Hi > On Jan 18, 2017, at 1:08 PM, jimlux <[email protected]> wrote: > > On 1/18/17 8:56 AM, Bob Camp wrote: >> HI >>> >>> the first time we ran the test (using a Keysight 33622 signal >>> generator) we saw significant 2nd and 3rd harmonics (50-60 dB down, >>> but easily detectable). A quick review of the data sheet.. Oh, the >>> signal generator spec is only -43 dBc for frequencies above 10 >>> MHz. >> >> So even a pretty expensive signal generator still has “loud” >> harmonics if judged at the -60 dbc level …. >> > that's actually an inexpensive ($7.4k) function generator (with good > performance for a function generator that does a lot of stuff, except > generate chirps at the right rate).. > > A $8k Keysight N9310 is -30dBc > > A R+S SMA100 specs -30dBc (actually does better) > > A $23k Keysight 8663D specs -55dBc (at 1 GHz) > > > > >>> >>> Another case where low harmonic content is when doing two tone IMD >>> tests - if the sources have significant harmonic content, you might >>> be seeing intermod between the harmonics of the source, rather than >>> intermods between the fundamental of the source. >> >> Which is one of the reasons a lot of IMD test setups have a variety >> of filters in them. >> >> >> These also are a pretty common item on eBay, at ham fest, and in your >> typical RF junk box. 10.7 MHz IF filter cans can fairly easily be >> tuned down to 10 MHz to custom roll bandpass filters. > > Yeah, but it's easier (cheaper if you're paying for labor) just to buy a box > of 10 filters at $30/each and stack them
Be *very* careful cascading those Min-Circuits filters without putting some sort of isolation between them. You can get all sorts of wonky results as the reactances in one mis-terminates the reactances in another. Bob > _______________________________________________ > 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.
