• Dhruv Patel
    I figured that 1.85 mm and 2.4 mm connectors mate or are mechanically compatible. So, wondering why would someone buy a 1.85mm to 2.4mm adaptor (50 GHz bw) like the one mentioned in the data-sheet link below?

    I understand that if the test equipment is designed for 67 GHz operation (for 1.85 mm connector) then using such adaptor will limit the operation down to only 50 GHz. so not sure why would someone want to use such adaptor and limit the operation only up to 50 GHz (may be noise or insertion loss reason?) – would be wonderful to see some intuitive discussion on this.

    Is there any other specific reason for using such adaptor? For example, will my connector be damaged if I connect 1.85mm (M) into 2.4 mm (F) even though they are said to be mechanically compatible?

    Datasheet Link:
    SCT-2FVF-UB (234K)
  • madengr
    One reason would be reliability. The smaller the connector, the more likely it is damaged, so if you don’t need to go to 67 GHz, keep it at 50 GHz. Less expensive cal kit too.

    I have a 67 GHz PNA at work where I ordered 1.85 mm NMD to 3.5 mm cables, and a 50 GHz PNA with 2.4 mm NMD to 3.5 mm. Of course I have full 1.85 mm and 2.4 mm cables, but only hook those up when I need the extended frequency. Otherwise keep everything at 3.5 mm.

    Years ago some idiot at work force fit a 3.5 mm onto a 2.4 mm brand new spectrum analyzer. The threads are not even compatible (for that reason), but a monkey with a wrench can pull it off.
  • Rich
    It might give you a better unknown thru cal.
  • Bob Hawkinjs
    Sometimes engineers want a 1.85 to mate to a 1.85; & a 2.4 to mate to a 2.4; They don't want to worry if a 1.85 is 100% compatible with a 2.4, or 90%, or whatever. They play it safe.
  • David Lutton
    Anritsu MG369nB signal generators have 2.92 mm connectors for 10/20/30/40 GHz models and 1.85 mm for the 50/67 GHz models.
    We use a 1.85 mm to 2.92 mm adaptor on a 50 GHz Anritsu generator where it is used < 40 GHz most of the time. This also serves as a port protector.
  • UnknownEditor
    This might be milking mice, but the 2.4mm will have slightly less loss than the 1.85mm....
  • Kelly Garrison
    2.4mm has a 1mm "d" in a 2.4mm "D". 1.85mm has a 0.8mm "d" in a 1.85mm "D". Both are 50 ohm coax lines. But if you butt them to each other, you'll create a discontinuity at the transition step. The discontinuity can be tuned by offsetting one step from the other, but when mating a 1.85mm to a 2.4mm, this hasn't been done and the discontinuity remains. A properly designed adapter will tune out the step discontinuity.
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