08-05-2012, 11:57 AM
Are there any documents available that describe the theory of operation of the audio section on the 38-690?
I have one on the bench, with one issue remaining, no appreciable voltage level out of the tweeter transformer winding. Tuning a local station and adjusting the volume for annoyingly loud output I still only measure 500mv to 800mv p-p output.
I've injected audio into the 6R7 grid at various frequencies and have good levels on the 6L6 grids, but still only millivolts on the tweeter winding.
I did find that the "whistle" filter now has the notch at 10.8KHz
Any help appreciated.
Chuck
I have one on the bench, with one issue remaining, no appreciable voltage level out of the tweeter transformer winding. Tuning a local station and adjusting the volume for annoyingly loud output I still only measure 500mv to 800mv p-p output.
I've injected audio into the 6R7 grid at various frequencies and have good levels on the 6L6 grids, but still only millivolts on the tweeter winding.
I did find that the "whistle" filter now has the notch at 10.8KHz
Any help appreciated.
Chuck
