alan.b.pearce@stfc.ac.uk wrote:
> A suitable balun is normally a few turns of wire on a ferrite core.
> The gauge of wire and core type both affect the characteristics of the
> balun. However it is worth getting down to your local library and
> having a look at an ARRL or RSGB handbook to see what the amateur
> radio guys do at 70cm for baluns, as there are tricks that can be
> done with coax or PCB traces to achieve similar results.

You can definately make your own baluns.  Wrapping a differential pair
around a ferrite core is a common trick.  However, at his power levels and
frequency you won't be able to make anything as small as what you can buy
off the shelf.

Various folks make baluns intended for exactly this purpose.  They can have
footprints down to about 1206 size.  Coilcraft shurely makes some.  I just
checked, and in one 434MHz receiver I worked on we used a Mini-Circuits
TC1-1-13M.  There's no way you can make something that small by hand.  The
well defined specs in the datasheet would also be rather difficult to match=
..


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