Instructions For Replacing The 2 Cc Coupler With The 6 Cc Couplers - BRUEL & KJAER 4212 Instructions And Applications

3. The two side-boxes on top of the Test box can now be removed.
4. Unscrew the bottom plates B of the side boxes and fill up with sand.
Note: To make the sand settle, it is recommended to stir it while filling.
Side boxes
'0
~
~~~~~ ~
"'
~~------------ ~
Ql
~~~~~------ ~
~~~~~~~~~-----t------ ~
Fig. 8. Exploded view of the Test Box Type 4212.
Instructions for Replacing the
2
cc Coupler with the
6
cc Couplers:
ASA Type 1, Z 24.9/1949; NBS 9A
=
ASA Z 24.5/1951.
The standardized 2 cc coupler included in the artificial ear of the Hearing
Aid Test Box Type 4212 is readily replaced by the following couplers:
DB 0161 which includes the 6 cc ASA coupler Type 1 (Z 24.9/1949), and
DB 0160 which includes the 6 cc NBS 9A coupler. This coupler is similar to the
6 cc ASA coupler described in the standard ASA Z 24.5/1951 Fig. 1.
Both DB 0160 and DB 0161 consist of the 6 cc coupler itself, a microphone
ring, a stop collar, and a packing washer made of insulation material.
To mount the couplers, the artificial ear is pulled out of the Test Box and the
Microphone Cartridge screwed off the Cathode Follower. The stop collar is
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