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

[Brooke Clarke]

Hi Tim:

How about opening the hood and take a photo of the engine?
I doubt there's any motors in there.  More likely fixed L and C components or 
filters that are switched in or out of the coax line.  My SDR-IR receiver uses 
small mechanical relays to switch in or out different filter sections.  Each 
relay is in series with all the others so you can insert different combinations 
of low pass and high pass filters.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Tim Shoppa 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