Re: 7A29 attenuator fault corrosion issue


Adrian
 

Hi George,

Glad it worked for you too! I guess you may have figured this out as well but when it comes to re-engaging the slots in the SMA connector with the stripline I found the springy stripline position seemed to be offset from centre a bit. I assume this is to ensure good contact with the slot in the pin.

I found that by leaving the screws holding the top plate slightly loose and angling the SMA plate a small amount away from the bottom plate it was possible to use the SMA plate to push down on the top plate a tiny amount and still just see (with a good light!) the end of the stripline and the slot to align them and then 'hinge' the SMA plate into position before tightening the top plate fully.

As to what caused the problem my guess is that the corrosion is galvanic in nature as it was very local to the contact area of the resistor ground connection. I couldn't figure out what that contact 'lip' was made from though - I thought it looked like some sort of elastomer in color but on mine at least it seemed pretty hard for that?

I notice there's I guy selling a dozen or so 7A29s on the 'bay tonight - 60 bucks each or offers, would be a good deal if I wasn't on the wrong side of the Atlantic these days! he has them all listed as 'TA29' for some (typographical?) reason.

Adrian

On 7/20/2018 12:53 PM, glkinst@... wrote:
As you mentioned, it is really important to remove the SMA connectors first before removing of the bottom plastic plate that has the gold-plated fingers and tabs. The tabs fit in the slot on the SMA connector. Re-assembly requires patience, don't force for it or you will damage the connection.

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