Hi Ed:
The Swan Mk II came without a tuned input. Most amplifier are difficult to
retrofitl a tuned input - but the Mk II is one of the few that is rather
easy.
The bandswitch shaft is a standard shaft and the spacing is also standard.
I found an old ceramic receiving type wafer that was 5 position single
throw. Install it just behind the front panel and run the wires from each
position below deck to a bank of 5 dpdt miniature relays. Mine were 28 vdc
type. There is room under deck to install the 5 relays and a small board
containing toroids and capacitors for each band. Then, run coax to and from
the relay board.
One of the Radio Handbooks has the data for the input circuit. Any of the
amps using 2 x 3-500 tubes will work fine.
Mine works fine. It is more ruggedly build than the Heath and coasts at
1200 watts output. I can get more out, but 1200 watts seems to be where it
wants to run very nicely.
While I had the amp apart, I shielded the meter. Originally, it had no
shielding. I also added a driver transistor to reduce the relay current
switched by the transceiver.
73, Colin K7FM
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