[Boatanchors] RBM LF Receiver schematic or manual?

[Ian Wilson]

The RBM-4 MF receiver is alive and receiving, with the aid of the schematic
(from various people - thank you all) and with the RBS manual (for component
values).

The previous owner had replaced the original tubes with 6.3v types. I don't
know
what audio o/p tube was used to replace the original 12A6. Whatever it was
didn't test well so I installed a 6K6. One of the 6SK7's was dead.

The audio chain didn't work; turned out to be an o/c 430k(!) screen dropper
resistor. The associated bathtub cap seems fine. Once I replaced the
resistor
the RX started pulling lots of BC AM with a couple of feet of wire
"antenna".

Some year I might get around to reversing the front panel mod the previous
owner
made (toggle switch in place of antenna connector) and do something about
the output stage (someone installed a small o/p transformer but didn't do
anything
else to the o/p stage, so it produces some rather nasty audio output).

If anyone collects these I'd be happy to trade you something for it. The
front
panel condition is fair.

73, ian K3IMW