[Heathkit] SB 220 transformer substitution

John King k5pgw at yahoo.com
Mon Dec 21 08:23:54 EST 2009


The power transformer went bad in my SB 220 that I have now owned since new and is now 35 years old. Been a GREAT amplifier!!

I
have an outboard Drake L4B power transformer on it that I put on it
about 10 years ago.  The way the outboard transformer is connected only
gives me 1900 volts in the SSB position. If I remember correctly, I
just taped up the leads from the CW/tune switch and did not connect
them to the L4B transformer.

Since my L4B has a CW/tune switch
and a SSB switch, I  would like to use the SB 220 that way and get 2700
vdc on SSB and the 1900 vdc on CW/tune. The schematic of the Drake L4B
isn't clear to me what transformer connections would provide both
voltages to the SB 220. Has anyone on the list done this outboard
transformer swap? If so, can you tell me the manner in which you
connected to get the two voltages? The benefit of your experience and
knowledge will be greatly appreciated. Thanks and 73, John, K5PGW


      


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