[time-nuts] Minicircuits 10% discount in December

Dave M dgminala at mediacombb.net
Fri Nov 28 13:08:30 EST 2014

Thanks for the brief review of MiniCircuits stuff (I'm not connected with 
them in any way except as a customer).
Since you've characterized some of their parts, perhaps you could help 
answer a question that someone else posted, and one that I would like to 
have answered as well.
Have you measured the effects of DC current in the windings of an RF 
transformer, such as is seen if the transformer is in the collector circuit 
of an amplifier?  If so, could you provide a generalization of the effects, 
such as changes in frequency response, losses, etc.?

Many Thanks!,
Dave M

Richard (Rick) Karlquist wrote:
> On 11/27/2014 7:07 AM, Tim Shoppa wrote:
>> For a hobbyist doing things a few at a time, what advantage is there
>> to buying RF transformers made by Mini-circuits etc., vs winding
>> them using commonly available ferrite cores/binocular cores?
>> If I needed to do a production run of 1000+ boards with tiny SMT
>> transformers, sure, no problem buying them from mini-circuits or a
>> distributor etc. But for hobbyist stuff seems far more flexible to
>> wind them onesy-twosy using not so tiny cores and windings selected
>> for the particular application.
>> Tim N3QE
> You need the tiny cores to get the performance of the MiniCircuits
> transformers.  You just can't get the same bandwidth using macro sized
> "binocular" cores.  Now, if you don't need a lot of bandwidth, then
> what you are saying could make sense.  Another issue is stray
> capacitance.  Considerably lower with a tiny core.
> I have spent many hours characterizing MiniCircuits transformers
> beyond the data sheet specs, and dissecting them to learn how they
> do it.  They really do have a lot of rocket science in them.  In
> terms of the engineering I am buying (especially in a one-off
> application) they are ridiculously cheap.  And I say that as a fairly
> knowledgeable transformer designer in my own right.
> I do keep binocular cores around for higher power transformers, and
> for "emergencies" when I need a transformer "yesterday".
> Rick Karlquist N6RK 

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