[time-nuts] Re: Commercial solution - 122.88 Mhz low noise source

[Bob kb8tq]

Hi

Does the Abricon have an EFC input? If so, rigging up a PLL to lock 
122.88 to 10 MHz is probably the best option.

Bob

> On Apr 3, 2022, at 7:57 PM, Jeff Blaine <KeepWalking188 at ac0c.com> wrote:
> 
> I've got a couple of Red Pitaya 122-16 SDR and want to discipline them to an external low noise GPSDO source.  Wanted to see if there were some easy solutions that fell into this category.
> 
> For the prior generation (QS1R), I had built a homebrew OCXO based on a custom low noise crystal from ICM and that worked great for the 125 Mhz application.  Unfortunately this Pitaya is a bit removed in Fc and ICM has been out of biz for several years now.
> 
> The RP's on-board oscillator is the respectable Abracon ABLNO 122.88 which runs about -115 dBc/hz at 100 Hz spacing and that's probably not a limitation for the unit.  Unfortunately the OSC is a bit too sensitive to external temp and wanders around quite a lot (+/- 5 PPM) compared to the homebrew OCXO - over the annual ambient temp range of (10-35C) (all datasheet referenced values). The Abracon unit is mounted on the board with the FPGA and sees additional temp range depending on other heat generation factors (FPGA loading).
> 
> I have a couple of commercial GPSDO on the bench now, so a pretty clean 10 Mhz GPSDO reference is available now.  And I've seen enough board discussion to know that a homebrew GPSDO solution is one of those "it's harder than it looks" things.  Hence the desire just to buy whatever is the silver bullet, as long as it does not require too much silver.  ha ha
> 
> Appreciate any suggestions.  TKs!
> 
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
> 
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