[Premium-Rx] New radio selection

[Tracey Gardner]

> There is one trend that both ham and commercial/military rigs
> have been following for decades, that is unfortunate for CW reception:
> the trend has been very much towards brick wall IF filters, which have
> wonderful specs but in the ears they result in horrible ringing, making
> it very tiresome to do CW on bands with lots of QRN's for extended 
> periods.
> IMHO both ham and commercial/military rigs are misusing DSP techniques
> to go even more in the direction of brick wall filtering with wonderful
> specs but horrible listenability. My solution to this trend is my
> own homebrew receiver with a homebrewed crystal filter designed for
> linear phase response.
>
> Tim N3QE
>

Hello Tim

With regard to your "brick wall" filter comments.
I bought a surplus Racal RA1792 a few years ago, specifically because it had 
a Racal 100Hz CW filter fitted.
I soon became disillusioned with this filter, as in apparent bandwidth 
terms, it performed a lot worse than the 250Hz filter in my Icom receiver.
After doing some investigation I discovered that the Racal CW filter was 
optimised for a  linear phase response and not for shape factor, which meant 
that it's skirts were as wide as a barn door.
I've been using an Inrad 125Hz filter, with a good shape factor,  in my 
AR7030 for some years now and that doesn't ring at all.
I'll be exchanging the Racal 100Hz filter for an Inrad one at some point in 
the future, so if anyone needs a "barn door" ?

Tracey G5VU