Ray, You are exactly right. With 2 op amps in an 8-pin dip and 4 in a 14-pin dip, I have gotten lazy :) 73 Tom W0IVJ
Ray Andrews, K9DUR wrote: >Tom, > >Actually, it could be done with a single op-amp. Feed one signal into the >"-" input of the op-amp & feed the other signal into the "+" input & you >have a subtraction circuit instead of an addition circuit. Feed the ALC >signal through a series resistor to the "-" input and connect another >resistor from the "-" input to the output terminal of the op-amp. Feed the >SWR signal through a series resistor to the "+" input & connect another >resistor from the "+" input to ground. You just have to juggle the resistor >values to balance the 2 signals properly. It has been way too many years >since I did any circuit design work (been doing software design for 25 years >or so) to remember the formulas for calculating the resistor values. I >would have to look them up, but they should be in any op-amp circuit design >reference book. > >73, Ray, K9DUR > > > > > > > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
