Topband: Questions on K2ZJ preamp and audio filters

[Jim & Carolyn Kingsbury]

I have a K2ZJ preamp that I purchased some time ago and either never got any 
tech info or have lost it (old farts syndrome).  Does anyone know if the 
preamp had a built in matching transformer or was it just a straight 
preamp??

Second question---Is it possible to improve cw signal to noise ratio by 
building a audio bandpass or low pass filter to attenuate frequencies above 
about 1000 hz?  I'm not sure if this is practical or not or if it would 
help, but I'm sure some of you know the answer.

Thanks for any help and hope you all have a great 160 DX year.

73 Jim NW6S