08-28-2013, 06:37 PM
A couple of questions about the mixer tubes in these chasses. I recently acquired a 40-190 code 121, which I haven't started working on yet. The chassis is still in the cabinet. But I noticed that the mixer tube, a 7J7 per the schematic, is a 6J8G, a tall ST style tube with a grid cap.
But in the 40-190 pics posted by 37silverstreak, the mixer is a loctal, presumably a 7J7.
In the 40-180 pics posted by EricS, the mixer appears to be the same ST type as in my 40-190.
I also have a 40-150 with a loctal 7J7 in that position. This is virtually the same chassis as the 40-180, so I would expect the same tube.
Anyone know what gives? Is this just a matter of Philco using up the stock of 6J8 tubes or compensating for a 7J7 shortage? I somehow doubt this was a running design change. It just seems odd that in a small sample we have two of each type of tube.
Splendid restoration, 37silverstreak, by the way.
But in the 40-190 pics posted by 37silverstreak, the mixer is a loctal, presumably a 7J7.
In the 40-180 pics posted by EricS, the mixer appears to be the same ST type as in my 40-190.
I also have a 40-150 with a loctal 7J7 in that position. This is virtually the same chassis as the 40-180, so I would expect the same tube.
Anyone know what gives? Is this just a matter of Philco using up the stock of 6J8 tubes or compensating for a 7J7 shortage? I somehow doubt this was a running design change. It just seems odd that in a small sample we have two of each type of tube.
Splendid restoration, 37silverstreak, by the way.
John Honeycutt
