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So is the Tektronix 2465 scope.
I've been considering the idea of buying a Tek 2465B and had
found this link, earlier. Now that you bring this up to my
mind again, I'd like to post the link and some of the text
there:
http://www.tek.com/forum/viewtopic.php?f=5&t=4368
"I bought a 2465B (or so it appears) from a calibration
outfit in CA USA. The unit had fresh calibration.
Attempting to measure a signal in the 400MHz range, I
didn't like what I saw. I opened the case (again ;-)),
and noticed at the A1 PCB part number - 671-0720-08 -a
2445B PCB, not a 2465B PCB.
"I queried the seller, and this is what he claims:
'Tek made 2445B and 2465B with only one internal
difference: a 2445B has a bandwidth choke on the
backside of its main A1 board etched into the
printed circuitry of the bare board. This was
also true of the 2445A 2465A pair, and the
original 2445 2465 pair introduced in 1983.
'For the privilege of not having that bandpass
limiter, Tek charged clients $2000 more, but was
too lazy to make 2 really different scopes. So
since 1985, when I discovered Tek's laziness, I
have earned my living upgrading the 3rd digit
from 4 to 6.
'The clock stays with the A5 board. The 2445B A1
board, once it has its bandwidth choke bypassed
(I cut traces in 4 places on the back and spliced
in 2 short straight wires to carry the signals
from the DL100 delay line to the inputs of U600),
can do 400MHz.
'The only other difference is to ground a contact
(pin 23 J511) that tells the A5 processor board
that it is now has a 6 instead of a 4 (as 3rd
digit) that allows the 5nS/cm fastest sweep speed
to be accessible, instead of just going up to
10nS/cm.
'This is what many of my 2465B clients have, but
so far you are the only one to have noticed... '
"I looked at the circuits, and discovered a 3rd difference
- the 2465B PCB has inductor L403, apparently for
adjusting the HF circuit.
"Leaving aside the apparent legal ramifications of what
he has been doing for 25 years, without disclosing to
his customers, I would like to learn from the technical
people here:
"1. If there are any other technical differences between
the 2445B and 2465B A1 PCB's?
2. If the integrity of the A1 PCB has been compromised by
cutting the PCB traces?
3. If there is any spurious interference of any kind
caused by the new spliced wires?
4. If this modified 2445B A1 PCB is, in fact,
functionally equivalent to a real 671-0722-08 2465B A1
PCB (disregarding Tek's marketing considerations), and
if not, why not?"
Jon