[time-nuts] HP 10811 update

paul swed paulswedb at gmail.com
Thu Jul 25 09:12:38 EDT 2013


I totally agree that a 123 will not replace it. A luck would have it I have
12 X 2n3390 xsistors Beta 400-1000. These are the older TO-98s and I will
try one tonight.
Regards
Paul
WB8TSL


On Thu, Jul 25, 2013 at 12:00 AM, Orin Eman <orin.eman at gmail.com> wrote:

> I find it hard to believe that NTE spec the 123AP to replace a transistor
> with min beta of 500...
>
> This is quite entertaining:
>
> http://www.vetco.net/catalog/product_info.php?products_id=1856
>
> Look at the parts it's supposed to replace.
>
> (Nothing against Vetco - they are a great source of NTE components and are
> local to me.  They are just quoting what NTE claim.)
>
> Orin.
>
>
>
>
> On Wed, Jul 24, 2013 at 8:42 PM, J. L. Trantham <jltran at att.net> wrote:
>
> > The 2N6429 crosses to an NTE123AP, in stock at Allied for $0.80.
> >
> >
> >
> http://www.alliedelec.com/search/productdetail.aspx?SKU=70214870&mkwid=szEc5
> >
> >
> jMBI&pcrid=23468365337&pkw=nte123ap&pmt=e&pdv=c&gclid=CKyzu9_cybgCFWYV7AodJA
> > sAWQ
> >
> > Good luck.
> >
> > Joe
> >
> > -----Original Message-----
> > From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> > Behalf Of paul swed
> > Sent: Wednesday, July 24, 2013 8:29 PM
> > To: Discussion of precise time and frequency measurement
> > Subject: Re: [time-nuts] HP 10811 update
> >
> > Well learned quite a bit Q4 does have an issue. Further there is a reason
> > it
> > has such high Beta. Its must deliver 30 ma to the oscillator and buffer.
> > I was quite surprised by this current level. I was  guessing the
> oscillator
> > was a few mils and the buffer maybe 8.
> > The 2n3904 simply does not cut it. Need to do some digging in the ole
> > transistors.
> > Regards
> > Paul.
> >
> >
> > On Wed, Jul 24, 2013 at 8:06 PM, paul swed <paulswedb at gmail.com> wrote:
> >
> > > I can hope
> > > I will embed a k thermocouple also.
> > >
> > >
> > > On Wed, Jul 24, 2013 at 7:45 PM, Bob Camp <lists at rtty.us> wrote:
> > >
> > >> Hi
> > >>
> > >> The regulator should be fixed, and the OCXO will work better with it
> > >> repaired. That said, shifting the regulated voltage from 5.7 to 5.27
> > >> volts should not shift that oscillator 45 Hz.
> > >>
> > >> Bob
> > >>
> > >> On Jul 24, 2013, at 9:00 AM, paul swed <paulswedb at gmail.com> wrote:
> > >>
> > >> > Hello to the group. Numbers of threads running on the HP 10811.
> > >> > Mine is
> > >> 45
> > >> > Hz low. The oven is most likely ok. I did get the can open per the
> > >> various
> > >> > other threads and the web pix. Started testing the circuits and
> > >> > have
> > >> found
> > >> > that the regulator for the oscillator isn't. Its supposed to
> > >> > produce
> > >> 5.7V
> > >> > and is at 5.27V thats pretty significant. The transistor looks like
> > >> > a shorted collector base junction. Though I do not have it out of
> > >> > circuit yet. Its Q4 a 2n6429. What interesting about this
> > >> > transistor is its
> > >> beta at
> > >> > 1 ma is 500 min and max is 1300. Its not a darlington. Thats pretty
> > >> > amazing. I am looking through my xsistors to find something close.
> > >> > May
> > >> just
> > >> > through a 2n3904 in for a quick test. Its beta is nothing like the
> > 6429.
> > >> > But it would help to prove/disprove the point that the low V may be
> > >> > offsetting the oscillator I hope.
> > >> > Will also embed a K thermal couple to verify the oven really is in
> > >> > the 80-84C region.
> > >> > Regards
> > >> > Paul.
> > >> > WB8TSL
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