[time-nuts] 5065A

John Miles jmiles at pop.net
Fri Sep 3 05:32:54 UTC 2010


It seems OK after replacing the silver-mica and feedthrough capacitors, and
reflowing all of the solder joints.  There were no jumps over 8 hours from a
cold start, and it had been glitching at least once per hour beforehand.

Corby, do you remember the loop filter values (and kVCO) you used for your
FTS 1200 replacement project that you mentioned awhile back?  This one
really needs a lower loop BW to keep from degrading its 10811-60109 below
10s.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of paul swed
> Sent: Thursday, September 02, 2010 6:35 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Maser manual (2)
>
>
> If the thing has a variable cap to tune the osc. My bet is thats
> the devil.
> In cheapy telco RBs they have given me lots of trouble.
>
> On Wed, Sep 1, 2010 at 11:40 PM, John Miles <jmiles at pop.net> wrote:
>
> > Good point -- I should swap out the feedthrough as well.  There
> is only one
> > in this case, for the power lead-in, but if it is growing
> internal whiskers
> > or otherwise failing I could see it causing this symptom...
> >
> > -- john, KE5FX
> >
> > > -----Original Message-----
> > > From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> > > Behalf Of Kit Scally
> > > Sent: Wednesday, September 01, 2010 8:34 PM
> > > To: time-nuts at febo.com
> > > Subject: [time-nuts] Maser manual (2)
> > >
> > >
> > > John,
> > >
> > > I'd put money on one of the feedthrough caps (easily damaged upon
> > > installation) in the Maser for such small jumps.
> > > >From memory, the 5065A uses SM components, but these could be guilty.
> > >
> > > I've learned many abstract things I'd never otherwise come across
> > > in this thread on home-built masers.  I for one would like to see
> > > more mileage on this topic although I'm not sure there's $25k in
> > > my "Xmas box" for the necessary parts to build one !
> > >
> > > Kit
> > > VK2LL
> > >
> > > >>>snip
> > > The 5065A is showing occasional phase jumps on the order of 10-100 ps
> > that
> > > coincide with small spikes in the current drawn by the lamp
> > > exciter, and I'm
> > > leaning towards blaming the silver-mica B-E feedback
> capacitor.  (It even
> > > has the same designation in both instruments' service manuals, C2.)
> > > Tom: this is why your BVA was appearing to jump when I
> measured it. :-P
> > >




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