I recently acquired a nonworking HP-428B. The price was right, free. I
downloaded a 428B manual from BAMA but find that HP introduced modifications
that are not covered in the earlier BAMA manual version. Mine has a serial
number prefix 0995A. It has tubes and discrete transistors mounted on a
printed circuit board, no point to point wiring. One of the tubes is
missing and there is no identification of the tubes on the PC board, no tube
number or V-X reference to a BOM. The socket is for a 9 pin miniature tube
and is located immediately to the center left of the power transformer.
It's not a rectifier as there is a SS diode FWB.
Can some one identify the tube for me and/or suggest where I might be able
to locate a manual that covers my version of the HP 428B?
David
KC2JD
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