[time-nuts] Minicircuits 10% discount in December

[Richard (Rick) Karlquist]

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