05-28-2018, 07:09 PM
Curious how your testing the Mallory 150 caps for leakage ?? Usually for coupling caps you check the insulation resistance ....
You should be fine with the 30-30-40-40 cap can... you can double up if need be on the screen voltage if you want the amp a bit tighter...
As for RF...most likely a early stage making for rectification of the AM... First start out with placing resistors in the grids of the small tubes... since your in affect making a 1st order POLE with the input miller capacitance of the valve.. Keep in mind 540kHz is lowest AM band.... so you have plenty of room to filter without monkeying up the audio band.. common to use 68K into 12AX7 tubes...
You should be fine with the 30-30-40-40 cap can... you can double up if need be on the screen voltage if you want the amp a bit tighter...
As for RF...most likely a early stage making for rectification of the AM... First start out with placing resistors in the grids of the small tubes... since your in affect making a 1st order POLE with the input miller capacitance of the valve.. Keep in mind 540kHz is lowest AM band.... so you have plenty of room to filter without monkeying up the audio band.. common to use 68K into 12AX7 tubes...