My 42-380 floor model Philco Has a 7A4 tube in place of one of the XXL tubes as called for in the schematic. It reads good on my tube tester but is it a proper replacement for the XXL or should I get another XXL ?
Thank You
Hi,
The 7A4 is a direct substitute for the XXL and should work fine. If you look up the XXL on tube suppliers websites they usually show XXL/7A4. Have several 7A4's in radios that work fine in place of the original XXL Philco tubes. John
Agreed. Some of these are microphonic, Just like the 6C5/6J5 that are the of the same family, sort of, but as an oscillater or IF amp, it shouldn't matter too much. Anyway no harm in trying. Switch 'em around for best performance.