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8/14/1999 3:59 PM
Just picked up a Harmony H430 amp, two 10" jensens  
and reasonable iron. Looks like it is worth restoring.  
The amp uses three 6973 tubes which are a bit  
pricey. I looked through the chart of a drug store  
tube testers with a bunches of test sockets, and  
found the base diagram for the 6973. I then found that  
the 6CZ5 had the same base diagram. Who says tube  
testers are worthless? I had serviced a bogen PA head  
a few years ago that used two 6CZ5 for output tubes.  
The 6CZ5 seems like a possible substitution.  
My RC-25 RCA tube manual specs suggests the two tubes are  
extremely similar but 6CZ5 is not listed as a substitute  
for the 6973. 6CZ5s can be purchase for $6 while the  
6973s are $25+. Two of the 6973 are the output tubes and the other one I am not sure about. I suspect it drives the reverb. I have not pulled the chassis and do not have a schematic handy.  
Any second opinions?

Graywater Rob,Yer real close ... -- 8/14/1999 8:20 PM
Bruce Yes, the odd 6973 is the reverb dri... -- 8/15/1999 4:54 AM