How to properly use panel mount BNC connectors

I want to put a circuit (64MHz T/R switch + receiver LNA) in a generic aluminum box (something like this http://www.hammondmfg.com/pdf/1550D.pdf), but I'm hung up on what kind of connectors to use such that they don't screw up my 50Ω matching (especially on the antenna/coil port and the amplifier output port). I've been looking at several varieties of both panel mount and board mount BNC connectors, but am unsure how I should use them in my enclosure.

Here are a few types I have sitting around in the lab:
Digi-Key - A97552-ND (Manufacturer - 1-1337542-0) (seems nice, but takes up a huge amount of space on the PCB... are the PC pins actually a 50 ohm line?)

Digi-Key - A32341-ND (Manufacturer - 5227726-3) (I could just squish the PCB between the two contacts, but I still bet I would get standing waves. I also have these with a conducting body)

Digi-Key - ACX1049-ND (Manufacturer - 112290) (looks nice, but the PCB is going to be floating in the middle of the enclosure, only connecting to the enclosure at connectors. So again I have doubts as to whether having the connector shield connected directly to the enclosure, rather than directly to the PCB, is a good idea).

Thoughts/recommendations?

At 64 MHz, I do not see any matching problem with a panel-mounted BNC connector.
If your version has 2 or 4 screws, put soldering lugs on two of them, divide cable shield in two strands and solder.
If you have a screw-through BNC connector, use its grounding lug to solder cable shield to it.
More care is needed at frequencies > 200 MHz; BNC itself is not too good for >1..2 GHz.

jiripolivka said:

At 64 MHz, I do not see any matching problem with a panel-mounted BNC connector.

Click to expand...

That's what I would expect too, but I've been seeing problems when not careful. Like 1cm of signal trace causing degradation in my NF by 1dB. But I'm mainly concerned that if use a panel mount BNC which connects directly to the enclosure and not to the PCB ground, I'll get bizarre reflections or something.

If your version has 2 or 4 screws, put soldering lugs on two of them, divide cable shield in two strands and solder.
If you have a screw-through BNC connector, use its grounding lug to solder cable shield to it.

Click to expand...

I'd like to have the contacts of the connector solder directly to the PCB. No coax inside the enclosure, if possible (takes up lots of space).

I have not seen a suitable BNC connector to directly connect to a PCB.
Then I would suggest making a L-bracket of thin brass or tinned sheet, this can be soldered to PCB ground side and the center pin to board edge.

If your short PCB line degrades LNA noise figure by 1 dB at 64 MHz, to me it sounds like a bad mismatch rather than a loss. Please try to connect a series or parallel trimmer, 0-10 or 0-30 pF; you can tune your receiver to a better NF at 64 MHz.

purchase the silver plated BNC connectors, they will solder straight to the PCb without any problems

Dave