[Amps] Asynchronous coax matching transformer

[Ian White GM3SEK]

K5GW wrote:
>Hi all,in addition to the examples Larry offered, the scheme will also
>match impedances less than 50 ohms, down to 22.2 ohms if I remember
>correctly.
> 

Thanks to Larry and Gerald for pointing out that the series method is 
much more versatile than I had imagined.

>A two way power divider where two 50 ohm loads are in parallel
>requires a 25 to 50 ohm transformer which is easily handled with the
>series matching method.
> 
>The only down side is the difficulty in adjusting the matching sections.
>On the other hand, transmission line calculations via Smith Chart or
>computer program will give the exact lengths in degrees needed so
>tuning is not a real requirement anyway.
> 
Greg Ordy's program takes care of that, and also says when a match is 
not possible.

>If the sections are joined via coax connectors, you have to take into
>account where 75 ohms ends and 50 ohms begins. The connectors are
>invariably of a 50 ohm type and their internal length must be added to
>the 50 ohm part of the matching section.
> 
>The last issue is velocity factor of the coax and connectors. A serious
>builder will be prepared to confirm these quantities before cutting the
>matching sections to length.
> 
Connectors wouldn't seem to be a major issue up to 50MHz.  Wherever 
paralleled cables are required, I find it easier to not to use 
connectors at all, but to splice the cables by soldering.

>It is a real joy to go through the numbers and have the transformer turn
>out right on frequency.
> 
Oh yes!


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek