Cj Premier 11A fuse

Since no one has responded I'll hazard a guess. My Premier 12's use KTK-1 by Limitron. Since the circuits are similar good chance your 11's use the same.

Those fuses are not cheap. Most C/J products use the large KTK fuse. I suggest you call them back and ask for Ed. Tell them you never received a return phone call. They should be able to help you. If the fuse is blowing your amp needs service.

I know this is an old thread but here is my 2c.

KTK-1 for later production
BBS-1 for earlier production
KTK is 1/8" longer than the BBS, other than that they are the same.

The fuse will blow if a tube blows. That is what its for.
Voltage spikes and such can also take one out.

Your amp may need service if it is blowing them for no reason. I, myself, have only ever replaced a fuse after loosing a tube.