Model 4342A Section III
Paragraphs 3-1 to 3-9
SECTION III
OPERATION
3-1. INTRODUCTION. those in the tuning capacitor, the Q volt-
meter input resistance, output resistance of
3-2. The 4342A Q Meter can measure the the oscillator signal injection circuit, and
quality factor of inductors from 5 to 1000 contact resistances of the measurement termi-
and, in addition, capacitance, inductance and nals. To avoid ambiguity, the Q meter read-
resistance, and the dielectric constant of ing or "circuit Q" is called "indicated Q"
insulating materials over the frequency range throughout the balance of this manual. The
of 22kHz to 70MHz. This section provides the "effective Q", which is dependent only on the
instructions and information necessary for inherent loss of the sample and can be meas-
operating the 4342A Q Meter. ured only by an ideal measuring circuit, is
somewhat greater than the "indicated Q".
Fundamental operating procedures and general However, the "indicated Q" can approximate
techniques for measuring various parameter the "effective Q", by reducing instrument
values of the unknown directly and indirectly losses as much as is possible. So, in most
by using accessories appropriate to the instances, these Q values can be deemed to be
characteristics of the unknown are also the same. The 4342A employs a Constant Volt-
outlined in this section. age Injection System obviating the use of a
thermocouple level meter (the resistance of
thermocouple device would contribute addi-
3-3. PANEL CONTROLS, CONNECTORS AND tional losses to the measuring circuit) and
INDICATORS. the coupling resistor used in traditional Q
3-4. Control panel, top terminal deck, and meters. The low output impedance of the in-
rear panel features of the 4342A are des- jection transformer, the improved operating
cribed in Figures 3-1 and 3-2. The numbers performance of the Q voltmeter, and the pre-
in the illustrations are keyed to the des- cision tuning capacitor which has extremely
criptive items for each figure. Other de- low loss over a wide frequency range minimize
tailed information about the functions of the the difference between the "indicated Q" and
"effective Q".
panel controls and connectors is provided in
paragraphs 3-8 through 3-11.
3-8. GO/NO-GO FUNCTION.
3-5. Q MEASUREMENT-GENERAL.
3-9. The 4342.4 Go/No-Go function provides
an annunciation when the measured Q value ex-
3-6. To complete the measuring circuit, the ceeds a reference value. Two annunciation
Model 4342A requires the connection of an in- outputs, the OVER LIVIT lamp display and a
ductor to the measurement COIL terminals. relay contact output (rear panel) are avail-
This circuit is then used to establish a able. The OVER LIMIT indicator lamp lights
resonance, either by setting the frequency and the relay is energized when the measured
controls to a predetermined frequency and
varying the tuning capacitor, or by preset- Q value is over the reference value set by
ting the tuning capacitor to a desired value the front panel Q LIMIT control. Annuncia-
tion time can be selected to occur at either
and adjusting the frequency controls. Reso- 1 second intervals or to be continuous by the
nance is indicated by maximum deflection of rear panel OVER LIMIT DISPLAY TIME switch,
the panel Q meter. The Q value of the sample When the switch is set to its 1 set position
is proportional to Q meter deflection at the and the Q meter indication goes over the pre-
resonant frequency. set Q limit control value, the OVER LIMIT
3-7. The "indicated Q" which is the Q meter lamp lights once for 1 second. In the con-
reading at resonance is called the "circuit tinous mode, the lamp stays continuously lit
Q" because it includes all the additive during the entire time that the Q value meter
deflection exceeds the preset value. Relay
losses inherent in the instrument including contact output follows in the same manner.
3-l |
ACEC
