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4-51 MAXIMUM OUTPUT VOLTAGE
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Maximum output voltage to a 600 ohm resistive load
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should be at least 3 volts at all frequencies.
I 5.5 mhy
If output is low, increase high frequency oscillator I
I output and balance oscillator output levels. See high
47 uuf
frequency oscillator adjustment procedure given in
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test procedure section.
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7-45 uuf 4-6 COMPLETE TEST PROCEDURE
I 'U The procedure that follows is suitable for all -hp-
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Model 650A Test Oscillators. Modernization, par-
ticularly those instruments with serial numbers below
2500, is recommended prior to undertaking this Com-
plete Test Procedure.
f 2 % f 2 % 1
10,000 n The following test equipment will be required:
a. An ac vacuum tube voltmeter with known frequency
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response from 10 cps to 10 MC. -hp- Models 410A
25,000 n and 410B are suitable for this purpose.
BALANCE
4 CONTROL b. A distortion analyzer such as -hp- Model 330B.
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c. A means of constant line voltage control from 100
to 130 volts.
1
Figure 4-2. 100 KC Filter d. A dc voltmeter for setting 180 volt output from
regulated supply.
When using only a vacuum tube voltmeter, connect a
resistive load of 600 ohms across output terminals. e. Frequency determining equipment covering 10 cps
Check at 1 KC and at 2 MC if a 400C is used and also to 10 MC range. An oscilloscope and frequency 1
at 4 MC if a 400D or 400H voltmeter is used. standard such as -hp- Model 100A, B, C, or D would
be suitable for frequencies up to 100 KC. A crystal
4-5G CHECK FOR 60 CPS BEAT calibrator could then be used over the 100 KC to 10
1
MC range. A single electronic frequency counter such
as -hp- Model 524A or 524B could also be used to
Tune to approximately 55 cps and adjust AMPLITUDE
determine frequency over the 10 cps to 10 MC range
control for an approximate indication of 0.9 full scale in place of the above equipment.
on output meter, Slowly tune up through 60 cps and I
note amount of greatest meter swing. The total max- f. An oscilloscope such as -hp- Model 130A or 150A.
imum swing should not exceed 4% of the full scale
value. See paragraph 4-7, Trouble Shooting. I
g. Elimination filter for 100 KC as shown in Figure I
4-2. Any coil and capacitor combination can be
4-5H INSTRUMENT RESPONSE TO used that will resonate at 100 KC. If a different in-
LINE VOLTAGE CHANGES ductor is used, the value of the balance control and
series resistor will have to be changed. The inductor
Set output voltage at 10 cps to a reference level on shown in Figure 4-2 can be obtained under -hp- Stock 1
650A output meter. Vary line voltage from 105 to 125 NO. 48-3.
volts. The output meter indication should not change
more than 2% of full scale. If out of specifications, Refer to Figures 4-9 and 4-10 for circuit references
repeat check using an external voltmeter to determine unless otherwise designated. All ac or dc voltages I
if poor response is caused by the amplifier or the out- are measured between the indicated point and chassis
put meter circuit.
ground.
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4-51 OUTPUT IMPEDANCE - NOTE -
Set output attenuator to the 3 volt or +10 db range and The "R.M.S. VOLTS/DB" output attenuator
tune instrument to approximately 1000 cps. Adjust switch must always be in the "+lo - 3.0" po-
AMPLITUDE control to obtain a full scale (3 volt) sition unless otherwise instructed. I
output meter indication with no load connected to output
terminals. The meter indication should drop to half
A complete test requires completion of all of the fol-
scale (1.5 volts) when a 600 ohm resistive load is con- lowing tests in the order given. In some cases where 1
nected to the output terminals. only partial testing is required, some steps can be
-18-
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ACEC
