[time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Mathias Weyland mathias at weyland.ch
Sun Jan 8 09:33:43 EST 2017

On 2017-01-04 11:08, Attila Kinali wrote:

Hoi Attila

> So it's the usual curiosity and the need to have a reference for
> your 23cm radios?

Yes exactly.

> Advantage of an GPSDO over an Rb is that you know it's on frequency,
> while with an Rb it can be off without you knowing it, if the
> electronics or the physics package is defect.

This is in line with what I've read. Maybe the decision to go for the
Rb was not the best one but I don't think that it's that bad either.
I was offered the opportunity to calibrate my modified Rb standard
against a fellow ham's two 10 MHz standards and his GPSDO.

> BTW: there is a whole new way of looking at statistics of time series
> in the field of time and frequency control, which you might find 
> interesting.
> The NIST Technote 1337[1] and NIST special publication 1065[2] give a 
> nice
> overview of the methods applied.

This is very interesting thank you for sharing those!

> Unfortunately, it's not that easy :-)
> I don't know the exact construction of the FE-5650, but usually the 
> physics
> package is just a normal aluminium microwave cavity, without 
> shielding.
> The mu-metal shield is usually the housing of the whole device 
> itself.

Hm I thought I had done my homework on this one but I never have
issues with being proven wrong. For what it's worth, here are two 
of the unit in question:


The shiny face plate is where I would be drilling. For what it's worth,
it is very light, nonmagnetic, does not look like the mu-metal I've
seen in disassembled hard disks and very much looks like machined
aluminum... Would a compromised mu-metal shield show during calibration
if the standard was physically rotated?

Best regards and thank you


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