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I have a TR-4, 1968 manufacture date, serial number
28124. It has worked well for years, with the last few being dormant as
my vertical took a hit a few winters ago with icing. I've replaced the
vertical, and I'm trying to re-tube the unit. Here is where the
confusion arises:
The chassis
lettering and schematic for tubes V4, V5, V11 and both agree and are
respectively: 6EJ7, 6BA6, 6BZ6.
Note: the
schematic has V5 and V11 with a hand lettered "6" in front of 6BA6 and
6BZ6 versus all other tubes which have stencil guided lettering.
The
Manual's Voltage Reference chart and Tube List for V4, V5 and V11 are:
6EJ7, 12BA6, 12BZ6
The
Manual's Block Diagram shows V4 as 6HS6
I'm not
sure what's supposed to be right, though I have a tendency to believe
the chassis lettering and schematic. The manual is internally
inconsistent, and doesn't agree with the physical hardware or
schematic. I probably can take out V5 and V11 and measure the filament
voltage present to see if it really is set up for a 6 or 12 volt tube
in those sockets.
I found
some correspondence between the original owner, whom I purchased the
unit from, and the factory regarding a technical problem. The factory
rep wasn't sure in solving a problem whether the former owner needed a
6BZ6 or a 12BZ6 so he sent him one of each. Apparently the factory
didn't know either!
Was there
some changeover for different serial number ranges, between various
tube types or what, and what is the best way to tell which tubes really
belong in the circuits?
Thanks for
pointing me toward a resource, if you know one, to help get some
answers.
Phil WA2CLX
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