Putting the blocking/coupling capacitor in the ground leg of the modulation XFMR keeps DC current from flowing through the secondary and leaves the HV on the secondary so that the potential difference from primary to secondary is the closer to the same voltage there by lessening the possibility for arcing between the windings. There is no difference otherwise in the operation parameters of either circuit.
While on the subject, in the circuit where there is no ground connection, the audio return path is through the power supply filter capacitor. This is effectively reducing the amount of capacitance since the coupling capacitor and the power supply filter capacitor are now in series with the audio path. This is OK if the power supply filter has enough capacitance. It even has one advantage, the need for a very HV capacitor as a coupler is reduced to the DC voltage drop across the modulation reactor. In the circuit of Don and mine where the audio path is to ground, there is a slight reduction in hum from the power supply as well. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Geoff/W5OMR Sent: Sunday, November 23, 2003 4:52 PM To: amradio@mailman.qth.net Subject: Re: [AMRadio] Modulation transformer ID and repair > Don's circuit didn't come out to good here so I redrew it and it can be > viewed at this link > http://wa5bxo.shacknet.nu\HAMPICTURES\mod-reactor-circuit.gif > > I pretty sure this is what you had in mind Don When I had my reactor in the 250TH rig, in the larger rack, I came up with around 49.9Hy @ 400mA by seriesing 3 chokes. two 20Hy's and a 9.9Hy @ 400mA. I had a 5uF choke tied between the high-side of the modulation transformer and the final side of the Class C B+ supply. The other end of the modulation transformer was tied directly to ground. What would be the difference? 73 = Best Regards, -Geoff/W5OMR _______________________________________________ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
