# 50 Ohm Waterproof BNC Bulkhead Adapter With Dust Cap **URL:** \ **Category:** Interconnect\ **Tags:** coaxial-connectors, interconnect, connectors-interconnects\ **Created:** [April 19, 2023, 2:41am UTC](https://forum.digikey.com/t/50-ohm-waterproof-bnc-bulkhead-adapter-with-dust-cap/30313 "2023-04-19T02:41:31Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![KI6ESH](https://sea2.discourse-cdn.com/digikey/user_avatar/forum.digikey.com/ki6esh/32/34957_2.png) [@KI6ESH](https://forum.digikey.com/u/KI6ESH)\ **Post date:** [April 19, 2023, 2:41am UTC](https://forum.digikey.com/t/50-ohm-waterproof-bnc-bulkhead-adapter-with-dust-cap/30313/1 "2023-04-19T02:41:31Z")
For an amateur radio application (7 MHz - 28 MHz) I am seeking a 50 Ohm Waterproof BNC Bulkhead Adapter that I could place through a hole drilled in a Pelican case. I have located [this adapter](https://www.showmecables.com/by-category/adapters/adapters-coax/bnc/ip68%20waterproof-adapter-75-ohm) that looks perfect in every way _except_ that it is 75 Ohm instead of 50 Ohm. Is anyone aware of something similar at DigitKey for 50-Ohm applications? And if not here… anywhere else? I love that this one was BNC to BNC so I won’t have to solder or crimp any custom cables inside the box, just a BNC cable from the back of this to the radio. The documentation on that one states: > 50 ohm and 75 ohm BNC connectors will mate with each other. > At frequencies under 10 MHz the impedance mismatch will not have > any affect. If you are above 10 MHz the chances of signal distortion > become more significant. So it would likely cause problems with my uses on 20-meters (14 MHz) and 10-meters (28 MHz) but would work fine on 40-meters (7 MHz). ---
**Author:** ![rick\_1976](https://sea2.discourse-cdn.com/digikey/user_avatar/forum.digikey.com/rick_1976/32/1571_2.png) [@rick\_1976](https://forum.digikey.com/u/rick_1976)\ **Post date:** [April 19, 2023, 5:08pm UTC](https://forum.digikey.com/t/50-ohm-waterproof-bnc-bulkhead-adapter-with-dust-cap/30313/2 "2023-04-19T17:08:03Z")
Greetings, The nature of the BNC connector isn’t all that amenable to weatherization, making systems of the sort somewhat uncommon. [N or TNC](https://www.digikey.com/short/9ddt5mm4) styles are a bit more robust there and may offer a better slate of options. Whether protection in the mated or un-mated condition is of greater interest may also weigh on the matter. Regarding the impedance mismatch issue, information of the sort referenced is the kind one should take with a (large) grain of salt. Natural phenomena operate on a continuum; “work/no-work” demarcations applied to conveniently-round numbers in that way are a hallmark of loose approximations based on assumption and generalization. A 75 ohm feedthrough in a 50 ohm system _will_ have some adverse effect on performance, it’s simply a question of how much and whether or not it’s tolerable in context. Better to avoid it if possible. ---
**Author:** ![KI6ESH](https://sea2.discourse-cdn.com/digikey/user_avatar/forum.digikey.com/ki6esh/32/34957_2.png) [@KI6ESH](https://forum.digikey.com/u/KI6ESH)\ **Post date:** [April 19, 2023, 5:17pm UTC](https://forum.digikey.com/t/50-ohm-waterproof-bnc-bulkhead-adapter-with-dust-cap/30313/3 "2023-04-19T17:17:41Z")
Thank you so much for your reply, I really appreciate the details. I’ll keep looking for options and alternatives, but to answer your question: I was mostly interested in it being fairly watertight when un-mated. I liked the idea of the screw-on waterproof cover both to keep things dry and almost as importantly, to protect the connector during transport. Once I select a solution I’ll post my chosen item here just in case it helps anyone else in a similar situation in the future. ---
**Author:** ![rick\_1976](https://sea2.discourse-cdn.com/digikey/user_avatar/forum.digikey.com/rick_1976/32/1571_2.png) [@rick\_1976](https://forum.digikey.com/u/rick_1976)\ **Post date:** [April 19, 2023, 6:23pm UTC](https://forum.digikey.com/t/50-ohm-waterproof-bnc-bulkhead-adapter-with-dust-cap/30313/4 "2023-04-19T18:23:45Z")
> [@KI6ESH](#): > > I was mostly interested in it being fairly watertight when un-mated. [Protective caps](https://www.digikey.com/short/qm4q3vqt) for N & TNC are available, with GradConn’s offerings being rated to IP67 when used with their connectors. Depending on what you’re connecting to inside the box, there may even be a [cable assembly](https://www.digikey.com/short/hmnfjmmp) available, and it looks like customs can be had. Might be worth a look…