old car radios don't use variable capacitors, they vary L not C



"Bob Miller" wrote in message
...
On Sat, 7 Jan 2006 12:34:21 -0600, "Pete KE9OA"
wrote:

I've got a Sony 6500W radio. Even with the cheapest multi-band radios
there
were separate oscillator and antenna trimmers for each band. Not so with
this radio! Sony chose to use the same pair of rear mounted trimmers for
the
AM and all of the shortwave bands.
What I need to find is a currently available AM only portable radio so I
can
remove the tuning capacitor and mount it inside of the 6500W. The purpose
of
this whole thing is so I can have a separate tuning capacitor for the AM
loopstick.
The fact that this radio uses the same trimmer pair for the SW ranges is
ok,
because since the antenna circuit for these ranges is relatively low Q
tracking error is not a problem. The problem shows up when you are tuning
a
loopstick that has a Q of 400+.
Now, if I can find a nice low-profile cap I will be all set. One other
thing
about this radio............it is dual conversion on the shortwave ranges
but single conversion on the MW band. It isn't a bad MW performer, though.

Pete


I'd look at a car parts junkyard, where you might find an AM-only car
radio for peanuts; or, if you know what you want, just get in touch
with a place like Mouser.com (no minimum $$ on orders), and order the
exact trimmer cap you want.

bob
k5qwg