[Elecraft] OT a bit: K3 Ant Tuner

[Jim Brown]

Actually, I suspect that they're designed for 50 ohms at least in part, 
because that's how they will be measured!  We try hard to present a 
matched load in the passband, but, as others observed, output stages are 
usually lower than 50 ohms and few antennas, even when matched by a 
tuner, look anything like 50 ohms away from resonance. So all we can 
really hope to gain by matching is to minimize loss in the passband.  
AND -- any performance specs and/or measurements at 50 ohms in and out 
are a fiction away from resonance, and with other than a 50 ohm source.

73, Jim K9YC



On 7/5/2019 11:37 AM, K9MA wrote:
> Bandpass filters are generally designed for 50 Ohm source and load 
> resistances, mainly because the actual source and load impedances are 
> usually unknown. These filters will only perform as advertised with a 
> 50 Ohm source and load. With real world impedances, you just have to 
> hope for the best.