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95307-000-01 6/87
RET-041 Instructions
page 3
by the average consumer now limited by the receiver to 3kHz, typically) will be dramatically
improved. On much mass-market equipment, it will be difficult to tell AM from FM.
The radio manufacturers participating in the NRSC stated emphatically that reduction in
interference must be demonstrated by broadcasters before receiver manufacturers would be
willing to release true wideband 10kHz audio bandwidth) receivers to the mass market This
is rational — the receiver manufacturers can lose millions of dollars if they produce receivers
that are rejected as noisy or interference-prone by consumers. In contrast, broadcasters can
easily change pre-emphasis and filtering with very little expense.
Therefore, al±ough this standard is voluntary, we strongly recommend conformance to it.
We are convinced that use of this more modest pre-emphasis and sharp 10kHz filtering
by broadcasters is the only factor that will eventually induce the receiver manufacturers to
build and mass-market the high-fidelity, wideband radios which would allow AM stations to
compete with FM in audio quality. The commitment to do so was strongly expressed by the
receiver manufacturers involved in the NRSC ' s deliberations.
nstallation
* Allow about 30 minutes for this retrofit If installation of Retrofit Kit RET-033 will be
required as it may for units with serial numbers below 700000), allow a total of up to FA
hours.
1) Open the front panel of the 100A/1, remove the subpanel.
It is not necessary to remove the unit from the rack unless Retrofit Kit RET-033 must be
installed — see step 4). The 9100A/1 must, however, be off the air during this procedure.
a) Remove the three hex-socket screws at the top of the front panel with a %4-inch hex
wrench provided with the unit), then tilt the hinged front panel downward to reveal
the interior.
b) Set the AC POWER switch to OFF.
c) Loosen the four DZUS fasteners on the subpanel by turning each %-tum counterclock
wise with a long 3 /i6-inch or *A-inch flat-blade screwdriver.
d) Taking care not to stress the flat cables beneath it, tilt the top of the subpanel outward
and to the left to clear the upper chassis lip and the door support rail at the right
2) Reposition jumpers on Card #7.
a) Remove Card #7 from its slot.
b) Place jumper A on Card #7 in the " CARD 1 INSTALLED " position see Fig. 1).
c) Return Card #7 to its slot.
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