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6973=6CZ5?

8/14/1999 3:59 PM
Rob	6973=6CZ5? 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?

8/14/1999 3:59 PM

Rob

6973=6CZ5?

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?

Replies:

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