Hi Shawn,
Thank you for your reply. Indeed, it looks like something is wrong with the
TTL. It keeps reverting to 5V. Unfortunately for now, the question is moot.
The Synth board(s) no longer produce RF of any frequency and I have succumbed to
calling Agilent for a site visit. It may yet be a power supply problem that
I am ill equipped to detect much less fix.
Regards,
Scott
Scott K. Smith, Director of NMR Spectroscopy
The University of Texas at Austin | Chemistry | 832-294-1928 | utexas.edu
From: main_at_ammrl.groups.io <main_at_ammrl.groups.io> On Behalf Of Shawn Wagner
Sent: Wednesday, March 27, 2024 4:31 PM
To: main_at_ammrl.groups.io
Subject: Re: [AMMRL] MR400 LO switching
Hi Scott,
On the 400MR system the TTL line is low or 0V for selecting channel 1 (high
band) and 5V to select channel 2 (low band). If you have a problem passing
the high band (1H) you may want to check the TTL line to make sure that the
line drops to 0V, if it does not then the switch cannot pass the high band.
I just ran the TTL control to a scope and tuned on the manual tune, selected
either channel 1 or channel 2 to see the change in the output voltage. Please
note that the voltage on the TTL line stays at whatever the last setting was.
If that works fine, I would guess that the Mini Circuit switch is bad.
If you have a frequency synthesizer you could bench test the switch is a similar
manner.
Shawn
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Received on Tue Apr 02 2024 - 05:58:56 MST