01-03-2017, 10:03 AM
This is the console version with the 6 tube chassis that I purchased at an auction.
While working on the recapping etc. and getting the radio to working condition, I noticed a couple of issues and wondered if anyone else has experienced these?
* The chassis was very sensitive to any tapping with an insulated tool to any part of it. Sounded like it would go into oscillation and loudness varied with the volume control. So one by one I pulled a tube starting at the front end and working towards the 42 output tube. When I pulled the 75 first audio tube the problem stopped. I replaced the 75 tube with an NOS and the problem is fixed! Are these old 75 tubes known to cause this oscillation problem?
* Next question is normally does the glass 6A7 Oscillator tube need a shield? My chassis does not have a shield or bracket on the tube socket for one. Should I be using a metal tube here? The chassis drawing seems to show a shield.
Thanks
G.
While working on the recapping etc. and getting the radio to working condition, I noticed a couple of issues and wondered if anyone else has experienced these?
* The chassis was very sensitive to any tapping with an insulated tool to any part of it. Sounded like it would go into oscillation and loudness varied with the volume control. So one by one I pulled a tube starting at the front end and working towards the 42 output tube. When I pulled the 75 first audio tube the problem stopped. I replaced the 75 tube with an NOS and the problem is fixed! Are these old 75 tubes known to cause this oscillation problem?
* Next question is normally does the glass 6A7 Oscillator tube need a shield? My chassis does not have a shield or bracket on the tube socket for one. Should I be using a metal tube here? The chassis drawing seems to show a shield.
Thanks
G.
