[Boatanchors] Tube Oscillator Circuit Question

[whitebear1122 at comcast.net]

I am working on resolving one of the two remaining issues with my HBR-13 12
tube dual conversion superhet receiver.  The receiver works but the BFO
waveform has bothered me since I built it.  

 

The output of the oscillator is not a nice sine wave as I was expecting.
The photo shows the oscilloscope at the oscillator plate pin 5.  Amplitude
is about 96 volts p-p.  I pulled the tube to measure DC voltage applied to
pin 5 and 6,  151v.  The waveshape on the tuned circuit side pins 1 and 2
looks good, a normal sine wave.  I just don't know what I'm seeing.  Any
advice is appreciated.  Thanks. 73, Scott WA9WFA  

 

https://www.qsl.net/wa9wfa/HBR13_BFO