[Elecraft] K3 ATU

[Don Wilhelm]

Chris,

The KAT3 (like other Elecraft tuners) is an L network type tuner, and 
should provide good efficiency.  For your particular situation, I 
suggest that you use something like the TLW application (from 
www.arrl.org) and calculate the L network configuration needed for your 
impedance range.  TLW will also give you efficiency numbers.  The 'fact 
of life' that deals with added loss due to signal routing on the PC 
board should be minimal, but if you add 5 or 10% additional loss to 
account for the physical mounting of the components, you should be 'in 
the ballpark'.

Yes, you will have to know the reactance before you can obtain the 
really correct answer.  L network tuners are generally more efficient 
than the common Tee type tuners, but I am generalizing here, and 
exceptions are always present.  The PI network is typically efficient 
too, but the output capacity required becomes very large at low 
impedances.  If you want real efficiency, consider a link coupled tuner 
(like the Johnson Matchbox), but you sacrifice convenience for improved 
efficiency figures - the link coupled tuner does not lend itself well to 
bandswitching or to an auto-tuning application except over a very 
limited range (one ham band or less).

73,
Don W3FPR

Chris G3SJJ wrote:
> Does anyone have any figures on efficiency of KAT3 for load impedances 
> of 20 and 200 ohms? (reactance not known at this stage.)
>
> Chris G3SJJ
>