the (F) suffix for CRTs always indicates a Flat Face. a 5UP1 has a
spherical face, but a 5UP1(F) is flat (these tubes only come from Japan, the US makers did not offer this variation). I have never seen an (S) suffix in real life, maybe someone has added that to distinguish between the flat and spherical versions of the same tube.
the 5DEP1(F) was a very popular CRT for low end scopes, it has very high brightness with low anode voltages, and good deflection sensitivity, coupled with a flat face, and you have the makings of a very nice lower frequency (10-20Mhz) scope.
we do have some if you need one (although not so cheap), see:
they also show up on ebay regularly, as they were used in many 5" low end scopes and kits.
often new tubes from un-built kits show up at a good price.
all the best,
walter
--
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:-
+We're all in one boat, no matter how it looks to you. (WS2)
+All you need is love. (John Lennon)
+But, that doesn't mean other things don't come in handy. (WS2)
+Nature is trying very hard to make us succeed, but nature does not depend on us.
We are not the only experiment. (R. Buckminster Fuller)
