to FREQ A, except
sets counter to measure frequency applied to
INPUT C jack. 50-ohm input impedance.
5 V rms/7.5 V peak maximum input. Fre¬
quency range is 0 to 550 MHz prescaled or
1 kHz to 50 kHz direct. For the 5326B, the
frequency range is 0 to 50 MHz. See
INPUT C.
5. T IME BASE ‘'MULTIPLIER switch. The
function of the switch changes with each
mode of operation:
a. TOTALIZE - Determines scaling
factor for input signal prior to counting.
b. PERIOD AVG A - Selects number of
periods to be averaged.
c. T.I. AVG A to B - Selects number of
time intervals to be averaged.
d. T.I. A to B - Selects scaling factor for
internal oscillator signal.
e. PERIOD A - Selects scaling factor for
internal oscillator signal.
f. FREQ A and FREQ C - Sets gate time.
6. S LOPE switch. Permits triggering on positive
or negative slope of input signal.
7. A C-DC switch. Selects direct or capacitor
coupling for input signal. Minimum input
frequency on AC setting is 20 Hz.
8. A TTEN switch. Selects attenuation for input
signal. Used in conjunction with LEVEL
control to set input triggering point. Maxi¬
mum input: 250 V rms on all ranges except
25 V rms on XI range above 50 kHz. Recom¬
mended input is 0.1 V rms to 2 V rms times
ATTEN setting.
9. L EVEL control. Used in conjunction with
ATTEN switch to determine voltage at which
triggering occurs. With XI attenuator
setting, level is variable ±3 V; on X10, ±30 V;
and X100, ±300 V.
10. I nput jacks. Input jacks to Channels A and B.
Input impedance is l MR shunted by less than
25 pF. By using a 10 to 1 divider probe, input
impedance can be increased to 10 MG.
11. T rigger lamps adjacent to input jacks indicate
when amplifier triggering occurs.
12. C HK-SEP-COM-switch. (Check-separate-
common)
a. CHK - Connects internal 10 MHz time
base to Channels A and B circuitry to check
that unit is functioning. No indication in T.I.
or T.I. Avg; ignore displayed digits in period
average.
b. COM-SEP - Connects A and B inputs
in parallel when set to COM position. When
applying two separate inputs, set switch to
SEP. When set to COM, input impedance is
500 kQ shunted with less than 50 pF.
13. C (count) light. Lights when counter’s main
gate is open. For short-duration gate times,
the annunciator circuits include a 50 ms one-
shot MV to allow a visible flash of the C light.
14. * (asterisk). Indicates that proper units are
not displayed with combination of function/
time base selection. To interpret display, add
a zero to the right of least significant digit
displayed on the counter.