Tom Clark, K3IO wrote: > Gerhard -- the discussion between you and Bruce has been very > interesting. I asked a VLBI colleague to look over your design and he > had this comment. > In VLBI, H-Maser frequency standards used to generate local > oscillators at microwave frequencies. We have problems with amplitude > modulation being converted to phase modulation when hum is present. I > notice that Bruce also uses transformers. Comments from both of you > will be eagerly awaited! > > Thanks Tom. I notice the Gerhard Hoffmann circuit has a > transformer on the outputs. Wenzell also uses transformers and we > have found them to be a problem if there is any stray AC mag. field > around. We have added some magnetic shielding to the UpDown > converters to reduce the 60/120 Hz modulation which results if the > UpDown is close to a another piece of electronics with a AC fan or > AC transformer. I don't think 60/120 Hz is a problem for VLBI2010 > but it can be a problem for mmvlbi. > > Tom
Another problem with ferromagnetic materials such as transformer cores and magnetic shields is magnetostriction. The resultant vibration can modulate component parameters. Bruce _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
