Dave, You may want to look at the SG-503 Tektronix plug-in for a levelled sine generator. It goes to 250 MHz, and the full service manual with schematics is on my web site in the Manuals pages:
http://www.ko4bb.com/cgi-bin/manuals.pl I have one and it works as advertised. Great for scope calibration, not so great as a signal generator :-) Didier KO4BB > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of David C. Partridge > Sent: Monday, December 15, 2008 4:04 AM > To: 'Discussion of precise time and frequency measurement' > Subject: [time-nuts] OT: Levelled sine wave generator > > Sort of related, but only just - however the signal to noise > ratio here is so good that I feel impelled to ask. > > For 'scope calibration I'm considering building a levelled > sine wave generator. > > Ideally the specs I'm looking for are: > > o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz. > more would be better but not critical > > o Output levels from 0.5Vp-p(-2dBm) to at least > 4Vp-p(+16dBm) into 50R > (up to >6Vp-p(say +20dBm) would be better) > > o Output flatness levelled within 2% of desired output level > (+/- 0.086dB) > across the entire frequency range at the final > connector to the DUT > This will almost certainly mean an external levelling head. > > o Modulation - not critical, FM or AM might be useful. > > o A logarithmic sweep capability might be nice, but isn't necessary. > > o Frequency display - nice to have but output to external > counter is OK. > > Generating the basic signal is probably just a case of using > something like an HP VTO-8200, mixing it with 2GHz > (Mini-Circuits RMS30?), low pass filter, an AGC stage (see > below) and then amplify probably using an MMIC like the > Mini-Circuits ERA-2SM followed by an additional stage to get > the extra few > dB. For more accurate frequency control some sort of > synthesiser locked to > a reference might be in order (I had to get a time-nuts hook > in here somehow). > > The question is what should go in the sensor head? > > Logically I need to sample a proportion of the signal > delivered to the output connector, compare the output of the > sensor against a DC reference level telling it the desired > output level, and feed back a voltage to a > wideband AGC stage (any suggestions for this?) in the main > unit. I also > need to be able to detect that output is not levelled. > > Or should I just forget the whole idea and go talk to R&S > with a large cheque in hand? > > Cheers > Dave > > > _______________________________________________ > 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. > _______________________________________________ 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.
