[time-nuts] FE-5680A Mechanical Question

Bob Camp lists at rtty.us
Fri Jan 13 12:26:09 EST 2012


Hi

Bert's Rb is performing better than it has any right to perform. He got
lucky.

At least that's my claim until I get a few measured here. Could be wrong...

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of J. L. Trantham
Sent: Thursday, January 12, 2012 8:54 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] FE-5680A Mechanical Question

Bob,

You (and others) make a good point.  The stability of a good Rb may be such
that, in a portable operation, if you are going to be there for less than 2
weeks, why bother with the GPSDRbO option.  Turn it on, adjust it to your
GPSDO at home, turn it off, take it to the site, turn it on, use it, turn it
off, bring it back home, turn it on and compare it to your GPSDO.

I guess we'll have to wait for the 'aging' measurements from Bert and others
to know the answer to this.

Bert's initial measurement from his sounds like it is unlikely that we'll be
able to improve very much from that, assuming all units perform similarly.

Joe


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bob Camp
Sent: Thursday, January 12, 2012 11:40 AM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] FE-5680A Mechanical Question

Hi

With the Rb pulling about 700 ma at 15 volts, it's going to nuke a battery
pretty fast. You may find that (unlike an OCXO) the Rb comes back up to
frequency fairly quickly (minutes /hours not days / weeks). Simply
unplugging it and carrying it power off could be workable approach. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of J. L. Trantham
Sent: Wednesday, January 11, 2012 11:56 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] FE-5680A Mechanical Question

Bill, Brian, Bill, and Peter,

Thanks for the info.  All I need now is a 'project' to incorporate the unit
into.

In the back of my mind, I have the thought of a 'box' that will be battery
powered or 110 VAC powered (perhaps with an internal SLA battery) and
include a GPSDO and Rb unit (possibly a GPSDRbO) for the purpose of a
'reference' for portable operation in the microwave regions.

Ah!!!!  Dreaming!  Makes looking forward to retiring very attractive!

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Peter Bell
Sent: Wednesday, January 11, 2012 10:28 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FE-5680A Mechanical Question

The pot accessible through the hole in the casing appears is the fine
frequency adjust pot on the older units - on these, it's connected to
an ADC input, but as far as I can see adjusting it does nothing at
all.

There are two screws hidden under the labels that hold the top over on
- you also need to remove the two small screws on the side that bolt
the D-type mounting bracket in place.

Regards,

Pete Bell


On Thu, Jan 12, 2012 at 10:33 AM, J. L. Trantham <jltran at att.net> wrote:
> Boy!!!!!!!  I would have 'screwed' that up!
>
> Bill was correct.  Mine were 1/16th inch Allen screws, not Torx as Brian
> has, and were very easily removed.  They appear to be 3mm dia. X 5mm long
> with a 0.5mm pitch screw, in spite of having a 1/16th inch hex opening.
>
> There were two Phillips head screws underneath that appear to hold the
> bottom cover in place.
>
> On another topic, there is a small opening on the side (near the
> 'FE'Trademark) with what appears to be a multi-turn pot inside.  What is
> that?
>
> Also, the 'sticker' on the top, that includes the 'FE' Trademark,
> 'FE-5680A', etc., has a 'soft spot' on the bottom edge.  In addition,
there
> is a 'soft spot' under the 'sticker' at the bottom of the front, near the
> connector, and includes the serial number.  Does anyone know what is under
> these 'stickers'?
>
> Thanks again.
>
> Joe
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Brian, WA1ZMS
> Sent: Wednesday, January 11, 2012 8:52 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] FE-5680A Mechanical Question
>
> My "rivets" were tiny Torx screws.
>
>
> -Brian, WA1ZMS
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of J. L. Trantham
> Sent: Wednesday, January 11, 2012 9:22 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] FE-5680A Mechanical Question
>
> Should I ever have time to pursue the Rb unit, what happens when I 'drill
> out' all the rivets that mount the unit to the PCB that it arrived on?
 Any
> reason to keep it on the PCB?
>
>
>
> Does the bottom cover come off?  Will I need to replace the rivets with
> something else to keep the bottom cover on?
>
>
>
> Thanks in advance.
>
>
>
> Joe
>
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