GENERAL RADIO COMPANY 874-GAL Operating Instructions Manual Download Page 6

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874 G-lO

(I)

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0.05

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0.04

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0.03

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Actual AttenuatIon

K) a Indicated AttenuatIon

1000

2000

3000

4000

FREQUENCY,

MHz

Figure 3.

Frequency Correction Factor.

Figure 4.

VSWR seen looking

back into output con-

nector of a typical

Type 874-GAL Ad.

justable Attenuator.

FREQUENCY.

GHz

874 G.8

GENERAL RADIO

Summary of Contents for 874-GAL

Page 1: ...cations the maximum usable attenuation is limited by leakage from various parts of the driving circuit and not by the range of the atten uator In this type of variable attenuator as the attenuation is varied the phase at the output connection is essentially constant with respect to the input signal phase The method of coupling to the coaxial line permits the attenuator to be used as a standard cal...

Page 2: ...ase the special correction given in Fig ure 2 is required and in addition the frequency correction of Figure 3 is required In the second configuration recommended to achieve the best accuracy above 2 GHz the termination is an adjustable stub employed to place a voltage minimum at the coupling points The frequency correction graph of Figure 3 is required only in this case The detailed procedure is ...

Page 3: ...attenuation is accurate at scale readings as low as 9 dB and at frequencies between 1500 and 4000 MHz readings above 0 dB on the calibrated scale are accurate if the stub is set as previously outlined An alternate method of setting a voltage minimum at the coupling point f or frequencies above 1500MHz utilizes the fact that the attenuation constant for the desired mode is smaller than that of the ...

Page 4: ...loss in the line 2 The attenuator can also be used to measure the attenuation of a network by the substitution method as indicated by the block diagram in Figure 6 Readings of the detector output and attenuator setting are first made without the circuit under test connected The circuit is then inserted and the Type 874 GAL Adjustable Attenuator is readjusted to give the same detector indication Th...

Page 5: ... H TYPE 874 GAL L H t j i1Jl J111 L When source Is connected to end of at tenuator marked S subtract correction labeled NORMAL from reading For t opposite connection add REVERSED a correction ft it t 1I I II II 10 0 0 20 30 40 ATTENUATOR READING A dB 50 60 874 0 12 Figure 2 Correction chart for use with Type 874 GAL Adjustable Attenuator when exciting line is terminated in its characteristic imped...

Page 6: ...005 0 00 Actual AttenuatIon 1 K a Indicated AttenuatIon 1000 2000 3000 4000 FREQUENCY MHz Figure 3 Frequency Correction Factor Figure 4 VSWR seen looking back into output con nector of a typical Type 874 GAL Ad justable Attenuator FREQUENCY GHz 874 G 8 6 GENERAL RADIO ...

Page 7: ...e attenuation of a network TYPE 874 R22LA PATCH CORD 1209 5 Figure 5 Block diagram of a simple signal generator using the adjustable attenuator and other GR874 Coaxial Elements TYPE 874 D2OL OR D5OL 874 G 14A TEST TYPE 874 GAL ADJUSTABLE ATTENUATOR 7 ...

Page 8: ...or to end of output cable at 1 GHz when signal source impedance is 50 0 With input line terminated in 50 0 and scale set at 0 dB 30 4 dB 2dB set at 9 dB 17 2dB settings below 0 are not accurate With input line terminated in adjustable stub Which ex tends the range over which the calibration is accurate to the 9 dB scale setting 19 2dB minimum Insertion loss is approximately inversely proportional ...

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GENERAL RADIO COMPANY 874-GAL, Operating Instructions Manual

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