I went ahead picked up a WR-50B, and running it through the paces. Putting up on the scope, I'm noticing that the output seems a little bit off. Or is this the low frequency distortion mentioned earlier?
For example, here is what I get when I do a simple sine wave:
Notice how flat the lower cycle is compared to the top. Also, when I do sweep mode, the blanking period is definitely not flat:
And when I plot them both with the second being the output of my homebrew Sencore SG-165 demod probe, I get the following -- note the spike at the beginning of the sweep... related to the above?
I wondering then, if this is an issue of basic calibration or if I should re-cap it first and then try a calibration?
Edit: Both tubes test excellent on my emissions tester. I've also found that different frequencies and different ranges have different levels of distortion, so wondering if it might be a calibration issue then. Also, I've found that if I turn the ON/OFF MOD past about 12:00, the modulation frequency goes down... hmm.