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Author Topic: 6T9 AM transmitter problem  (Read 521 times)
N6AF
Member

Posts: 54




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« on: October 11, 2017, 06:44:20 AM »

This question is directed to anyone familiar with the 6T9 based transmitter featured in the 1970 ARRL handbook. The audio waveform at pin 2 of V3A looks great until I connect it with a known good coupling cap  to pin 8 of V3B.  When connected to pin 8 the waveform at that node becomes horribly distorted and non-symmetrical. Pin 8 is a grid so I cannot fathom how this could be loading the plate output from V3A pin 2. I checked the input impedance and it's simply the grid leak resistor value. Changing V3 tube didn't help. V3B bias is sitting nicely at about -8 volts.  Anyone seen this? I hate it when I run into a bug like this but eventually I'll get it corrected with your help. Thanks! 73 N6AF Chuck
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WA2ISE
Member

Posts: 1038




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« Reply #1 on: October 12, 2017, 12:06:09 PM »

How big is your input waveform?  Maybe you're driving the grid positive for part of the waveform, which will cause distortion.  The positive grid will act like a diode. 
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