[time-nuts] TNS-BUF order update

Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Jun 25 19:25:37 EDT 2018


Its a form  of CE with a resistor in series with the emitter coupled with transformer feedback from collector to base.
Production scheduling likely prevents substitution of alternatives to achieve a faster delivery.
Assembly costs would likely increase if leaded parts are substituted.

Initial breadboards of a single amplifier stage used leaded components for convenience.

Bruce

> On 26 June 2018 at 11:19 Bob kb8tq <kb8tq at n1k.org> wrote:
> 
> 
> Hi
> 
> If it’s used in a grounded base configuration, it does indeed matter …..
> 
> Bob
> 
> > On Jun 25, 2018, at 6:39 PM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> > 
> > John speaks of high dissipation, which is a good point.  However, I doubt
> > that the
> > lead inductance will be a noticeable factor at 10 MHz unless a leaded part
> > is
> > mounted sloppily.
> > 
> > Dana
> > 
> > 
> > On Mon, Jun 25, 2018 at 4:04 PM, Bob kb8tq <kb8tq at n1k.org> wrote:
> > 
> >> Hi
> >> 
> >> The PZT version actually has a higher power dissipation than the leaded
> >> part. It
> >> also does a bit better at RF frequencies due to lower lead inductances.
> >> Not having
> >> the schematic in front of me, I don’t know if either one is a real big
> >> deal in this case.
> >> It has been on other circuits I’ve used them in.
> >> 
> >> Bob
> >> 
> >>> On Jun 25, 2018, at 4:56 PM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> >>> 
> >>> John,
> >>> 
> >>> Couldn't the TO-92 part (2N3904) be soldered down instead (if one has
> >>> steady hands),
> >>> and work about as well?
> >>> 
> >>> Dana
> >>> 
> >>> 
> >>> On Mon, Jun 25, 2018 at 11:58 AM, John Ackermann N8UR <jra at febo.com>
> >> wrote:
> >>> 
> >>>> To those who pre-ordered TNS-BUF boards:
> >>>> 
> >>>> We've had a delay due to parts availability -- a common transistor
> >>>> (PZT3904) is apparently on worldwide back order with lead times quoted
> >> of
> >>>> up to a year.  Our contract manufacturer has finally found a source, but
> >>>> they will not be delivered until mid-August.  That means that TAPR won't
> >>>> receive the boards until the second half of September.
> >>>> 
> >>>> If the delay causes you a problem and you'd like to cancel your order,
> >>>> please contact the TAPR office (taproffice at tapr.org) and John will take
> >>>> care of that (though he will be out of town until July 6).
> >>>> 
> >>>> Sorry for the inconvenience, but we did not want to risk using a
> >>>> substitute component that might change the performance of the unit.
> >>>> 
> >>>> John
> >>>> _______________________________________________
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> >>>> 
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