Hello, I saw a post a while back where a group member was looking for a manual for the General Resistance Dial-A-Source units. I have a manual the covers the 40-50-60-70-80 series. I have uploaded it to www.ko4bb.com here: http://www.ko4bb.com/manuals/index.php?dir=09%29_Misc_Test_Equipment/General_Resistance I would also be interested in knowing how the various units perform these days, as good references are like wine, they get better with age! Best regards, Sam W3OHM