HP Car 3490A Pebformancechecks, Accommon.Moderejectiontest, Dcvoltmeterinputresistancetest, Test

Section V PEBFORMANCECHECKS Model3490A

5.22.ACCOMMON.MODEREJECTIONTEST.

5-23. An ac calibrator (hp- 7a5A) and an electronic counter (-hp- 53004) arerequiredfor this test.

a.Connect a I kCl resistor betweeninput High and Iow terminals, and connect High to Guard as sfiown in Figure 5-3.

b.Connectelectroniccounter to ac calibratoroutput and adjust calibrator frequencyto 60 Hz t O.l % if the 349OA is desigred for 60 Hz line operation, 50 Hz

!0.1 % if it is a 50 Hz model.

c.Before connectingac calibrator output to 3490A, set 3490A FLJNCTIONto DC. RANGE to I V. Note 3490A reading.

d.Connect ac calibrator to 3490A as indicated in Figure 5-3 and set output voltageto 70.7 Vrms (100 V peak).

c.Set 3490A FUNCTION to DC. RANGE to l0 V. shortInput. Note 3490A reading.

d.Disconnect input shortandconnectcalibratorto 3490A input. Adjust calibrator amplifier to 7.07 Vrms (10 V peak).

e.3490A reading should not vary more than I 00.316 V from reading noted in step c. This verifies normal-moderejection of )50 dB at 60 Hz (or 50 Hz), where:

Peakac superimposedvoltage

NMR= 20los

Effect on reading(volts)

5.26.DCVOLTMETERINPUTRESISTANCETEST.

5-27. A dc standard(hp- 7a0B) and a I MA !O.l% resistor(-hp-0698-6369)arerequiredfor this test.

e. 3490A reading should not change more than	Connect Guard to Input Low or domageto
0.00001 V from the readingnoted in stepc, verifyingac
common-mode rejection of 2140 dB at the frequency	the instrument may result.

specified(50 Hz or 60 Hz), using the formula givenin Paragraph5-21.

S24.ACNORMAL.MODEREJECTION			a. Connect3490A, dc standardand resistorasshown
			in Figure5-5.
	TEST.
5-25. AC normal-moderejectionis the ratio of the peak			b. Set 3490A FUNCTIONto DC, RANGE to lOV.
normal-mode voltage to the resultant error in reading.
An ac calibrator (-hp- 7454) and an electronicCounter			c. Connectjumper acrossI M,fl resistorasindicated.
(-hp- 5300A) arerequiredfor this test.		,-..	Adjust dc standardoutput to		10.0000V. Note 3490A
			reading.
a. Connect test equipment as shown in Figure 5-4.
			d. -Removejumper from I MQ resistor.3490A read-
Do not connect to 3490A input.		i^
			ing should not changemore than 00.0010V, verifying
b- Usingan electroniccounterasa monitor, adjustac			input resistance) l0 ro Q.
calibrator frequency for 60 Hz t 0.1 % if 3490A is
designedfor 60 Hz line operation,or 50.H2!		O.1%if it	e. Set 3490A RANGE to		100V. Reduceinput to
is a 50 Hz model.			1.00000v.
AC CALIERATOR
h p 7 4 5 4
l 0 D O 0	0 0 0 0 0	ELECTRONIC
i @ @ @ @ @ @		COUNTER		MULTIMETER
		hp 53OO
				h p 3 4 9 O 4
			C H A S S I SG R O U N O	r-------l		U
			CONN€CTEO1O		I	t l r
e	o @		o	Q	+T-F++F
					o o

Figure5-3. AC Common-ModeRejectionTest.

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