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Old 15th Jul 2022, 3:30 pm   #187
Matt kd4pbs
Tetrode
 
Join Date: Mar 2021
Location: Raleigh, North Carolina, USA.
Posts: 62
Default Re: Spectrum Analyser TR4172

Can't help you there, Alan. I noticed the same thing with the insanely difficult to solder properties of the substrate, and with my iron at a heat setting that would overcome the thermal conduction from the board, it would melt the traces.
I think I do remember having the same issue that you see... the directional coupler/filter not being equally terminated.
Ultimately, after bodging the SA enough that I got it working and calibrated, after a few weeks I noticed it went deaf again. Likely a leg of the mixer corroded again. I have since pulled it from the shelf and set it in the morgue awaiting either the day it gets carted to the dump or I find the required parts to make it right.
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