[Premium-Rx] What's in a WJ-8716 front end preselector?

[lrlayton at cox.net]

The PRE option that you have provides for automatic preselection of 1 out of 10 suboctave filters depending on what frequency you are tuned to. Most modern HF radios use a similar preselection scheme with either relays or  diodes being used to select the proper filter. My WJ-8716 has this feature, but unfortunately I have never found a schematic anywhere for this option.  

It is not he same as the 791616 RF filter, which is a 5 kHz to 30 MHz bandpass filter. 

Les Layton
Las Vegas, NV
 
---- Tim Shoppa <shoppa at trailing-edge.com> wrote: 
> I've got a WJ-8716 that has a front end preselector in it. It's a big
> metal box with obvious coax in, coax out, and some presumably digital
> and power wiring going into it too.
> 
> I'm familiar with, say, the R-390A's front end preselection: a bunch
> of octave-wide tunable LC narrow filters, with mechanical coupling
> between the main tuning and the slugs that tune the L's. Pretty
> nifty and perfectly obvious to me how iwoks.
> 
> Is this how a WJ-8716 preselector works too? Are there little motors
> moving slugs up and down inside as I tune, and banks of slugs
> for each octave? Or does it work on some entirely different mechanism?
> 
> Tim N3QE
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