[time-nuts] 10 MHz 'failover' switch?

Bob kb8tq kb8tq at n1k.org
Thu Jul 26 17:45:19 EDT 2018


Hi

One interesting subtlety making something like this:

What if the two inputs aren’t quite on the same frequency?  Purely as an example, say they are 1 Hz off from each other. 
If you have 60 db of isolation in your “switch” you get a 1 Hz offset spur that is 60 db down. Even something much further 
down is plenty to mess up the ADEV of the output.

Bob

> On Jul 26, 2018, at 4:33 PM, Scott McGrath <scmcgrath at gmail.com> wrote:
> 
> Build one yourself,   Detector diode on primary RF input when output drops use a rf relay or PIN diode switch to fail over to backup standard.    All thats needed is a crossing detector and relay / switch driver
> 
> Yes there would be a momentary hit but it would work.
> 
> Content by Scott
> Typos by Siri
> 
> On Jul 26, 2018, at 4:13 PM, Bob kb8tq <kb8tq at n1k.org> wrote:
> 
> Hi
> 
> They are a pretty rare item. A more common approach is a disciplined oscillator that 
> will do failover on it’s inputs. That’s still a rare item, but at least a possible thing to find. 
> The equally big problem will be getting doc’s on one if you do find it….
> 
> Bob
> 
>> On Jul 26, 2018, at 2:45 PM, W7SLS <w7sls.scott at gmail.com> wrote:
>> 
>> Hello,
>> 
>> Looking for recommendation for a ‘failover’ or ‘redundant’ switch for 10 MHz distribution.
>> 
>>   Not really sure of the correct term.
>>   Something that sensed RF on primary 10 MHz, and then switched to secondary on fail of primary.
>> 
>> A brief search showed several very nice $$$ items, suitable for commercial applications,
>> but I wonder if there are some “last year’s” (but not last century) versions that would work for a home lab.
>> 
>> Context:
>> 
>> I have a GPSDO and a Rb source of 10 MHz.  
>> The power supply on the GPSDO failed (worked enough to light up the GPSDO, but not enough to lock).
>> I have a new power supply on order, but would be nice to have “insurance”.
>> 
>> Thanks in advance for the group bandwidth.
>> 
>> Scott
>> W7SLS
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> 
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