Re: Spectrum Analyser TR4172
After adding the resistors, the VSWR ended up around 1.6:1 at 2.05GHz. Unfortunately, the iron melted a bit of the end of the input strip, so it's a couple mm shorter now than when I started. If anyone needs to know in the future, the iron was set to ~345C and it melted the strip. I knocked it down to 300 and worked quickly to do what I could do. A 0603 size resistor worked fine. I saw about 1.3:1 when I just pressed the resistor onto the trace. In the process of it all, part of the square loop came detached from the board, and I had to do the same glue technique to fix it. That whole input filter coupler is so fragile that I don't want to touch it again. I probably screwed it up a bit from doing this. I wish I could just scrap it and make or find a new filter, but I have no way of making this kind of a circuit board and chances of finding a replacement are of course quite unlikely.
Either tonight or tomorrow I will attempt to fix the regulator board, and hopefully it all will still work. It's getting quite ugly, as I just don't have the technique and equipment required for such intricate work. The board itself has such high thermal conductivity that it makes it difficult to find a balance between the temperature that won't melt the trace and a temperature that will be hot enough to still melt solder after the heat gets wicked from the tip from the board itself. It's just down right hateful.
I hope that all of this helps someone in the future looking to fix their sick TR4172.
Regards,
Matt
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