[G0HZU_JMR]

Hi Brian
I'm very busy over this weekend but I'll try and find time to post up some info. However, what you must NOT do is open up the first IF module (that sits under the mixer box) and touch any of the PCB traces. Especially around the IF amplifier section where there are some little blocks of absorber stuck to the PCB.

I found the same issue with softened copper traces that I found in the attenuator section and I think the glue they used to hold down the RF absorber ages or cures badly in terms of becoming a chemical hazard.

On my IF1 unit this glue had attacked one of the printed bias resistors in the active (16mA) bias circuit to the IF amplifier and slowly eroded it. The effect was that the resistor suddenly went up in value a lot and the IF amplifier lost its power supply. The module still biased it at 16mA but the voltage at the amplifier was down at about 200mV!

Also, I think this glue has caused accelerated ageing/corrosion to the fasteners and connections in the IF1 module. They go VERY rusty like they have been underwater for a few years. Also, the connections from the SMA launchers to the PCB are done with tiny ribbons of gold? metal and the connection to the SMA centre can corrode here (the SMA centre corrodes rather than the gold ribbon) and this can break the connection or make it unreliable. There's no other corrosion like this anywhere else in either of my analysers so I blame the glue...

The good news is that the IF amplifier device survived in my analysers and you just need to solder in a SMD resistor in place of the printed resistor if yours has the same fault as mine.

But the copper microstrip on this PCB seems to go very soft. Almost like rotten paint on a car. So if you touch it or try and scrape any residues from it, it will lift up and fall to pieces like it is thousands of years old!

So the fix is easy but you have to do the whole thing like it was surgery in an operating theatre because one slip means the copper traces are gone... They can't be stuck down again like regular copper tracks because they seem to go very soft and fall apart.

I doubt that your mixer will be damaged but I did find the original manufacturer's part number for it and I think they are still available online (but not from Advantest)

i.e. this is not an Advantest part number but the real part number for the diode ring.

It's a VERY strong mixer with 8 diodes inside and the LO drive level is about +23dBm so you may be OK and your mixer will be healthy.

I'll dig out my documentation and post up the part number and a few internal pictures when I get a chance.