I'm looking to order Caplugs caps (or similar) for the RF connectors on
my instruments and test cables. I'm starting this thread for two
reasons:
1. to get advice from others about cap styles and sizing
2. to summarize my findings and make it easier for others buying caps
for the same application.
The caplugs style of having a small ridge on the edge of the cap seems
convenient as it should be easy to remove the connector. I have existing
round vinyl style caps that can be a bit cumbersome to remove.
My plan is to use conductive caps for instrument connectors and static
dissipative caps for cable connectors. The conductive caps are probably
slight overkill in most contexts, but, while I'll always leave them on
the equipment, I think they'd be particularly useful for things like
transport where the equipment will likely be exposed to blankets and
other possibly non static dissipative materials. So, the moderate degree
of electrical shielding provided by these caps could make a difference.
The CEC series ()
seems to be the appropriate choice for conductive caps and the SEC
series () seems to
the correct choice for static-dissipative caps.
The table below enumerates RF connectors, their dimensions and the
associated caplugs caps and dimensions (you'll have to view this in a
monospace font for it to be correctly spaced). Dimensions are in D/L,
where D is diameter and L is length. For caps, the diameter and length
refer to the inside of the cap. For connectors, the diameter refers to
the outer thread diameter. Two numbers separated by a dash (e.g., D1-D2)
can be given for connector diameter. This is useful in the case of e.g.,
bayonet connectors which have additional protrusions in addition to the
cylindrical diameter. All dimensions are in inches. The number of digits
is not an indication of significant figures; I've simply chosen it to
line up numbers within columns. Finally, many of these dimensions are
based on measurements I've made myself and may be slightly off.
Please correct any mistakes you find. In particular, I haven't tested
any of these caps, I've simply guessed which size I think would work
best. Also, please feel free to respond with dimensions/caps for any
other connectors. I've simply presented the ones most applicable to me.
| RF connector | dimensions | CEC | dimensions | SEC | dimensions |
| <l> | <c> | <c> | <c> | <c> | <c> |
|--------------+-------------------+--------+-------------+--------+-------------|
| SMA female | XXXXX-0.250/0.230 | CEC-04 | 0.244/0.490 | SEC-04 | 0.245/0.500 |
| SMA male | 0.312-0.350/0.335 | CEC-06 | 0.368/0.510 | SEC-06 | 0.360/0.500 |
| BNC female | 0.386-0.436/0.418 | CEC-07 | 0.430/0.630 | SEC-08 | 0.480/0.500 |
| BNC male | XXXXX-0.573/0.550 | CEC-10 | 0.607/0.500 | SEC-10 | 0.600/0.500 |
| N female | XXXXX-0.620/0.430 | CEC-10 | | SEC-10 | |
FYI caplugs offers free samples so in absence of information from people
who have tested various caps, I may get some samples, test them out and
report back here.
Other things to note: Mouser seems to be a better place to order these
than from Caplugs themselves. The per unit prices seem to be lower and
they allow smaller orders. Alternatively, I'm pretty sure the caps
listed on McMaster-Carr are caplugs
( and
) since the
sizes and styles appear to match up. Their prices also seem
reasonable. If anyone could confirm that these are indeed caplugs of the
CEC and SEC series that would be great. Otherwise, I'll probably clarify
this with them myself and post back here.
Matt
