[Amps] 4K Ultra Restoration

[Bob Maser]

Well, I found a 4K Ultra, brought it home, and started to clean up the years 
of cigarette tar that this amp had been subjected to.  Not a pretty sight 
but fixable.  My first surprise was finding that some previous owner had 
replaced the original 240VAC blower with a pair of 115VAC muffin fans 
connected in series.  Does anyone out there have a blower that will fit? 
Can someone tell me what was the original blower used in the 4KU?  Looking 
at the Grainger catalog, it looks like the only one they sell that could 
possibly work is the Dayton 4C869, which is 230VAC @ 1600 RPM but I'm not 
sure of the opening size match.

Also, I pulled out the 8877 and I believe it is the original.  It has what I 
think is a date code printed on the top of the anode cap "7707" and I assume 
that this is from the 7th week of 1977.  It may be older than the amp 
because the amp uses a ceramic 2000pf Jennings cap in C2, which I understand 
was glass when the amp was first introduced in 1971 and later on they 
started using the more modern ceramic cap.  My amp does not have a serial 
number label so I don't know how old it really is.  I haven't gotten the RF 
deck off the cabinet yet so I don't know how many surprises are under there. 
The amp was operational when I first saw it about a month ago although it 
took about 100W to get 1500W out of it so I am going to have to replace the 
8877.  Anyone have one for sale at a reasonable price?  Ultimately I am 
planning on installing the new Eimac 3CX1500D7 but for now I just want to 
clean it up let it make RF.

Help is appreciated,
Bob Maser  W6TR
Valrico, FL




Bob