[time-nuts] FRK specs.....
EWKehren at aol.com
EWKehren at aol.com
Sun Aug 12 12:13:14 EDT 2012
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
In a message dated 8/12/2012 8:09:54 A.M. Eastern Daylight Time,
wa1zms at att.net writes:
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.
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
>> Is that still true today?
>> I know there are better solutions for short-term (BVA OCXO) and long
>> (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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