[time-nuts] Re: Brooks Shera GPSDO

[Arnold Tibus]

Very interesting to read about this good old design!

I have still a board for the Brooks Shera GPSDO and I would like to
complete it, but I cannot find the described 24 MHz/ 6 MHz Oscillator.
So I have some questions to it.

Is it neccessary that these frequencies are exact and running synchronous?
Are there special tcxo available which would fit?
Could I run this board as well with other (e.g. higher) frequencies and
of independent oscillators?
Are there improvements in meantime?

regards,

Arnold, DK2WT


Am 20.02.2022 um 03:11 schrieb glen english LIST:
> Larry, Take a look at Brooks Shera's article in QST. you might know of it.
>
> In my opinion, this has been the 'best ever' description of rolling your
> own.
>
> The July, 1998 issueBrooks Shera, W5OJM, titled, "A GPS-Based Frequency
> Standard. <https://www.qsl.net/n9zia/wireless/QST_GPS.pdf>"
>
> https://www.qsl.net/n9zia/wireless/QST_GPS.pdf
>
> I build several of these and they made "good" GPSDOs
>
> much has been written about this, and emulating it for other hardware.
>
> https://k6jca.blogspot.com/2018/12/simulating-brooks-shera-w5ojm-gpsdo.html
>
> https://github.com/k6jca/Brooks-Shera-GPSDO
>
> u can still buy the original PCB PCB
>
> http://www.a-aengineering.com/gps.htm
>
>
> On 20/02/2022 10:59 am, Larry Gadallah wrote:
>> After poring over the several valuable references people have posted
>> here, it seems that even the common commercial GPSDOs have
>> implementation problems, so it seems like there's no (financially
>> viable) off the shelf solution.
>>
>> It would indeed be convenient to have a kit option, but I'd image the
>> potential marked for a GPSDO kit is vanishingly small.
>>
>> FWIW, I started with a VE2ZAZ board and an Isotemp OCXO and a Motorola
>> receiver of questionable provenance. Since then I've gathered an HP
>> 10811D and I have an HP E1938A coming (I think), so I have only so far
>> gathered some essential components that I hope are competent.
>>
>> On Sat, 19 Feb 2022 at 07:13, Bob kb8tq <kb8tq at n1k.org> wrote:
>>> Hi
>>>
>>> Building a kit is very different than a from scratch design. A
>>> Heathkit (to extend the years ago ham radio analogy) radio
>>> was an option when you shopped for your Drake. Building it
>>> would give you some experience.
>>>
>>> The Heathkit *design* was done for you and all the complicated
>>> higher level stuff was worked out / tested out / reworked / retested
>>> by somebody else. As long as you put it together correctly, it
>>> worked and was a good radio.
>>>
>>> These days there aren’t a lot of folks selling kit GPSDO’s. Even
>>> the kit radio business isn’t what it once was. “I’m going to do
>>> a GPSDO” these days generally means a scratch design.
>>>
>>> Bob
>>>
>>>> On Feb 19, 2022, at 2:41 AM, Bill Beam <wbeam at gci.net> wrote:
>>>>
>>>> But there is a magazine article....
>>>> <https://www.qsl.net/n9zia/wireless/QST_GPS.pdf>
>>>> By Brooks Shera, W5OJM.  QST July, 1998.
>>>>
>>>> Following this article I built my unit in 1998 using his PCB and a
>>>> Motorola UT+.
>>>> It has been running almost continuously since then - almost 25 years.
>>>> It has been thru several HP 10811 and 10844 oscillators during that
>>>> time.
>>>>
>>>> Even though Brooks is SK his GPSDO is still running.
>>>>
>>>> Regards.
>>>> Bill, NL7F
>