[Amps] SB-220 mod

[kingwood]

Greetings to all,

        I found this HeathKit Service Bulletin.  If this is the bulletin 
Carl mentioned, it does apply to the filament transformer, but has 
absolutely nothing to do with what we were discussing with this thread.


------------------------------------------------------------------------------------------------------------------
                        April 26, 1985
SB-221                                          Bulletin No:
2 KW Linear Amplifier                           SB-221-14

                T2 Overheats And Fails When Operating On 220 Volt Line

When the linear amplifier is wired for 220 volt AC line operation, and
the contacts on SW2 [PN 61-45] or a high voltage transformer winding
opens, excessive current will flow through the primary of low voltage
transformer T2 [PN 54-238],
causing it to fail.  To prevent this failure, the black-green lead and
the black-yellow lead of T2 are lifted and connected together with a wire
nut.

To do this, refer to the drawing at the right and remove the black-green
lead at lug 3 of terminal strip AE [the lead from T2 at grommet AK] and
the black-yellow lead at lug 2 of SW2.  Connect these wires together with
a wire nut [PN 432-199].

Make this wiring change on units you receive for service which are wired
for 220 volt AC operation.  Let the customer know that this wiring change
has been made.  If he wants to operate on 120 volts AC, he'll have to
reconnect these wires as shown in the assembly manual.
-------------------------------------------------------------------------------------------------------------------73 
de Lon, K5JV

1110 Golden Bear Ln.
Kingwood, TX 77339

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