[R-390] Blown B+ Fuse - Cont'd

[Barry]

Last night, I finally got around to doing some testing.  Hooking up a couple
of meters in series (to ensure I was getting readings that agreed since
neither meter is calibrated) where the 1/8A fuse goes, I observed that the
system draws anywhere from 70mA to almost 100mA depending on what's going on
at the time (both meters agreed within 5mA).  AGC with BFO off gave the
least amount of reading whereas MGC gave the most (makes sense).  Also
switching from SLOW, to MED (or FAST) AGC when the 2uF cap dumps its charge
causes the circuit to draw considerably less current until the cap
discharges.  Again, makes sense.

What I can't figure out is why a 1/8A fuse would have blown under these
conditions.  A fast-acting fuse might have sensed a very sudden surge that
these meters would not have shown, but these are slow-acting fuses.

Has anyone done any tests to see how much current the typical B+ fuse is
carrying?  As I mentioned, one of the filter cans is getting just a bit
warmer than the other one so it could be drawing a bit more than normal.  I
plan to replace these with modern equivalents and see what effect it has on
the current situation (no pun intended), but I was wondering if anyone else
has experimented here.

Thanks!

Barry - N4BUQ