NIST used off the shelf RF transformers in their mixers based on diode connected (collector connected directly to base) 2N2222. The transformer impedance ratios (!:5 IIRC) are specified in the papers on the mixer performance. Suitable transformers are made by Minicircuits and others.
Bruce > On 20 December 2018 at 07:04 Jerry Hancock <[email protected]> wrote: > > > Thanks to all that replied, lots of good info which will take me months to > sort through, especially the link to Jürg Kögel looks helpful as well as a > note from Bert. > > Attila, Yes, more phase noise than long term though this is really an > exercise to get a better understanding of oscillators and measurement > techniques. > > The 2n2222 mixer sounds like another H-mode, I’ll have to look at it. It > probably uses self-wound, micro-sized bobbins which will be a challenge for > me :-]. > > Bob, I think you were the person who pointed me to the loose PLL a while > back. The circuit I am building used a gain of 300ish (30k/100) and I expect > that to really clip when unlocked. I have a 10-turn variable in the circuit > to bring it close initially. > > Another question or if you can point me to the method, if you are using > quadrature signals, is the measurement then the geometric sum? Or do you mix > them back together? I am using a 3457a on the PD after an amp right now and > I would think you would need either another meter, which I have, or a > scanner, again I have both. > > My N2PK VNA uses two 24bit, low noise ADCs (LTC2410) for the same purpose > more or less. It has effectively two DC receivers with two DDS. I can throw > away the DDS and mixers and just read the DC voltage. I have a second N2PK > board I never finished as I planned to use another master oscillator on it > with lower PN, but I needed a couple of parts and my tremor made SMD > soldering difficult. This was one of the drivers for my interest in phase > noise. Now that I think about it, I can repurpose the second board, bypassing > the MC1496 mixers. They are filtered to be close to DC within a few hz and > has -135dB noise floor. I can even change the input filter to use the 220 > ohm/.0046uf R/C recommended. > > I wish there was a way to use or modify one of my 8568B Spectrum analyzers to > do this. > > Regards, > > Jerry > > > > On Dec 19, 2018, at 7:57 AM, Attila Kinali <[email protected]> wrote: > > > > Hoi Jerry, > > > > On Tue, 18 Dec 2018 23:18:42 -0800 > > jerry <[email protected]> wrote: > > > >> I'm playing around with various methods of collecting data for > >> oscillator testing and would like to try the loose PLL which > >> requires a phase detector (PD). > > > > I guess you are looking more into phase noise than stability? > > > >> I'm testing an AD8302 but that has a flat spot around 176 to 180 degrees. > > > > All phase detectors exhibit non-linearity in some form or other. > > If you get all the way to +/-176° with good linearity, then be > > happy. If you need more than that, then you have to either use > > two phase detectors that are driven with a reference that is 90° > > apart, or you have to digitize the signal and do the same in digital. > > > >> One of the papers I read recommended the subject PD but it is out of > >> stock everywhere, including the subs. One Minicircuits PD is in stock but > >> pricey. I can try a double balanced mixer like the SBL or TUF series > >> (which > >> I have on hand) but I thought maybe someone on the list has the subject PD > >> they dont need. If so, please send me a note. > > > > There is a decent alternative: Use two transformers and 4 2N2222 to > > do your own mixer. The quality of it, according to NIST[1] is pretty > > good. I assume that any other NPN transistor of similar make-up will > > also do and lead to same/similar performance. > > > > You might also want to have a look at Enrico's Mixer Tutorial[2] > > > >> I'm slowly gathering parts for Riley's small Dual Mixer Time Difference > >> test kit but it will take some time which I'm unfortunately running out > >> of due to mild Parkinsons getting in the way of SMD soldering. I've used > >> my HP 5371a in the past but it sounds like a jet engine. I recently > >> ordered a TICC as well. By the time I'm done I probably will have > >> purchased more than a commercial product, ha! > > > > Jürg Kögel did a redesign of the Riley DMTD earlier this year, > > which looks very nice. And the measurements I've seen are very > > impressive (it's on par with the best state of the art I am aware of). > > So you might want to contact him and see whether he has some board left. > > > > Attila Kinali > > > > > > [1] "Residual PM Noise Evaluation of Radio Frequecny Mixers" > > by Barnes, Hati, Nelson, Howe, 2011 > > https://doi.org/10.1109/FCS.2011.5977868 > > http://time.kinali.ch/mixers/residual_pm_noise_evaluation_of_radio_frequency_mixers-2011-barnes_hati_nelson_howe-05977868.pdf > > > > [2] "Tutorial on the double-balanced mixer" > > by Enrico Rubiola, 2006 > > http://arxiv.org/abs/physics/0608211 > > -- > > It is upon moral qualities that a society is ultimately founded. All > > the prosperity and technological sophistication in the world is of no > > use without that foundation. > > -- Miss Matheson, The Diamond Age, Neal Stephenson > > > > _______________________________________________ > > 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.
