Arnold Additional German source for Minicircuits: http://www.industrialelectronics.de/
Bruce Bruce Griffiths wrote: > Arnold > > Arnold Tibus wrote: > >> Bruce, >> >> a very good summary! >> I do not know where I can get the proposed MinCircuits DBM >> here, I looked to all the big and international well known >> supplier of electronics parts with negativ result. >> >> If I have to import them from USA they could end up even above >> 100 $ ea. we have in Europe to take the high shipment costs >> and the 19% VAT into account. >> >> Is it likely to get used mixers with damaged diodes? >> >> Did somebody alredy look inside the metal case of the 10514A? >> Will it perhaps possible to reconnect the common ground connections >> such a way that the mentioned loops can be opened? >> >> >> > Not without changing the IF port connector or at least insulating its > shell from ground. > It may be easier just to construct you own mixer if you cant easily > obtain the PCB mount Mincircuits mixers that have separate IF and RF > grounds. > Another alternative is to use a couple of RF transformers to isolate the > mixer common ground from the RF source grounds and just have the mixer > IF port grounded via its coax cable. > If necessary you can easily wind you own RF transformers if you can > obtain suitable ferrite cores. > I thought that there was a Minicircuits distributor in > Germany(http://www.municom.de/products/products960.php). > Ulrich may know more about this. > >> Thank you Bruce, >> >> Arnold >> >> >> >> On Sun, 19 Apr 2009 08:51:50 +1200, Bruce Griffiths wrote: >> >> >> >>> Arnold >>> >>> >> >> >>> Arnold Tibus wrote: >>> >>> >>>> Bruce, Magnus, Pete, >>>> >>>> sorry for being late responding, but the Easter Holydays ... >>>> they are over now :( >>>> >>>> Thank you for the informations giving me some more ideas! >>>> >>>> I am still wondering about the specials of these mixers. >>>> What are their secrets, what the differences to "normal" or high level >>>> DBMs? >>>> Is high level a criteria? >>>> >>>> >>>> >>>> >> >> >>> The dc offset at the mixer IF output (a measure of the diode matching >>> and transformer balance) should be low as should its drift. >>> The real criterion is low mixer phase noise particularly at low offset >>> frequencies. >>> The 10514 and 10534 are reputed to have low flicker phase noise. >>> >>> >> >> >>> Using a high level mixer as suggested by NIST does have the advantage of >>> allowing a preamp with higher input noise to be used to amplify the low >>> pass filtered IF port output. >>> >>> >>>> There are some companies selling the 10514A with SMB connectors. >>>> I have no idea what is a good or reasonable price fore and if I am running >>>> into possible risks to get deaf ones, for totally around $ 100,- ? >>>> >>>> >>>> >>>> >>> That price appears significantly higher than the Minicircuits price: >>> http://www.minicircuits.com/pdfs/ZP-10514.pdf >>> However there is no guarantee that the modern 10514's use discrete >>> diodes or what their flicker phase noise characteristics are. >>> >>> >> >> >>> A mixer which has a common IF, LO and RF grounds is susceptible to low >>> frequency ground loop noise. >>> However you can use RF transformers at the RF and LOP ports to break the >>> ground loops. >>> >>> >>>> In may 2007 there was aleady a short discours about the 10514A. >>>> Rick mentioned that today it could be possible to build a considerably >>>> better >>>> design with currently available technology. >>>> >>>> Does it mean it is really possible to build a DBM with currently available >>>> diodes, transformer cores etc. with similar or better characteristics >>>> as the old known commercial types? Or did he think to special chip >>>> designs? >>>> Are there no real merits anymore with the famous old hp 10514A? >>>> >>>> >>>> >>>> >>> They were widely used for such measurements and their phase noise was >>> well characterised. >>> You can achieve better diode matching with monolithic diode quads, >>> however the flicker noise of such quads is reputed to be higher than >>> equivalent discrete diode quads. >>> >>> >>>> Would be interesting to learn more about. >>>> >>>> Arnold >>>> >>>> >>>> On Tue, 07 Apr 2009 11:40:41 +1200, Bruce Griffiths wrote: >>>> >>>> >>>> >>>> >>>>> Magnus >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>>> Magnus Danielson wrote: >>>>> >>>>> >>>>> >>>>>> Bruce Griffiths skrev: >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> Pete wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>> Arnold, >>>>>>>> >>>>>>>> I have had good experience with the SYPD series >>>>>>>> from Mini-circuits. I have not seen any used, but >>>>>>>> their new cost is reasonable. They do several things >>>>>>>> well e.g. the DC offset on the units I received is >>>>>>>> <1mV & they produce >2V p-p when driven @ >>>>>>>> +7dBm. >>>>>>>> >>>>>>>> Pete Rawson >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> 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. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> Pete >>>>>>> >>>>>>> These are OK except when one needs to isolate the IF ground from the RF >>>>>>> grounds to avoid low frequency ground loop problems. >>>>>>> The RPD and MPD through hole series are better in this regard as they >>>>>>> allow the IF ground to be isolated from the RF grounds. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> It should be noted that several of their SMB mixers have separated >>>>>> grounds, but it is not documented in their datasheets. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> The flicker phase noise characteristics of the mixer/phase detector >>>>>>> should be measured as some mixers/phase detectors have lower flicker >>>>>>> phase noise than others. >>>>>>> The termination of the IF port will affect the mixer phase noise. For >>>>>>> offset frequencies < 100kHz a capacitive termination of the IF port >>>>>>> which reflects the sum frequency back into the mixer reduces the mixer >>>>>>> phase noise. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> It essentially sees a very low impedance at those frequencies. >>>>>> >>>>>> My experiments with capacitive loading of mixers basically indicates >>>>>> that the actual low-frequency slope of an unloaded mixer does not >>>>>> change, but the capacitor load filters the sum-frequency (with >>>>>> overtones) while a resistive 50 ohm load just loads the amplitude down >>>>>> and gives no significant change to performance. Optimum performance out >>>>>> of a mixer in my experience comes from fairly high-impedance load at low >>>>>> frequencies with a direct capacitive loading for filtering effects. >>>>>> >>>>>> A non-filtered response is quite interesting to see with a fairly slow >>>>>> beating frequency occuring. Kind of soothing waveforms floating slowly >>>>>> as waves over the scope. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> The effect of reflecting the sum frequency back into the mixer is >>>>> documented in some Watkins Johnson and HP/Agilent appliction notes. >>>>> It can be very effective even at microwave frequencies. >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>>>>> The tradeoff is that the mixer output at higher offset >>>>>>> frequencies is attenuated by the IF port termination. >>>>>>> Terminating the IF port in a capacitor reduces the RF port impedance, so >>>>>>> that a low value series resistor (22 to 39 ohms - select for lowest >>>>>>> VSWR) is then required to improve the RF port VSWR. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> Which in improves phase-stability as reflected waves has less impact. >>>>>> -3 dB pads have also been used by the good folks over at NIST at one >>>>>> time. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>> >>>> >>>> >>>>> The best combination is a series resistor plus an attenuator pad. >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>>>>> Terminating the IF port with a capacitor also alters the mixer gain (as >>>>>>> a phase detector) so this needs to be measured in conjunction with the >>>>>>> noise >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> Well... the normal 50 Ohm loading alters the mixer gain... not the cap. >>>>>> But since the normation is towards 50 Ohm... ah well... >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> 10514 and 10534 mixers using discrete diodes supposedly have lower >>>>>>> flicker noise than mixers using integrated quad diodes. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> They however has common ground in their every day laboratory variants. >>>>>> There exist variants meant for production. However, they are not made >>>>>> out of that exquisite components, so their performance should be >>>>>> replicable, as have been pointed out before. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>> >>>> >>>> >>>>> The B versions intended for through hole PCB mount have separate grounds >>>>> for all ports. >>>>> These don't seem to be as widely available as they once were although I >>>>> have an HP10534B one. >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>>>> Cheers, >>>>>> Magnus >>>>>> >>>>>> _______________________________________________ >>>>>> 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. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>> >>>> >>>> >>>>> 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. >> >> >> > 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. > > _______________________________________________ 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.
