[Premium-Rx] WJ 8718A help

[lrlayton at cox.net]

Lee, 

I am looking at the preselector on my WJ8716 and don't see a chip with that number. I am assuming the preselector for the WJ8716 and 8718A are similar but I could be wrong. My preselector is part no. 796012 and the only chips I see are on the A6 board and they are common SN74LS42N and SN754538P types.

I don't have any data on the pre-selector option, but have been looking for a schematic and alignment info.

 I recently read some posts about the WJ8718 MPF version having clicks every 10 kHz and thought I would see if my receiver had this problem as I didn't recall anything like that. The only clicks I heard were at wide spaced intervals that I believe are switching points in the preselector. But I did discover a problem with higher background noise only between 800 and 1200 kHz than anywhere in the rest of the tuning range. This problem disappears when the A1preselector board is pulled, so I'm thinking the problem lies there. Maybe a switching diode or tantalum capacitor? Do you or any of the group have any thoughts on this or can help with some data on the preselector option?

Les Layton



---- L D Ritta <ufp at optusnet.com.au> wrote: 
> Hello All
> 
> I have been looking at the preselector option used in the WJ8718A and noticed they used a chip.
> A   841009 but my google search found nothing usefull. What is it, do you have a datasheet.
> 
> 
> 
> 
> 
> 73 Lee