[time-nuts] FRK specs.....

dlewis6767 at austin.rr.com dlewis6767 at austin.rr.com
Sun Aug 12 14:54:40 EDT 2012


Bert:
Interesting.

I, too, have a couple of the HP 10811 oven-oscillators sitting on the shelf for several years, ....waiting for a project. I want to 'discipline' them, but really do not know how.

Could you kindly mark up the HP 10811 schematic and/or please tell me what to cut, ... what to jumper???

Thanks a lot!

Don Lewis
Austin, TX



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---- EWKehren at aol.com wrote:
> In the commercial world a PRS10 is most likely the best but for time nuts
> even at the surplus price in my opinion it is all hype and a waste of
> money. Have you looked closely at the specification and the design. Frequency
> accuracy can not be better than 1 E-12 since the OCXO is driven strictly by a
> DAC and the A/V is for time nuts nothing to write home about. Any digital
> loop controlling a Rb in tern with an analog loop controlling a selected
> HP 10811 or for that matter a Morion will outperform a PRS 10.
> I have a FRK-H controlling a HP 10811 that has an A/V below 1 E-12 from 1
> to 100 seconds, I modified the FRK loop and the 10811. On the 10811 it is
> easy to get to the bottom PCB and without un soldering any component or
> further disassembly cutting two traces and two jumpers you end up with a 2 to 12
> Volt tuning voltage, perfect for a FRK or M100.. A second option is to use
> a separate analog loop with a time constant suitable for your OCXO.
> By the way the FRK-H is not lower noise but factor 2 lower aging with the
> proper OCXO not an issue, since hopefully you discipline it with GPS.
> For 12 years I have used Shera in that application recently switching the
> DAC to a LTC1655. Has served me well over the years.
> Other Rb's will do also a very credible job. On one extreme a FEI 5680 is
> waiting to be integrated with a MV180 on the other extreme a HP5065 RVFR
> assembly will be integrated with a M1000 OCXO along with state of the art
> circuitry.
> Bert Kehren
>
>
>
> In a message dated 8/12/2012 8:09:54 A.M. Eastern Daylight Time,
> wa1zms at att.net writes:
>
> Thanks Tom.
>
> I agree, the SRS seems to be the best
> overall Rb except maybe on old HP if one is willing to spend about the
> same price on a 20 year old unit. The SRS units I bought for work were only
> $2700 with chassis, rack ears and multiple outputs.
>
>
>
> -Brian, WA1ZMS
>
> On Aug 12, 2012, at 3:17 AM, Tom Knox <actast at hotmail.com> wrote:
>
> >
> > Hi Brian;
> > There are a few decent rubidium oscillators short term like the SRS but
> none are great, in my humble opinion you are much better off disciplining a
> good quartz oscillator off your LPRO.
> > Best Wishes;
> > Thomas Knox
> >
> >
> >
> >> From: wa1zms at att.net
> >> Date: Sat, 11 Aug 2012 21:56:13 -0700
> >> To: time-nuts at febo.com
> >> Subject: [time-nuts] FRK specs.....
> >>
> >> I used to be of the opinion that the Efratom FRK-H was the best of the
> models of FRK Rb standards for both short-term stability and overall
> performance.
> >>
> >> Is that still true today?
> >>
> >> I know there are better solutions for short-term (BVA OCXO) and long
> term
> >> (Cs & MASERS). But where to things stack up today?
> >>
> >> I'm looking to buy an Rb that's better than my LPROs and other models.
> >> But I do not own an FRK-H.
> >>
> >> Looking for comments, please.
> >>
> >> Thanks in advance,
> >> -Brian, WA1ZMS
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