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I have an HP 905A sliding load which is complete with all of the interchangeable pins and bodies for male/female N and APC7, but there's a warning about never mating the connector pins with a Precision-N male.? Is there a spec like MIL-C-39012C for Precision N? That spec has the standard dimensions for checking pin offset, and runout, but the most recent 1994 version doesn't mention Precision-N.?? Is that MIL-C spec the canonical spec for N connectors, or is there a higher authority that defines the tolerance and dimensions and includes the Precision-N specs?

The manual says I can use IPA to clean the connector bodies (which have the usual greenish decomposed foam guck on them) but nothing like Acetone or other solvents. I'm wondering if a gentle thrash in a warm ultrasonic bath of distilled water and surfactant then an IPA rinse might be acceptable?? I can't get the guck off with IPA alone.? Can anyone see why using volatile organic solvents on the purely metal parts would be a problem? The airline, load and main body are free of contaminants.? the lock and slider works fine.

I'm laser-cutting a replacement EVA insert for the box.? I hope it won't turn to goo and powder in my remaining lifetime.

Last question, the spec says the gap between the shoulder of the N mail pin and the face of the female socket should be 0.001" to 0.007" but the 905A manual suggests pressing the plunger until the pin stops moving, then locking it.? That doesn't feel at all sensible to me.? I'd prefer to push it gently in, then back it off by a tiny amount in case there's any differential thermal expansion/contraction that might cause excess pressure on the socket/pin.

Neil, there are several versions of the Microwave Connector Care document but this HP 1986 version has the most N connector data on pages 45-52, see in particular figure 19 on page 48 for the effect of a gap.?



With my 905A I prefer to follow the manual instructions to butt out all gap but then engage the bidirectional lock knurled sleeve only as firmly as needed to keep the sliding load operating friction from disturbing the butted central line connection.?

Play with the lock tightness and line end knob when not connected to any connector so you get a feel for the choice you have in lock firmness.? In my use the connection is brief, but if you should go off and leave the sliding load connected and then temperature cycle the lab, the habit of engaging the lock only as firmly as necessary for measurement will allow the lock clutch to slip if and when needed so the sliding load central line gives rather than pushing over the center conductor of the VNA instrument.

Wally

Thanks Wally, that protocol sounds good.? I see the mismatch curve is at much greater separations than I was thinking, with the smallest entry on the chart being 5 mils, which is close to the max specfied anyway.? I was worrying about if I warmed up the outer but not the inner, then fixed the lock, then let it cool, that might do some damage to an expensive socket, but I like your plan about only nipping the loick up lightly.
Thanks v much
Neil