Hej magnus Magnus Danielson wrote: > Bruce Griffiths skrev: >> Hej Magnus >> >> Magnus Danielson wrote: >>> Hej Arnold, >>> >>> Arnold Tibus skrev: >>>> 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. >>> It was not too hard to find their official list of representatives. >>> That is what I usually do besides the top catalog firms. >>> >>> Prices does not seem too bad... >>> http://www.minicircuits.com/cgi-bin/modelsearch?search_type=model&model=ZP-10514&tb_no= >>> >>> >>> >>>> Is it likely to get used mixers with damaged diodes? >>>> >>>> Did somebody alredy look inside the metal case of the 10514A? >>> You made me remember I needed too.... >>> >>>> Will it perhaps possible to reconnect the common ground connections >>>> such a way that the mentioned loops can be opened? >>> Yes. The grounds is separated on the PCB, so it is only on the front >>> plate that they actually interconnect when the BNCs screw tight. >>> >>> What's inside then? >>> >>> Well, there is 4 small torroid cores (as compared to the 10534A which >>> has only two cores). It also has 4 diodes (marked as HP 82) and 2 50 >>> Ohm resistors. >>> >>> The L and R ports have an isolational transformer each, with the 50 >>> Ohm resistor loading on the secondary side. A inner transformer then >>> follows, with two secondaries, hooked up like expected for a double >>> balanced mixer. Essentially this is a double balanced mixer with >>> additional isolational transformers and 50 Ohms terminations. >>> >> Its a little strange to terminate a mixer RF or LO port with 50 ohms to >> ground as usually the IF port termination largely determines (together >> with diode on impedance) the input impedance seen at the RF and LO >> ports. > > I was also reacting to this... > >> Are you sure that the first transformer isnt a splitter with the 50 ohm >> termination being the internal splitter termination? > > Yes. But looking more closely on them, they look like RF chokes, such > that common mode is suppressed. Having an RF choke there, loading it > with a resistor seems reasonable, as it needs to be loaded even for > lower frequencies to be useful. > > 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. > Do you mean a common mode choke with a common mode termination or perhaps a Guanella balun?
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.
