Hi Rainer,
I'd be a bit surprised if this were the result of "switching one bit" as you
mention below but I have another guess. My guess would be that when
you started atmm the first thing it did was set the motors to some previously
defined initial position. So that when it finally showed the tuning dip
it was reasonably well tuned. Perhaps the system had been disconnected
or power cycled at some point in the past and when the probe was tuned after
that it initialized all the motors (including 2H tune and match) and left
them in some odd position.
Anyway, that's my guess. If you'd done wobb before atmm you could have
checked this but either way, as long as it's running, I'm happy.
Cheers,Mike
On Monday, October 7, 2024 at 01:22:13 PM MDT, Platz Hirsch wrote:
Hello,
many thanks for all responses, especially those of Clemens Anklin, Bernd Simon
and Michael Groves.
Problem: This was a 500 MHz machine with cryoprobe and AVIII console. Lock
receiver seemed to be fine, but to get a reasonable signal a very strong lock
power signal was necessary. Measurements told, that the lock output signal was
fine until the input connector of the cryo probe.
Solution:
Load parameter set gradshim1d2h and start atmm. Stop atmm without any other action.
Return to normal operation.
That's all. Althouh our issue is perfectly solved, I am very curious, what is going
on behind the scene. Apparently the action described above switches one bit. But
what's the action of that change? I was able to follow the lock transmitter signal
until the connector of the cryo probe. The amplitude of the signal was correct and
there was the bias signal to drive the built in T/R switch. In spite of high lock
power used, there was no sign of saturation of the deuterium signal, the lock power
became lost anywhere. And I didn't change tuning/matching to get normal operation back.
From my point of view I have only one weak idea. The 5V bias signal seems to be weak.
Maybe there is a built in amplifier to increase that signal. At least, this happens
within the HPPR preamplifiers. And maybe the action described above, switched on the
power of this bias amplifier? I wasn't able to find any detailed electrical scheme.
Bernd Simon told me, that UniTool no longer is able to enable/disable the cryo preamplifiers.
This action requires to edit parameter files manually. Many thanks for a sample file.
Many thanks again
Rainer
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Received on Mon Oct 07 2024 - 12:26:41 MST