[time-nuts] Austron 1150 Oscillator - Repair and Wrong Pinout
skip.withrow at gmail.com
Fri Mar 10 15:56:09 EST 2017
I recently came across an Austron 2010B Disciplined Oscillator at a hamfest
and couldn't pass it up. It was billed as working, but I figured the 1150
oscillator inside the unit was worth what I paid for it if nothing else.
Thank you Ruslan for the help with the manual. So I proceeded to fire the
unit up, and one of the first steps is to put the internal 1150 oscillator
on frequency. Which, of course, wasn't going to happen. The trimmer was
backed all the way out and it was still quite a ways off.
So, time to open up the can of the 1150 and tinker. The 1150 is a nice
oven controlled oscillator inside a glass dewar and is on 5MHz (this
oscillator may have been made for Austron by Sulzer, or is a Sulzer design
manufactured by Austron). I found a 10pF pad across the trimmer so removed
that, semi assembled it, and fired it up. After a reasonable amount of
warmup time the trimmer put the oscillator on frequency (yeah, or so I
thought). After a few minutes it was off in the weeds again. It just
wouldn't seem to stay on frequency.
At about this point I decided to hook up the EFC and see if this made a
difference. I had a copy of the 1150 data sheet, but the EFC pins listed
didn't seem to match the hardware. I double checked with the 2010B wiring,
and indeed the EFC is on pins 8 and 9 (the data sheet says 7 and 8). This
led me to completely reverse engineer the 1150 schematic to check the EFC
operation and oscillator operation.
To make a VERY long story shorter, I discovered the root of my problem was
with the oven controller. The heater control transistor wasn't shorted or
open, but wasn't a transistor either. It would not shut off completely
when commanded (very leaky I guess). The oven was slowly rising above the
setpoint, but wasn't running balls to the wall either. This was the root
of my continual drift. After replacing the transistor all is well,
temperature is stable very near 70C, and the oscillator is well behaved and
Bottom line is -
1. The 1150 data sheet and pinout that I have seen on the net is WRONG.
Pin 7 is the Oven Monitor, pin 8 is EFC (-), and pin 9 is EFC (+). My 1150
part number is 30294320.
2. I have a complete set of schematics, pictures of the inside of the unit,
and data sheet. I'm very willing to share and hope to get a package
together to upload to KO4BB.com, in the meantime if you need information
feel free to contact me.
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