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

[ghf at hoffmann-hochfrequenz.de]

Am 2022-04-04 2:09, schrieb 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.

Yes, the Abracon ABLNO has EFC. And it is quite good, esp. considering 
its
price of €12 up. I have the older RedPitaya, still with the 14 bit ADC. 
If it
gets an external sample clock, it expects LVDS. Can be jumpered.
I guess that this is still the same.
Changing that from 122.88 to 100 MHz eases up things considerably. For 
144 Mhz,
the first LO can be 100 MHz, and for 432 MHz I'll use 100 MHz * 4 with 
SAW filters.

In the current DUBUS, I have published a tiny LMX2594 10 to 15000 MHz 
synthesizer.
The next issue will show the companion 100/300 MHz clock generator that 
can be
locked to external 10 MHz. It uses an ECS 100 MHz oven for ~€100. The 
Abracon
should work, also. (www.dubus.org)
I'll need another board spin. Too much +-10 MHz contamination on the 
output
if locking is used.

The PLL will be probably 74lvc161 + 4046 + Bleeder. At least no 
programming.
9046 seems no longer to exist, unless you buy 250 pcs. from Rochester.

AD/Hittite HMC1031 is cute, but it is an incomplete solution. When there 
is
no external reference, I would like Vtune from a 10 turn pot and not 
from the
supply rail. Just 2 pins more and it was ideal.

regards, Gerhard

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