In article ,
"Frank Dresser" wrote:

"David Forsyth" wrote in message
...
So basically if I could somehow use 30's tubes to tune to 100 MHz more
or
less, all I would need to do then is to add a suitable FM detector and
bingo? Hmm I think I will need to do a lot more research on this
one....


Dave



You should be able to get good performance with acorn tubes in the front
end. Acorn tubes pre-date octals, if I recall.

The prewar FM setup not only used a different band, but also a different
audio pre-emphesis. 100us as compared to the current 75us.

Different pre-emphasis is hardly a big deal, the important thing is that
the only significant difference was the frequency band used. The FM
deviation was the same for the pre war and the post war systems, so a pre
war IF strip and detector would work on the post war band, the only
potential problem being image responses due to the lower IF frequency used
pre war.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/