Kenwood KA 9077 Service Manual

Page 2

10

CIRCUIT DESCRIPTION

MC HEAD AMPLIFIER

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E
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x F
E 05 01 9" 015
*' cazooo x
3 8
mean»: x m
8 E ,.
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w 0
=3 3 , *5
.- m
: Er GIBI
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Fig. 1 MC Hlld Amplifier

The MC head amphher consusls of a Imeerslage, svmmemca
complememary clrceu. usmg low»no4se lrsnsismrs in the IHSI
slag:

An emmer IoHower circuit IS used m the final sIage so mat
the common emmer mmm m vhe second stage was
sulhcuem amulmer

Negatlve Ieeubauk hum me nnal slage emiuar .5 applied In
Khe Ivrsl sxage emnter, and the addmonal DC negaIlVE
feedback irom [he second SlagE emmer IS apphedm the IIISI
stage base which makes onevanon very 51am

The advamagos of mo complememary nlrcmt are'

1 AHhough Iransxswrs'OW and 03 05 and O7, and 09
and (111 are dlleCIW connecxea m serves, mesa causal
vansxsmrs can conduct as a DaraHed cxrcun Ior (he
outpu: and Input svgnals Consequently (he oulpm
Impedance can be lowered and a mgher ouxpu: voIlage
can be ubvamed

Z Push-pull opevauon reduces We dlswman

3 The cerUlI convuguuauon makes me best use of ma hxgh
S/N characlellsucs oI me vansusmrs.

POWER SAFETY INDICATOR cmcun
-_"_°£22°_'2E _______

To 02-: Lulluum

2 Powcr "fay indie-tor circuit

The LED meke-s Iuv ubuul ten seconds aner power-on and
becomes COHSIH'II by the molecnon reiav being energized
when all mean; In me KAVQO7 are mamlned an mam;
mumvmramr IS used to maker me LED

VGC

l

Fig. 3 Mable Multivibrahor

The Lambs muluwbramr comm: of two same Iran-aimed.
021 am: 022 Smelly. charactensncs u! transmora are
dufferem

When me CIICUIL I5 energized, GZI and 022. both DI the co"
lecvor curvsms flow

The conccmr currem DI euher cI two l5 \argerthen the mhar
because 04 hFE dsflerencs or the We

Assume. me coIlacwr quflem of Oil 5 large! than that CI
022