Discussion:
TNS-BUF order update
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John Ackermann N8UR
2018-06-25 16:58:42 UTC
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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 (***@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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Van Horn, David
2018-06-25 17:19:05 UTC
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Parts availability is a bear at the moment.
It appears that the MLCC makers got tired of racing to see who could make the least money, and they are discontinuing tons of low profitable parts.
I have equivalents for most of my parts designated already, but we are having to reach into alternates for equivalents to get the parts we need.

Hopefully there's nothing too critical about that transistor and you can find a suitable sub.


-----Original Message-----
From: time-nuts <time-nuts-***@lists.febo.com> On Behalf Of John Ackermann N8UR
Sent: Monday, June 25, 2018 10:59 AM
To: Discussion of precise time and frequency measurement <time-***@febo.com>
Cc: TAPR Office <***@tapr.org>
Subject: [time-nuts] TNS-BUF order update

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 (***@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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Dana Whitlow
2018-06-25 20:56:20 UTC
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John,

Couldn't the TO-92 part (2N3904) be soldered down instead (if one has
steady hands),
and work about as well?

Dana
Post by John Ackermann N8UR
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,
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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John Ackermann N8UR
2018-06-25 21:04:14 UTC
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Possibly, but I don't know about power dissipation (the PZT has a heatsinking tab, and we run a fair bit of current through it.  And, that would be a hand-sokdering job that would run up the assembly cost.

We do have a source of the part, but we are stuck with the month or so delay.
Post by Dana Whitlow
John,
Couldn't the TO-92 part (2N3904) be soldered down instead (if one has
steady hands),
and work about as well?
Dana
Post by John Ackermann N8UR
We've had a delay due to parts availability -- a common transistor
(PZT3904) is apparently on worldwide back order with lead times
quoted of
Post by John Ackermann N8UR
up to a year. Our contract manufacturer has finally found a source,
but
Post by John Ackermann N8UR
they will not be delivered until mid-August. That means that TAPR
won't
Post by John Ackermann N8UR
receive the boards until the second half of September.
If the delay causes you a problem and you'd like to cancel your
order,
take
Post by John Ackermann N8UR
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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Bob kb8tq
2018-06-25 21:04:35 UTC
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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
Post by Dana Whitlow
John,
Couldn't the TO-92 part (2N3904) be soldered down instead (if one has
steady hands),
and work about as well?
Dana
Post by John Ackermann N8UR
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,
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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To unsubscribe, go to https://lists.febo.com/cgi-bin
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and follow the instructions there.
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Dana Whitlow
2018-06-25 22:39:47 UTC
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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
Post by Bob kb8tq
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
Post by Dana Whitlow
John,
Couldn't the TO-92 part (2N3904) be soldered down instead (if one has
steady hands),
and work about as well?
Dana
Post by John Ackermann N8UR
We've had a delay due to parts availability -- a common transistor
(PZT3904) is apparently on worldwide back order with lead times quoted
of
Post by Dana Whitlow
Post by John Ackermann N8UR
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,
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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Post by Dana Whitlow
and follow the instructions there.
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Bob kb8tq
2018-06-25 23:19:05 UTC
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Hi

If it’s used in a grounded base configuration, it does indeed matter …..

Bob
Post by Dana Whitlow
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
Post by Bob kb8tq
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
Post by Dana Whitlow
John,
Couldn't the TO-92 part (2N3904) be soldered down instead (if one has
steady hands),
and work about as well?
Dana
Post by John Ackermann N8UR
We've had a delay due to parts availability -- a common transistor
(PZT3904) is apparently on worldwide back order with lead times quoted
of
Post by Dana Whitlow
Post by John Ackermann N8UR
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,
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
_______________________________________________
To unsubscribe, go to https://lists.febo.com/cgi-bin
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Post by Dana Whitlow
and follow the instructions there.
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Bruce Griffiths
2018-06-25 23:25:37 UTC
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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
Post by Bob kb8tq
Hi
If it’s used in a grounded base configuration, it does indeed matter …..
Bob
Post by Dana Whitlow
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
Post by Bob kb8tq
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
Post by Dana Whitlow
John,
Couldn't the TO-92 part (2N3904) be soldered down instead (if one has
steady hands),
and work about as well?
Dana
Post by John Ackermann N8UR
We've had a delay due to parts availability -- a common transistor
(PZT3904) is apparently on worldwide back order with lead times quoted
of
Post by Dana Whitlow
Post by John Ackermann N8UR
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,
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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Post by Dana Whitlow
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Gerhard Hoffmann
2018-06-25 23:48:56 UTC
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Am 26.06.2018 um 01:19 schrieb Bob kb8tq
Post by Bob kb8tq
If it’s used in a grounded base configuration, it does indeed matter …..
It is not.

I have a cut tape of 10 still in the Mouser bag
because of their guaranteed beta of only 30 @ 100 mA.
I'd be willing to give them away if it makes someone happy.
But that would be just enough for 3 1/3  amplifiers.

regards, Gerhard

( I love those BJTs made by Zetex / Diodes, Inc for their low Rbb.
I have got 50 pV/rt Hz voltage noise  for 16 of them in par in a
baseband amplifier.)
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