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 <kb...@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 <k8yumdoo...@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 <kb...@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 <k8yumdoo...@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 <j...@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 (taproff...@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 > >>>> _______________________________________________ > >>>> time-nuts mailing list -- time-nuts@lists.febo.com > >>>> To unsubscribe, go to https://lists.febo.com/cgi-bin > >>>> /mailman/listinfo/time-nuts > >>>> and follow the instructions there. > >>>> > >>> _______________________________________________ > >>> time-nuts mailing list -- time-nuts@lists.febo.com > >>> To unsubscribe, go to https://lists.febo.com/cgi- > >> bin/mailman/listinfo/time-nuts > >>> and follow the instructions there. > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe, go to https://lists.febo.com/cgi- > >> bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.