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Production changes: 16B
#13

Here's an interesting issue:

In checking the LO, I found that even on the lower bands, the output waveform is not good. It's the ugliest cathode follower I've ever seen. Icon_sad

Looking at the actual oscillations at the plate, waveform shape is a nearly perfect sine. However, looking at the cathode follower, it's more like a half wave rectified signal. All but the top 10% or so of the lower half of the waveform is not there. But it's not a clean clip, it's more like a slight upward slant at the bottom of the waveform.

I can't find or figure any reason for this, other than a bad tube. It speaks to inadequate bias, but the voltages are very close to spec. I've replaced the 500 ohm wirewound in the cathode circuit with a 500 ohm flameproof, but no difference. Checking other components in the circuit I found no problems.

All of this, added to the drop off on the lower end of the high bands, I can only think of the tube, but perhaps there's something in what seems to be a very simple circuit that I'm missing.


Messages In This Thread
Production changes: 16B - by BrendaAnnD - 01-08-2013, 09:54 AM
RE: Production changes: 16B - by Ron Ramirez - 01-09-2013, 01:34 PM
RE: Production changes: 16B - by BrendaAnnD - 01-09-2013, 05:28 PM
RE: Production changes: 16B - by Ron Ramirez - 01-09-2013, 07:13 PM
RE: Production changes: 16B - by Chuck Schwark - 01-09-2013, 10:35 PM
RE: Production changes: 16B - by TA Forbes - 01-09-2013, 11:30 PM
RE: Production changes: 16B - by BrendaAnnD - 01-10-2013, 02:02 AM
RE: Production changes: 16B - by TA Forbes - 01-10-2013, 10:12 AM
RE: Production changes: 16B - by Ron Ramirez - 01-10-2013, 10:16 AM
RE: Production changes: 16B - by BrendaAnnD - 01-10-2013, 08:18 PM
RE: Production changes: 16B - by Ron Ramirez - 01-10-2013, 08:31 PM
RE: Production changes: 16B - by BrendaAnnD - 01-10-2013, 08:44 PM
RE: Production changes: 16B - by BrendaAnnD - 01-11-2013, 09:51 AM
RE: Production changes: 16B - by TA Forbes - 01-11-2013, 02:46 PM
RE: Production changes: 16B - by BrendaAnnD - 01-16-2013, 10:02 AM



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