I've just bought a Heathkit SB-200. Superficial inspections looks good; no
sign of burned contacts, corrosion, etc. Transformers appear fine.
There do not appear to be any Harbach board modifications made. I will need to
install the softkey before I can use the amp, and I am planning to put in the
soft-start at the same time.
There is one connection that I cannot reconcile with the manual, but I am no
expert on this amp. See the photo below:
https://s3.amazonaws.com/files.qrz.com/r/n5wvr/SB_200_plate_wiring.jpg
The plate connections of the two tubes run through a capacitor/inductor circuit
to a green RF choke. There is a short uninsulated wire that runs from this
choke to a lug, and it appears that it once connected to a screw terminal on
the capacitor bank wall. However, it is hanging loose.
There is also a capacitor of about 5800 pf running from the end of the green RF
choke to a grounded lug on the sheet metal panel above the capacitor bank. I
am not seeing this in the manual at all.
Is there a known SB-220 mod where this direct connection is replaced by a
capacitor? What purpose does it serve?
73,
Cathy
N5WVR
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