Bruce Griffiths skrev:
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.
Bruce, many SMD mixers also have separate LO, IF and RF grounds. It is
just not documented in the datasheets. The recommended footprint pattern
(on say RMS-5+) actually ties them together. The MiniCircuit SMD mixers
I have been able to investigated (some of them have open bottom, so
looking in just takes a sharp eye) is not hooked up with a internally
forced common ground. A simple DC resistance measurement would indicate
if a particular model has their grounds connected together, but really,
they should fix their datasheets. I guess it just haven't been important
for them before.
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.
Actually, MiniCircuits web indicates two.
Cheers,
Magnus
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