Operating Modes Of The Y Amplifier - Hameg HM 604 Manual

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defined area of influence on the waveform shape (see Fig.),

offering the added advantage of being able to 'straighten

out' waveform aberrations near the leading edge.

Adjustment points of the probes

alters the middle frequencies

alters the leading edge

T,:

alters the lower frequencies

After completion of the HF-adjustment, the signal

amplitude displayed on the CRT screen should have the

same value as during the 1 kHz adjustment.

Probes other than those mentioned above, normally have a

larger tip diameter and may not fit into the calibrator out-

puts Whilst it is not difficult for an experienced operator to

build a suitable adapter, it should be pointed out that most

of these probes have a slower risetime with the effect that

the total bandwidth of scope together with probe may fall

far below that of the HM604. Furthermore, the HF-adjust-

ment feature is nearly always missing so that waveform dis-

tortion can not be entirely excluded.

incorrect

Adjustment

1 MHz

Subject to change without notice

HZ52

incorrect

correct

The adjustment sequence must be followed in the order

described, i.e. first at

frequencies should not be used for timebase calibrations.

The pulse duty cycle deviates from 1 : 1 ratio.

Prerequisites for precise and easy probe adjustments, as

well as checks of deflection coefficients, are straight hori-

zontal pulse tops, calibrated pulse amplitude, and zero-

CAL.

potential at the pulse base. Frequency and duty cycle are

relatively uncritical.

response,

fast pulse risetimes and low-impedance

generator outputs are of particular importance.

Providing these essential features, as well as switch-select-

able output-frequencies, the calibrator of the HM 604 can,

under certain conditions, replace expensive squarewave

generators when testing or compensating wideband-

attenuators or -amplifiers. In such a case, the input of an

appropriate circuit will be connected to one of the CAL.-out-

puts via a suitable probe.

The voltage provided at a high-impedance input (I MSJ II 15-

1 =

(10:

Suitable probes are HZ51, 52, 53, and 54.

For low-impedance inputs (e.g. 50 Q), a 1: 1 probe can be

employed which, however, must be fully terminated with a

and HZ54. The latter must be switched to the 1: 1 position,

and the HF-trimmer in the connecting box turned fullycoun-

terclockwise.

When connected to the

HZ50, this arrangement will provide approx. 40mV,, at

The voltages given here will have larger tolerances than 1 %

since operation of a 1: 1 probe together with a 5OQ load is

very uncommon.

Using the 2V CAL. socket under similar conditions is only

possible with the HZ54 probe. The potential obtained at the

twice the risetime. Accurate readings of the available input

voltage can be shown directly on the HM604 when con-

necting a 5OQ through-termination between the BNC plug

of the probe and the input of the oscilloscope.