Phil Your unit is built to schematic 27500, and should have 6EJ7, 6BA6, and 6BZ6. Earlier units (27000) had the 12V tubes.
73, Garey - K4OAH Walker wrote:
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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