[time-nuts] WWVB d-psk-r update. Seems a reasonable solution

Fri Mar 29 12:01:11 EDT 2013

Hi

Too much tuning range is easy enough to fix. Use a pot to set it on frequency and then hook it to the rest of the "stuff" with a fixed resistor. The gotcha would be if the poor thing drifts so much that it *needs* the wide range to stay in lock.

My guess is that you could buy a hundred VCXO's at auction for less than the cost of trying a dozen samples. 

Bob

On Mar 29, 2013, at 11:03 AM, paul swed <paulswedb at gmail.com> wrote:

> Indeed thats the problem. The VCO needs to be available grabbing something
> from ebays good for me but not you. Also the oscillator does need to be an
> integer of 240 Khz and Ideally divide on a separate chain to 1 or 2 Mhz so
> it could be multiplied to 5 or 10 Mhz as an example. Though for the d-psk-r
> thats not really of interest. A seperate item is that just ahead of the
> divide by 4 sine and cosine divide it may want a 50% duty cycle though
> thats most likely not true. Right now with 12 Mhz I do get 50% duty cycle.
> Could with 9.6 also.
> 
> Also I have as an example some 9.6 Mhz Vectron VCOs (How could you go wrong
> its a vectron) and the tuning voltage and range are simply to large. As I
> mentioned the homebrew osc is .5V for .1 Hz. The challenge I have with
> Digikey and Mouser is figuring out from the info what one to buy. I have no
> plans to try and buy 10 different oscillators hoping one hits some target.
> 
> So thats a piece of the puzzle. I did get much of the rcvr into ExpressSCH
> last night and will revalidate what I have in the diagram tonight.
> Regards and thanks for the coments.
> Paul
> WB8TSL
> 
> 
> On Fri, Mar 29, 2013 at 10:16 AM, Bob Camp <lists at rtty.us> wrote:
> 
>> Hi
>> 
>> Silly me to not dig all the way to the bottom of the data sheet ….
>> 
>> Looks like the auction sites may be the better choice.
>> 
>> Bob
>> 
>> On Mar 29, 2013, at 9:35 AM, dlewis6767 <dlewis6767 at austin.rr.com> wrote:
>> 
>>> The data sheet indicates the Fox924B is not voltage controllable, wever.
>>  -Don
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> -----Original Message----- From: Bob Camp
>>> Sent: Friday, March 29, 2013 7:37 AM
>>> To: Discussion of precise time and frequency measurement
>>> Subject: Re: [time-nuts] WWVB d-psk-r update. Seems a reasonable solution
>>> 
>>> Hi
>>> 
>>> There are a variety of VCXO's and TCVCXO's on the Mouser site. Prices
>> seem to range from $3 to $10 for the reasonable candidates.
>>> 
>>> 
>> http://www.mouser.com/ProductDetail/Fox/FOX924B-10000/?qs=sGAEpiMZZMsBj6bBr9Q9afDupvxlfd2QBmF8W0236Ww%3d
>>> 
>>> Is one of the many. It runs at 10 MHz, CMOS output, and actually *is* in
>> stock. Price is $6.41 for a single piece. I'm sure that a bit more digging
>> could get that down a bit. The auction sites also have similar parts.
>>> 
>>> Bob
>>> 
>>> 
>>> On Mar 28, 2013, at 9:01 PM, paul swed <paulswedb at gmail.com> wrote:
>>> 
>>>> OK it has been a while and I have promised to share results. In the next
>>>> few days I will put whats on paper into a schematic and share. I won't
>>>> dwell on all of the stuff from October to now. But several front end
>> rcvrs,
>>>> and several analog Costas loops were built using MC1496s and another
>> using
>>>> AD633 multipliers. Various other glue.
>>>> Nothing to rave about.
>>>> 
>>>> What I will detail is what I have done with quite common parts. But
>> what it
>>>> isn't is a kit or absolute or anything else. It can be made better.
>> Don't
>>>> doubt that for a second.
>>>> So what I do have are 4 pretty simple and reasonable parts of the
>> solution.
>>>> It really does work even on the east coast. Though MSF can really cause
>>>> issues ocasionally. One key part the costas loop is a design I stumbled
>>>> across from 1971 designers casebook electronics magazine ca herbst. Was
>>>> cleaning out old papers. The article left a lot of detail out. But the
>>>> principle is solid. It was surprising at how well it worked the first
>> time.
>>>> So what I will share with the Time-nuts are the following schematics.
>>>> 
>>>> A 60 KHz TRF receiver. Takes a 1uv signal and increases it to 2-4 V PP
>> with
>>>> AGC and soft limiter. It includes a 60 Khz xtal filter to set the
>> passband
>>>> and a tuned stage or 2. There are quite a few possibilities on the
>>>> internet. Tried a few. This is my version. But others would work just as
>>>> well.
>>>> 
>>>> Digital costas loop using nothing more the a 74hc86 quad exclusive or.
>>>> Resistors and caps to integrate.
>>>> 
>>>> The 12 Mhz VCO. Why 12? Thats the crystals I have. Boy can this area use
>>>> some help.
>>>> 
>>>> The divider. Cmos 12 Mhz to 0 and 90 degrees at 60 Khz. This is straight
>>>> out of any digital application manual. No magic at all.
>>>> 
>>>> When combined this creates a complete WWVB costas loop solution that
>>>> delivers a 60 Khz output locked to wwvb without the phase modulation. A
>>>> byproduct is the digital data from the new signal. Not used. Not even to
>>>> drive a led.
>>>> 
>>>> A path could be added that literally inverts or not the original AM
>> signal
>>>> so that spectracom 8170s and Truetime DC60s would work and recover time
>>>> correctly. That is a piece O cake.
>>>> 
>>>> So I will get this into a schematic to share over the next day or two.
>>>> By the way on performance the system handles sun rise and sets and keeps
>>>> ticking. Using a fluke 207 driven by a Rb ref to watch for failures.
>> This
>>>> is recorded on a 4 channel chart recorder program on a laptop. I have
>> used
>>>> the system to drive 2 X HP VLF 117s and they track as w
>>>> Lots of areas that might be improved AGC control and time constants.
>> Adding
>>>> a opamp to the 0 degree phase VCO control voltage and also adjusting
>> Time
>>>> constants. Though the 12 Mhz oscillator is really standard parts just
>> could
>>>> not find something reasonable and off the shelf. Digikey or Mouser
>> stuff.
>>>> something with 4 pins and a few $. By the way the control voltage is
>>>> .5V/.1Hz.
>>>> 
>>>> Regards
>>>> Paul
>>>> WB8TSL
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at febo.com
>>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>> 
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.