Heathkit HW-12 - Page 39

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HHATHEKIT
Figure 3
The following modifications must be made to
permit the Transceiver FUNCTION switch to
turn the Power Supply On and Off, This modifi-
cation does not alter the Power Sunnly circuit
ARIS ES LOL AMES Ie OWS CSUppsy CiPCult
for use with other equipment, Refer to Figure 3,
1. Remove the Power Supply bottom plate,
NOTE: It may be easier to make the following
wiring changes if the heat sink closest to the fuse-
holder is removed, Mark the lead colors on the
heat sink next to the terminals from which the
leads are disconnected, so they can be recon-
nected properly, Be careful not to lose any of
the insulating washers,
2, Remove the wire connected between lug 4
of the relay and solder lug X.
fou)
Connect a length of #18 hookup wire from
lug 4 of the relay (S-1) to lug 5 of socket
§ (S-1).
4, Connect a flexible wire from the armature
of the relay (S-1) to solder lug X (S-3), This
wire must be flexible enough to permit
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proper operation of the relay, yet be heavy
enough to carry the necessary current, A
length of braid from a piece of shielded
cable, with sleeving on it, should be satis-
factory
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Position this wire away from the
other wires to permit free operation of the
5. Replace the heat sink (if it was removed)
and be sure to replace the imsulating
washers properly, Reconnect the heat sink
leads,
6. Replace the bottom plate,
7, Because the filament current now flows
through the Power Supply fuse, it should
be replaced with one rated at 20 amperes,
NOTE: The HP-10 and HP-20 power cables are
electrically quite different from each other, and
if they are interchanged, the Transceiver will
not operate properly. It is suggested these
cables be marked for easy identification,