Hi Morris,
i have copied the manual for the 5100A,
except the parts list, which was missing in my
copy, too. I send it tomorrow.
With that, i send you two BA243S Switching Diodes
which snaps well. But compared to a "true"
HP-SRD (My spare for the Clock-Circuit in my 5360A)
it has about half the spike-voltage, but still a lot
more than some other switching and tuning diodes.
If you have any junk tv-tuner, best from the mid 70's
(pre PLL-Age),
pull out all diodes and test them, maybe you find a good working
one before my arrives.
Maybe you have to fiddle with the bias voltage (resistor), too.
Most other diodes doesn't snap either.
Maybe the pulse is too low for the following stages?
Or the driving power is too low? The snappys want power!
And they can widhstand a lot! Don't be shy! ;-)
I will measure the pulse voltage and some
other interesting voltages in that stage in our 5110A,
but not before Wednesday of the next week, due to
our pentecost-weekend fieldday which starts tomorrow,
and i have a lot to organize this day and tomorrow
and still after the FD. ...Dry the tents, repair the generator,
... and so on :-(
;-)
Jorgen
dj0ud
--- In hp_agilent_equipment@..., "morriso2002"
<morriso@v...> wrote:
Hi all,
I have been working on a 5110A synth driver with a problem of no
output. After getting a manual I diagnosed a failure of the Step
Recovery Diode in the harmonic generator and sure 'nough, it's open
circuited. (Why is it always these rare parts that fail - SRDs,
tunnel diodes , avalanche transistors...Murphy's list goes on and
on...)
Following advice on this list, I tried several diodes using clip-
leads. I was able to get nice spikes from a couple of different low
freq tuning diodes but still no output from succeeding stages.
The best result is with an unlabelled miniature tuning diode which
gives positive going spikes 30 nS wide and 1 volt in amplitude at
the
cathode of the diode. These parameters would improve further if the
diode was properly mounted on the PCB. After passing through the HP
filter network however there is nothing visible at the emitter of
the
pulse amplifier transistor and no output. The transistor is a zero
biased common base connected 2N1143 which is a Ge pnp with a Ft of
200 MHz - another unobtainable Murphy favourite :-( Removing it for
testing requires messy surgery.
Any ideas? Have any of the mavens here actually measured the pulse
parameters in this circuit? Is the transistor faulty or is there
just
not enough drive to the amplifier? Unfortunately the manual is
silent
on the subject.
On the bright side, I'm learning a lot (small consolation).
Any help appreciated,
Morris
