[time-nuts] FE-5680A Voltage tolerance
EWKehren at aol.com
EWKehren at aol.com
Fri Jan 20 08:01:03 EST 2012
Starting Sunday I will do some voltage tests, giving up on aging test, nine
weeks is long enough. I will se if the next one is as good, how ever I do
not understand all the talk about running it at a lower voltage. Loosing
regulation will definitely impact performance. I have not analysed my unit
but a 13.3 V LDO was reported. In my opinion that says what the lower limit
is based on sufficient margin for that regulator. What is wrong with 15
Volt? I am running the unit right out of the switcher no extra filtering and I
can say based on my tests that it is good to 1 E-12. I also se a 4 Hz loop
that will be there with any kind of regulation. That is why I will include
a clean up OCXO with a 100 second analog filter. That OCXO will get special
attention in its supply voltage regulation. Starting out with 15 Volt
gives me enough head room. I am using a $ 10 12 V 2 A switcher cranked up to
In a message dated 1/20/2012 7:43:16 A.M. Eastern Standard Time,
nerd at verizon.net writes:
It is not surprising that many of these units work alright below their
voltage. I would imagine that the internal regulators, in addition to
voltage, are also there to keep voltages stable, and thus help with unit
stability. So, a unit may work fine, and be able to meet stability specs,
operated slightly below the 15 volts, PROVIDED that that lower input
provided by a stable, regulated supply. If I were the manufacturer, I
want to have to rely on the supply being perfect, I would want to do my
regulation as they have. These are used in a system where the power
drives many items and there are voltage drops due to wiring, backplanes,
etc as well as variations due to load changes. You may be able to have
work fine slightly below spec'd voltage, but if you do that in a system or
an unregulated supply and all bets are off. Give the unit decent power
its specified input range and then that's one thing you don't have to
On 1/20/2012 6:09 AM, Rob Kimberley wrote:
> I've had one of mine running on a bench supply for about 2 days now. Have
> just tried turning the voltage down, and things started to get unstable
> around 12.5V. It didn't drop out of lock however until about 9V.
> Rob Kimberley
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Peter Gottlieb
> Sent: 20 January 2012 04:16
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] FE-5680A Voltage tolerance
> When I got my first unit I hooked it up to my protoboard power supply
> is rated at 15 volts 0.5 amps and 5 volts 1 amp. I was annoyed that it
> 10 minutes to lock up until I realized the 15 volt supply was down near
> volts. Oops. Substituting my small B&K bench supply (good for up to 3
> amps) resulted in a lock in under a couple of minutes. Perhaps my unit's
> internal adjustments are still just about right. It would be nice to get
> the alignment procedure for the thing, but I suppose, fat chance of that.
> On 1/19/2012 6:45 PM, gonzo . wrote:
>> Experiment for the day.
>> I thought I'd follow Dons quote and see how tolerant my unit is.
>> My benchmark is at 15.5V it locks in about 3min.
>> I backed off the supply to 10.8V and the lock time (from cold) is 8min.
>> I thought this was interesting given several people report they are
> to get a lock when running lower voltage.
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