Description - BRUEL & KJAER 1022 Instructions And Applications

Description
General.
The Beat Frequency Oscillator Type 1022 is primarily designed for electrical
and electro-acoustical measurements.
It
works on the heterodyne principle using two bigh frequency oscillators,
o 'ch o erates on a fixed frequenc while the f uency of the other
can be altered b a variable ca acitor, The required audio frequency
IS
en
obtained as the difference between the hvo
~igh
frequencies and can
~~_!_~:ld
off a large illuminated
~c- ~ ~~~th~p~i nter ~f-whichTs-c-~-~~~de(Ct~-th- ;-vari_ ~ Qle
~capa:!~Jjie:OS.ci~1s lo~arit~ ~g~aduated
from 20 to 20oo;;-· c/ s. An
INCREMENTAL SCALE is also provided, allowing exact frequency selection
~ in the range
- 50 to +50 c/ s around any setting on the main scale.
The zero-adjustment is controlled by
-~~~ inin [3_~- ~ .ll_Ll) _Ert_w_e_en_jh.e.-f.l:eq-t!.mG-y
'of the __ !fiains voltage, and that
of -th~--<>.~<:?i!!~!9_~ volta~e
. occuring
w~ ~- ~
__ the
--~~ii-la!Qr._i;_i;med .to ±hilr~q~-~~~y-~f
the mains
;~d--th~--:p-ress~~tton - ~arked
PoWER FREQUEN
cv
BEA-T
~~~_i!l_t:
__
frunLl>_aneL;;Ti~~ii~"}~- presse~.
The variable capacitor has two control knobs, one of which is in a fixed
position on the capacitor spindle and is used for quick setting to the de-
sired freguency . . The other will , when depressed, rotate the spindle \vith a
_r.a_tio of 1, to 5 giving greater accuracy and fine selection of the frequency.
A worm gear permits the
~:l__Eac itor
to be tuned
automa~.!~-~!!L_Jor
example,
with the aid of the motor of the Level Recorder Type 2305. The mechanical
connect:rorl-To-Tl1e--Levcl ___ Re-corder -is effected by means of a
fl ~~~ haft
.
'-------------·-··-
···-·-
·-···
-
------
.. ·-··· .. ···- .
•
..
'
.
. . .,
which can be screwed onto the bushing on the side of the Oscillator's cabinet.
The -
worm
g;;~~
-
~~-;_:;- b-e--enga:gea-·a nd
rele{\-sed--w1ill11ie -aTCi ___
of' _ a .
buil't-=- i ;
electromagnetic clutch, operated from a switch on the front panel marked
AUTOMATIC SCANNING, or by a remote control arrangement. The electro-
- m agnetic clutch is a friction-device allowing manual tuning of the variable
capacitor even when the clutch is engaged.
Being also designed for use in room-acoustical measurements, the Beat Fre-
quency Oscillator is equipped with frequency modulation, for which a re-
actance tube controlled by saw-tooth oscillations from a built-in oscillator is
switched into the circuit of the fixed oscillator. Both the frequency and the
amp-litude of the saw-tooth oscillation are adjustable and may be read off
two printed dials. Provision is also made for external modulation, whereby
very wide limits of frequency modulation can be obtained.
By means of a comp.!_essor circuit,
which~
can be controlled from an
~
~~t~ge,
it is possible
t~voltage,
current, or sound pre- s sure constant
during measurements when using the oscillator as a power source.
5