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

Bob kb8tq kb8tq at n1k.org
Thu Jul 26 20:36:04 EDT 2018


Hi

90 db will not drive the ADEV nuts, but it still will be a lot worse than a normal standard will deliver, even at 
120 db down, if the offset is a bit above 1 Hz you will still see it in an ADEV plot. 

Bob

> On Jul 26, 2018, at 5:40 PM, Scott McGrath <scmcgrath at gmail.com> wrote:
> 
> True but if you use a good switch or PIN 90 db of isolation is easily achievable.   Yes the spur is still there but it’s 90 down and will not affect ADEV as badly.
> 
> You could drive it further down with two switches with the alternate standard connected to 1 port and a termination to the other.  So a switchover would switch to the alternate port and the backup path would switch from termination to backup source.    This would easily buy you 120-130 db isolation assuming use of good cabling and proper routing, grounds etc
> 
> After all this IS time-nuts after all
> 
> Content by Scott
> Typos by Siri
> 
> On Jul 26, 2018, at 6:23 PM, Van Horn, David <david.vanhorn at backcountryaccess.com> wrote:
> 
> Not quite what you are looking for, but I implemented a pair of thunderbolts with no common parts (dual antennas power etc) into a simple RF switch.
> The production manager flipped the switch on Mondays, and if either system wasn't working I had a third system in a box ready to replace.
> So for any failure of the two live systems, all he had to do was flip the switch and call me.
> 
> 
> -----Original Message-----
> From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of W7SLS
> Sent: Thursday, July 26, 2018 1:46 PM
> To: time-nuts at lists.febo.com
> Subject: [time-nuts] 10 MHz 'failover' switch?
> 
> 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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