you have either a bad rectifier or most likely the capacitors in the power supply are shot.. Mike K4XM ----- Original Message ----- From: "Tom Elmore" <[EMAIL PROTECTED]> To: <amradio@mailman.qth.net> Sent: Wednesday, October 13, 2004 12:34 PM Subject: [AMRadio] B&W 5100B Modulation Update
> Now that I have had some time to troubleshoot the B&W 5100B modulation here > is what I found. The B+ is around 600 volts with no modulation and I as > start to modulate and watch the scope when it reaches about 50% modulation > the B+ drops from 600 to around 400 volts. I changed the final and > modulator 6146 tubes and see the same results. The original modulation > transformer has been replaced with a Chicago Standard Transformer > Corporation # A-3891. When I remove B+ to the final's and terminate the > modulation secondary into a resistive load of about 6k ohms I still see a > significant drop in B+ as I start to bring modulation up. I don't have the > original mod transformer and the manual I have doesn't say what the > impedance should be. I have tried various other tap settings on the > transformer secondary and don't see much of an improvement in reducing the > amount of voltage drop. I wonder if it is possible that this mod transformer > just will not work with this unit. Anyone have experience with mod > transformers using 6146's as finals and modulators? > > Thank You > Tom Elmore KA1NVZ > Anchorage Alaska > > ______________________________________________________________ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net >
