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Matt kd4pbs · 17th Mar 2021, 12:07 am

If it's working, I think leaving it alone is a good idea. Mine suddenly went to about 40+dB deaf, and that was from the lead finally giving away. I had to literally scrape away some of the black epoxy (NOT the same stuff as what's on the 1st IF Amp!) to expose enough metal to be able to solder to it. It was NOT at all a fun job!
This mixer does indeed seem to be unobtanium. I made an inquiry with a company in the states about getting one from them and after I answered all their questions to satisfy them I wasn't building a thermonuclear detonator, they ghosted me.
Looking through my 1st mixer input attenuator, the two shunts measure 147.44Ω and 147.9Ω, and the series reads 16.325Ω. As Jeremy pointed out, that's about right for a 3dB pi attenuator. Odd that yours is much higher. I wonder if it got toasted?
I am digging for the 1.84G post-filter connection with my NRP18T at the ready... Hopefully I will be able to find a convenient spot to ready this.

17th Mar 2021, 12:07 am	#127
Matt kd4pbs Tetrode Join Date: Mar 2021 Location: Raleigh, North Carolina, USA. Posts: 62	Re: Spectrum Analyser TR4172 If it's working, I think leaving it alone is a good idea. Mine suddenly went to about 40+dB deaf, and that was from the lead finally giving away. I had to literally scrape away some of the black epoxy (NOT the same stuff as what's on the 1st IF Amp!) to expose enough metal to be able to solder to it. It was NOT at all a fun job! This mixer does indeed seem to be unobtanium. I made an inquiry with a company in the states about getting one from them and after I answered all their questions to satisfy them I wasn't building a thermonuclear detonator, they ghosted me. Looking through my 1st mixer input attenuator, the two shunts measure 147.44Ω and 147.9Ω, and the series reads 16.325Ω. As Jeremy pointed out, that's about right for a 3dB pi attenuator. Odd that yours is much higher. I wonder if it got toasted? I am digging for the 1.84G post-filter connection with my NRP18T at the ready... Hopefully I will be able to find a convenient spot to ready this.