On 4/3/22 5:09 PM, Bob kb8tq wrote:
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
And what about moving off the board - so you don't have to chase the
temperature swings.
On Apr 3, 2022, at 7:57 PM, Jeff Blaine <[email protected]> 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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