[GreenKeys] Dovetron mfg error (was Model 15 question)

[Nick England]

JIm's note on the BSP error plus whatever Dovetron manual scans I have come
across are at
http://www.navy-radio.com/rtty/dovetron.htm
I'll be happy to add more scans or borrow manuals to scan if anyone can add
to the list.
Cheers,
Nick England K4NYW
www.navy-radio.com


On Sun, Nov 17, 2019 at 11:04 AM Jim Haynes <jhhaynes at earthlink.net> wrote:

>
> The note is:  If you have the Binary Bit Processor BBP-100 Mark II as
> shown on drawing 75349 then inspect the bottom side of the PC board to see
> if there is an extraneous trace connecting the top ends of R21 and R22.
> By top ends I mean the ends that are on top if you hold the drawing
> vertically so it reads right side up.  The bottom ends are supposed to be
> connected together and to pin 6 of U11. The top ends are not supposed to
> be connected together.  If they are the threshold voltage will stay at
> 0 volts so the threshold correction circuit is inoperative.
>
> Then look at resistors R24 and R25.  These are supposed to be 10K
> resistors.  You may find they are 100K, because 1% resistors have
> an extra digit in the value.  If the colors are brown-black-black-orange
> you have 100K resistors and the unit will hardly work at all after the
> extraneous PC trace is cut.  Replace with 10K resistors, and they
> probably don't need to be 1%.
>
> This error may explain why some Dovetron demodulators get poor
> performance reports.  I guess it didn't get detected at the factory
> because the units with the errors do work with good signals, but
> not with weak and fading and noisy signals.
>
> Jim W6JVE
>         ---
>
>         "Ya can argue all ya wanna, but it's dif'rent than it was."
>         "No it ain't! No it ain't!  But ya gotta know the territory."
>                 Meredith Willson, The Music Man
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