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Title: Cathode modulation improvements? Post by: SA2CLC on August 07, 2016, 03:42:57 PM Hello,
Threw together a cathode modulator aka "the simplest modulator" a couple of days ago for my 807 cw transmitter. Sure enough it worked at the first try, but looking at the waveform in the scope, it is very flat topped and comments on the air wants me to "modulate heavier". I see a lot of recommendations about using higher plate voltage than usual. I have 600v on the 807 plate, but I can't really increase the plate voltage on this tx. Will altering the 50ohm cathode resistor on the 6y6 improve this? //Tommy, SA2CLC Title: Re: Cathode modulation improvements? Post by: W7TFO on August 07, 2016, 05:55:12 PM If your mod tube is indeed in series with your final (rather than some other coupling method), you can increase your B+ to full ICAS as there will be a drop of usually 25%-30% across the mod tube.
73DG Title: Re: Cathode modulation improvements? Post by: SA2CLC on August 09, 2016, 02:20:44 AM I Increased the value of the cathode resistor until the carrier was down to about 5w, made it possible to modulate close to 100%. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Should have tried 1200v on the plate of the 807. |