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

[James A. (Andy) Moorer]

Does anybody have a schematic for this 10 suboctave automatic preselector?


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

----- Original Message ----- 
From: <lrlayton at cox.net>
To: "Tim Shoppa" <shoppa at trailing-edge.com>
Cc: <premium-rx at mailman.qth.net>
Sent: Wednesday, November 28, 2007 2:38 PM
Subject: Re: [Premium-Rx] What's in a WJ-8716 front end preselector?


> 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