Bob,
The article details a modification to allow higher gain and better
selectivity (as realized in the 250C) by modifying the 250 to conform to the
250C performance. The circuit changes are easy and amount to only a few
components (or so the update states). I will send you a copy of the article
w/schematic as an e-mail attachment, if you desire. The article does not
discuss the tube change you mentioned.
Roger Brown, KL7Q

Bob Balonis wrote in message
ink.net...
Does anyone have access to a Ham Radio Magazine Dec 1969 article regarding
a
Swan 250 modification (page 84). If so could I either get a copy or info
on
what this mod is? Working on a Swan 500CX whose manual has a note that
this
modification was made - there has been a modification to use alternate 1st
and 2nd IF tubes, 6GM6s versus the stock 12BA6s - is this the mod
discussed
on this article?

Many thanks, Bob NB3W