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Failed O rings in these attenuators is a common problem as the equipment ages.? The material used to make them eventually dries out either from heat or environmental issues and becomes brittle thusly the O ring frequently crumbles and falls off.? This then causes either non-actuation of an attenuator stage or intermittent operation at best.

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We once tried to replace the O rings in an attenuator.? The first step was to measure a good item then try to find a replacement.? This required considerable disassembly of the attenuator then trying to find a O-ring that had not aged to the point where it was not wither brittle or its dimensions had changed.? Then the selection process continued.? At that point it was not? known what material the O rings were made out of.? I did hear from another engineer to be careful because some O rings will outgas affecting the contact reliability in the attenuator.? After randomly selecting a possibly suitable material the next step was to locate a small quantity of the O rings.? This resulted in eventually finding a manufacturer who would provide some samples instead of us having to buy hundreds of them to satisfy a minimum order.

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After all of this was done it was then decided that the total time and energy wasted I trying to “make do” by an in-house repair was far overshadowed by simply sending the attenuator to the repair agency which was the final outcome.

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The O rings are there for a reason mainly to cushion the blow of the solenoid when it actuates.

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Greg

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Greg?: The thing is I suspected an issue with the o-rings, but they’re all good. I’m pretty sure the issue is not mechanical.

However , I managed to break one of the plunger and I need to replace it when I first disassembled it. The upside is I am now very comfortable manipulating it.

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Next steps : find a plunger and bench the ATT correctly. I have a feeling my primary issue : AMPDT : ?GAIN FAIL is cause by something else.

I can get passed this error if I feed -17dB 300Mhz at the input. My CAL output is at around -18dB, which is also an issue.

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Why I targeted the ATT, is because the marker would read -45dB or more when the ATT was not set to a multiple of 20 (-20dB, -40dB)

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?

Failed O rings in these attenuators is a common problem as the equipment ages.? The material used to make them eventually dries out either from heat or environmental issues and becomes brittle thusly the O ring frequently crumbles and falls off.? This then causes either non-actuation of an attenuator stage or intermittent operation at best.

?

We once tried to replace the O rings in an attenuator.? The first step was to measure a good item then try to find a replacement.? This required considerable disassembly of the attenuator then trying to find a O-ring that had not aged to the point where it was not wither brittle or its dimensions had changed.? Then the selection process continued.? At that point it was not? known what material the O rings were made out of.? I did hear from another engineer to be careful because some O rings will outgas affecting the contact reliability in the attenuator.? After randomly selecting a possibly suitable material the next step was to locate a small quantity of the O rings.? This resulted in eventually finding a manufacturer who would provide some samples instead of us having to buy hundreds of them to satisfy a minimum order.

?

After all of this was done it was then decided that the total time and energy wasted I trying to “make do” by an in-house repair was far overshadowed by simply sending the attenuator to the repair agency which was the final outcome.

?

The O rings are there for a reason mainly to cushion the blow of the solenoid when it actuates.

?

Greg