[time-nuts] Wenzel Oscillator Repair

John Miles jmiles at pop.net
Tue Jan 20 12:28:31 EST 2009


You probably have a lot more room to play with, given the larger housing on
your OCXO.  The ULN series is rather densely packaged, and that was one
reason why I wasn't crazy about going after it with a propane torch.  In
your case I'd be tempted to try the torch method before actually damaging
the housing with a Dremel tool.

While fixing a couple of Ovenaire OCXOs that use a similar form factor, I've
noticed that their PC board edges don't come anywhere near the endcap.  The
Ovenaire parts were sealed with epoxy, so a heat gun was all that was needed
to open them, but I'm sure I could've opened them with a torch without
hurting anything, if they'd been soldered shut.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Ed Palmer
> Sent: Tuesday, January 20, 2009 5:59 AM
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Wenzel Oscillator Repair
>
>
> Now I understand!  I was planning to reuse the case.  It didn't occur to
> me to sacrifice the case and put the oscillator in another box.
>
> Thanks for the idea, John.
>
> Ed
>
> > Message: 3
> > Date: Mon, 19 Jan 2009 21:20:54 -0800
> > From: "John Miles" <jmiles at pop.net>
> > Subject: Re: [time-nuts] Wenzel Oscillator Repair
> > To: "Discussion of precise time and frequency measurement"
> > 	<time-nuts at febo.com>
> > Message-ID: <PKEGJHPHLLBACEOICCBJMECCBCAC.jmiles at pop.net>
> > Content-Type: text/plain; charset="us-ascii"
> >
> > I used a fiberglass-reinforced cutoff wheel.  This can open practically
> > anything, but it puts a lot of vibration and dust into the innards of
> > whatever you're taking apart.  My guess was that this was safer
> than using a
> > torch.
> >
> > Since I wasn't going to be able to maintain the original hermeticity, I
> > remounted the oscillator in a Hammond box, like so:
> >
> > http://www.thegleam.com/ke5fx/w1.jpg
> >
> > I brought the trimmer (which was also damaged in this
> particular oscillator)
> > and oven-status LED out to the box lid, along with the four original
> > terminals.  Makes a nice package that can be easily opened for
> maintenance:
> >
> > http://www.thegleam.com/ke5fx/w2.jpg
> >
> > The repackaged OCXO seems to work fine.  I haven't made any hardcore
> > measurements with it but I can tell just by watching the
> counter that its
> > short-term stability is similar to my other unmolested 5 MHz ULN.
> >
> > -- john, KE5FX
> >
> >> -----Original Message-----
> >> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> >> Behalf Of Ed Palmer
> >> Sent: Monday, January 19, 2009 4:07 PM
> >> To: time-nuts at febo.com
> >> Subject: Re: [time-nuts] Wenzel Oscillator Repair
> >>
> >>
> >> I hadn't thought of using a Dremel.  Did you use an abrasive wheel or a
> >> steel cutter?  The case on mine looks to be about 20 ga. tin-plated
> >> steel (~0.04" thick).  The gap is so small it might have been
> a friction
> >> fit to start with.
> >>
> >> Ed
> >>
> >>> From: "John Miles" <jmiles at pop.net>
> >>> Subject: Re: [time-nuts] Wenzel Oscillator Repair
> >>> To: "Discussion of precise time and frequency measurement"
> >>> 	<time-nuts at febo.com>
> >>> Message-ID: <PKEGJHPHLLBACEOICCBJMEPMBBAC.jmiles at pop.net>
> >>> Content-Type: text/plain; charset="us-ascii"
> >>>
> >>> I had a similar problem with a 5 MHz OCXO from their ULN
> >>>
> >> series.  There was
> >>
> >>> a bad solder joint on the output connection, easy enough to fix
> >>>
> >> once I got
> >>
> >>> the unit open.
> >>>
> >>> In my case I used a Dremel tool to cut the seam.  Suggest
> wearing a dust
> >>> mask, obviously, and keep your cuts close to the perimeter of
> >>>
> >> the can, in
> >>
> >>> case the PC board comes right up to the edge like mine did.
> >>>
> >>> -- john, KE5FX
> >>>
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