SB-610

[Peter A Markavage]

The input and output tuned circuits for the vertical amplifier are
nothing more than standard LC circuits. Check the ARRL Handbook or other
reference books on how to compute either L or C. You know the frequency,
pick an "L" and find "C" or vice versa. Using a dip meter or a scope can
help speed up determining the values. Use a tunable L and a fixed C, as
Heath does, or use a fixed L and a tunable C. Years ago I modified my
SB-610 for 3395 KHz IF. Found a tunable inductor(didn't know its value)
from an old TV set; put 100 pf across it and measured where the inductor
resonated. Then played with the capacitor values until I got to the range
I needed. The circuit isn't that critical. You can also add a second
stage to the vertical amplifier to increase the gain to drive the
vertical plates at this frequency but that requires more effort and room.
Pete

>
> Btw, speaking of the 610... is there a source for the "optional"
> IF transformers?  Mine is wired for RTTY and I'd like to convert it
> so I can monitor my FT-101 IF.  From looking at the schematic its
> just a few parts, but there is a couple "medium" transformers...
> L1 and L2 that I need.  I need the transformers for the 3000kc to
> 6000kc vertical input.  Any ideas?
>
>

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