[time-nuts] wwvb d-psk-r updated general purpose reciever

paul swed paulswedb at gmail.com
Fri Nov 1 16:10:23 EDT 2013


Sorry to say the png attached will not magnify.
Here is the schematic in expressPCB form that does show the detail.
Regards
Paul
WB8TSL


On Fri, Nov 1, 2013 at 4:04 PM, paul swed <paulswedb at gmail.com> wrote:

> Hello to the group. It has been a while since I have sent anything. The
> last was the wwvb regenerator for time clocks.
> However I have been working on a general purpose wwvb receiver. One that
> is inexpensive, uses parts available today, is inexpensive, single supply,
> low power, and uses parts I don't need a microscope for. There are lots of
> older designs out there and at least one quite nice design is by one of our
> fellow time-nuts that started me thinking. But many of the designs use
> inductors that have become difficult to obtain.
> As much as I would have loved to hack one of the one chip wwvb clock chip
> wonders they simply did not work out. They are hot receivers actually
> because there was no way to pull the amplified wwvb signal out. Tried a
> number of schemes like 2 chips in parallel. One detecting the AM signal and
> providing AGC control to chip 2 that had no AGC or demod caps.
>
> The design here is hot enough 8 uv region. Draws far lower current than
> the IC versions I have built using opamps at least 1/10th. Has AGC and can
> hold a range up to 1000 uv without distortion. Thats the highest I have
> seen near Boston recently. The design is quite classic.
>
> Uses J309 FETs and 2n3904 transistors. The two exotic parts are mouser IF
> transformers and in reality the pesky 60 Khz watch xtals. 25 for $6 as I
> recall. What I learned here is that they must be very lightly loaded to
> allow a parallel cap to tune them to 60 Khz. They are sharp and that may be
> the hardest part of the whole receiver. Easy if you have a sig gen. I will
> bet quite tough if you try off air.
>
> [image: Inline image 1]
>
>
> There are several buffered outputs for general use. I have added one of
> the 8160b analog decoder to give me the old AM signal data useful for the
> initial PSK search. There are two limiters being tested right now. The
> MC3356 and the AD806 to give a very hard clipped carrier.
> Both signals will be used for the next step of development in the d-psk-r
> and that is a digital approach to correcting the phase shift changes. Any
> way this goes this is the base receiver for me from now on.
> Even if the digital approach never works I can add in the digital costas
> loop I have shared and maybe one day the full analog costas loop that gave
> me so much trouble and that the digital costas loops has given me a serious
> clue to.
> Regards
> Paul
> WB8TSL
>
>
>
>
>
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