>
>Tom says:
>
>>I'm amazed so many people buy tuners instead of building them, or
>>using stubs.
>
>Here we definitely agree. Starting from the R + jX you need to match, a
>dedicated tuner can be designed to have the lowest operating Q for a
>particular
>impedance transformation ratio.
>
>
> >but moving the balun to the input of the tuner does NOT help balance
>
>Just how well balanced are the loads anyway? I suspect that generally,
>probably
>to around 10% mismatch isn't uncommon.. i.e. the impedances from each side to
>ground don't match by 10% or possibly more.
>
/\ My guess is more due to proximity effect of buildings, trees, bushes,
on and on. Thid is where the input coax-choke/balanced-L design shines.
>
> >Tuners are probably one of the most difficult pieces of gear to
> >engineer, because the frequency and impedance ranges are so
> >wide.
>
>This is because the commercial tuner has to be an egg laying, milk and wool
>producing flying pig that swims. ...
/\ hear, hear.
cheers
- R. L. Measures, 805.386.3734, www.vcnet.com/measures.
end
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|