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

[James A. (Andy) Moorer]

Isn't what you mean by the "preselector" really the RF Filter, part number 
280093, shown in figure 6-1a of the 8716 manual as "Type 791616 RF Filter"? 
It is numbered page 6-1a. It is exactly as you describe - one BIG 
featureless box. There are no controls, no band select wire or shaft - 
nothing going in except the RF from the antenna. No digital nothing on the 
inside. No motors - no active components. If you open it up, you will find 
inductors and capacitors and a couple of zeners.

There is a thing called the WJ-9073-2 "Tracking Preselector", but that is a 
separate 1U unit that goes with the "B" model of the 8716. It takes a serial 
data input from connector J5 on the back of the 8716B. It has all sorts of 
good stuff on the inside - five separate RF filters, all precisely tuned by 
banks of varactors.

James A. (Andy) Moorer
www.jamminpower.com

----- Original Message ----- 

> 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