Hi I would *think* that the phase noise out of the down converter channel would be the DUT + LO. If indeed you have DUT A + LO B and DUT C + LO D, you then have a lot of A + B vs C + D stuff to sort out ….
Bob > On Oct 17, 2020, at 2:48 PM, John Ackermann N8UR <[email protected]> wrote: > > FWIW, I have done PN measurements at 144 MHz with the TimePod and a > Frankenstein's laboratory lashup of 80 MHz ULN, HP doubler to 160 MHz, HP > mixer, and several amp and filter blocks. As far as I can tell, it worked > pretty well; at least, I could discern the PN difference among several > sources, some of them quite good. > > Not sure why you are doing two oscillators/mixers, though. I used a 5 or 10 > MHz reference directly into the TimePod, and the DUT fed through the mixer. > No need to increase the frequency of the reference to match the DUT. But if > you do want to mix both the REF and DUT channels, wouldn't it be better to > use a single source to drive both mixers? > > John > ---- > > On 10/17/20 8:59 AM, Gerhard Hoffmann wrote: >> I'm trying to make a quick frequency extender for a timepod. >> MCL PSC2-1 power divider, 2* SRA-1 7 dBm ring mixer, 2 DIL 80 >> MHz-oscillators >> The oscillators can drive the ring mixers with just a coupling capacitor and >> 50 Ohm >> load limiting resistor. It is still a square wave at the LO port, but the >> diodes in the mixer >> would square it up on their own. >> When there is no 5V-power, the oscillators are off and the LO inputs are >> connected >> to SMA connectors via the normally closed contacts of two reed relays. >> Then the whole thing is passive and needs two external synthesizers. >> Before I continue with the material I had in the junkbox, a quick question >> to those >> of you who have done that already: >> Are 7 dBm mixers like SRA-1 good enough or is 17 dBm an advantage worth the >> driver amplifiers? The usual signal generators max out at 13 dBm. >> I have 2 17 dBm SRA1-WH, but it would require slaughtering something >> unimportant. >> How close must the oscillators be in frequency? >> Have a nice weekend, >> Gerhard, DK4XP >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
