Anyone know what this RF connector is?

(See the picture below; I put the unknown jack next to a TNC tee.) I have a threaded male connector that is similar to TNC (the threads will connect to a TNC jack), but the center pin is recessed, with its end at the base of the threaded portion. Can anyone tell me what it is called? I've spent a couple hours reading over connector information and looking at various companies' offerings of adapters, but so far I haven't been able to identify it. (I care about it because it's on an adapter connecting to APC-7 on the other side, and I'd rather not spend the money on other APC-7 adapters for just fooling around with an old network analyzer in my basement if I can find a cheaper adapter from this thing to a common plug.)
Thanks!
- Clint

In case it helps anyone, supposedly it came from a "MA-COM test kit."

looks like a tnc. popular with commercial radio guys

I believe they are SMA connectors. Google "SMA connector" and check "Images".

To clarify - the tee is TNC, and the unknown jack is on the right. It is thread-compatible with TNC (and thus too big to be SMA), but the center conductor does not reach the receiver in the TNC plug.

The centre conductor looks very thin, is it a 75 ohm TNC? Though I have never seen one. Could it be a properly made F type, as used on CCTV installation, but without the centre conductor, they use the cables inner conductor.
Frank

RP-TNC for WiFi. http://www.rfcoaxcable.com/support/r...roduction.html
A great invention by FCC to make it impossible to connect too directive antennas (same idea as with RP-SMA).
Can be found at Cisco Aironet.

chuckey - I'm pretty sure it isn't 75ohm, because the other side of the adapter is APC-7, which has a 50-ohm impedance.

E Kafeman - It's the same polarity as normal TNC, but the pin is recessed; thus, it isn't RP-TNC.

Thanks for the suggestions though!


My best guess at this point is that it's some sort of proprietary connector, but I welcome any other ideas that people have...

I see the mistake now, it have similar geometry as of a RP TNCA (A=air isolation) but center pin should be female.
Due to its TNC similarities some guesses, TNC exist in a lot of subversions, TNCA, AFTNC, 75 Ohm, several unnamed MIL spec, both EU and US, but as it also seems to be an APC7 adapter, Maury have made some unusual APC7 adapters which consist of several sub-adapters which then are mounted on the APC7 part. You can send the question to Maury, they have a good customer service.
Maury does also make VNA calibration kits, so next guess is that it not is a connector, instead is it a part of a calibration kit, an open that lost its cover. Reason why is that it from photo not are any visible traces from contact fingers that normally is needed to get a fresh contact-area each time two connectors are bolted together. But, looking again at the photo, treads seems worn, then must it be something else then a lost cover cap for a calibration kit.
That was my ideas, and all seemed wrong...
If you know something about its history, do you have corresponding female contact or where it have been used can such be clues.

E Kafeman - Unfortunately, I only know that it came from a "MA-COM test kit," if that means anything helpful to you. Thanks!

scope this out:
http://www.maurymw.com/pdf/datasheets/5A-031.pdf

there are variations to the "TNC" design, probably to extend the frequency to 18 ghz

Thanks biff44 and E Kafeman; I'm guessing it's one of the less common "TNC" connectors, but I haven't figured out which one yet.