Noisy Sulzer 2.5 - Suggestions?
I picked up a Sulzer 2.5 (not 2.5A or 2.5B or 2.5C) oscillator and 5P
power supply. It's working, but the AlDev at low tau is poor. After a
few days of operation the AlDev @ 1sec. is only 1e-10. It's not the
power supply. I'm running under 'AC fail' conditions with a lab power
supply standing in for the batteries. This bypasses almost everything
in the power supply. Eventually, I plan to replace the batteries with
lead-acid and replace the circuit board with an improved circuit.
So, I'll be opening up the oscillator to see what's what. My first
'usual suspect' will be the Ta capacitors, but I'm wondering about all
those carbon composition resistors. Should I be looking at a wholesale
replacement with metal film? Maybe just in the oscillator and AVC
areas? Are there any other known trouble spots with these oscillators?
I haven't been able to find any info on the 2.5. The manuals and
schematics for the 5A and the 2.5B/C are some help, but the 2.5 is very
different from the 2.5B/C. Any info would be greatly appreciated.
Thanks,
Ed
Hi
Let it run for a month before you worry much about measuring what it is doing ….
Some (but not all) of those old crystals took a while to settle in.
Bob
On Aug 17, 2016, at 4:25 PM, Ed Palmer ed_palmer@sasktel.net wrote:
I picked up a Sulzer 2.5 (not 2.5A or 2.5B or 2.5C) oscillator and 5P power supply. It's working, but the AlDev at low tau is poor. After a few days of operation the AlDev @ 1sec. is only 1e-10. It's not the power supply. I'm running under 'AC fail' conditions with a lab power supply standing in for the batteries. This bypasses almost everything in the power supply. Eventually, I plan to replace the batteries with lead-acid and replace the circuit board with an improved circuit.
So, I'll be opening up the oscillator to see what's what. My first 'usual suspect' will be the Ta capacitors, but I'm wondering about all those carbon composition resistors. Should I be looking at a wholesale replacement with metal film? Maybe just in the oscillator and AVC areas? Are there any other known trouble spots with these oscillators?
I haven't been able to find any info on the 2.5. The manuals and schematics for the 5A and the 2.5B/C are some help, but the 2.5 is very different from the 2.5B/C. Any info would be greatly appreciated.
Thanks,
Ed
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Ed,
Thats quite the challenge and yes the carbon resistors must be about 50
years old now. So questioning them is reasonable. I have a c so take my
next comment with caution.
The oscillator is a small circuit and then it runs to buffers and
multipliers and stuff.
Lots of parts of every type. Maybe it makes sense to isolate and measure
just the oscillator circuit to see how it behaves without all of the other
stuff. Also there were various regulators in that can. Lots of
possibilities for trouble. But also worth the effort to figure it out.
Great old oscillators.
Regards
Paul
WB8TSL
On Wed, Aug 17, 2016 at 4:25 PM, Ed Palmer ed_palmer@sasktel.net wrote:
I picked up a Sulzer 2.5 (not 2.5A or 2.5B or 2.5C) oscillator and 5P
power supply. It's working, but the AlDev at low tau is poor. After a few
days of operation the AlDev @ 1sec. is only 1e-10. It's not the power
supply. I'm running under 'AC fail' conditions with a lab power supply
standing in for the batteries. This bypasses almost everything in the
power supply. Eventually, I plan to replace the batteries with lead-acid
and replace the circuit board with an improved circuit.
So, I'll be opening up the oscillator to see what's what. My first 'usual
suspect' will be the Ta capacitors, but I'm wondering about all those
carbon composition resistors. Should I be looking at a wholesale
replacement with metal film? Maybe just in the oscillator and AVC areas?
Are there any other known trouble spots with these oscillators?
I haven't been able to find any info on the 2.5. The manuals and
schematics for the 5A and the 2.5B/C are some help, but the 2.5 is very
different from the 2.5B/C. Any info would be greatly appreciated.
Thanks,
Ed
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ailman/listinfo/time-nuts
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My old 2.5A was acting up in strange drifty ways. I opened the oven, and found
that all of the white cube shaped ceramic capacitors in the oscillator were covered
with fuzz on the electrode ends. I am guessing that they were growing a great
tin whisker beard. I cleaned it all off, and performance improved greatly.
-Chuck Harris
Ed Palmer wrote:
I picked up a Sulzer 2.5 (not 2.5A or 2.5B or 2.5C) oscillator and 5P power supply.
It's working, but the AlDev at low tau is poor. After a few days of operation the
AlDev @ 1sec. is only 1e-10. It's not the power supply. I'm running under 'AC fail'
conditions with a lab power supply standing in for the batteries. This bypasses
almost everything in the power supply. Eventually, I plan to replace the batteries
with lead-acid and replace the circuit board with an improved circuit.
So, I'll be opening up the oscillator to see what's what. My first 'usual suspect'
will be the Ta capacitors, but I'm wondering about all those carbon composition
resistors. Should I be looking at a wholesale replacement with metal film? Maybe
just in the oscillator and AVC areas? Are there any other known trouble spots with
these oscillators?
I haven't been able to find any info on the 2.5. The manuals and schematics for the
5A and the 2.5B/C are some help, but the 2.5 is very different from the 2.5B/C. Any
info would be greatly appreciated.
Thanks,
Ed
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.