I went to a computer store, not compusa, to look for a BNC to RJ45 adaptor. They did not have them, they had BNC to RJ11 however. The guy at the store said that the adaptor, which looks like this, wouldn’t do what I want it to do. What I want it to do is allow a network cable that terminates in a male BNC plug attach to a Linksys switch. Will that adaptor work or not, or do I need to spend more money and get something like this?
The guy was correct, that simple adapter will not do what you want.
I doubt you will find what you are looking for without shelling out some bucks. The one on shopper.cnet.com will do what you want - but is it really worth the cost? I would probably be cheaper to get a new NIC for the PC and new cat-5 cabling rather than run through a converter.
If you must stick with the coax cable, the best option is an older hub. Some of the older hubs had one BNC port and they will handle the conversion for you - and you could probably pick one up on eBay for less than a new converter. Here’s one currently going for $5. Plus you get some extra 10BaseT ports (yay.).
That is what I feared. What is the purpose of the connector then?
It turns out that we have an old 10Base-T hub laying around the office, but I’ll need another one, and I placed a bid on the one you linked to. That is a much cheaper option than replacing the coax that is already run to the end location. Thanks for the input.
If you don’t win the auction. I’ll see if I have a BNC+RJ45 combo hub hanging around gathering dust. If so you can have it for the shipping cost if you need one.
Yikes! - wouldn’t it be easier to spend less money and upgrade the NIC?
Me too, I have a Netgear EN104 hub with 4 RJ45 w/uplink and 1 BNC that I’ll send for shipping (FL).
Just to clarify a few things- the computers all have standard 10/100 NIC cards. My issue is that the wiring from where the internet connection comes in to where it terminates is coax and not CAT5. I have a little converter, like in the second link, to attach the cable modem to the end point. My concern was getting the connection from the end point to the computers.
I have one hub that hopefully works, and I did win the auction so I think that I should be set. Astro and yoyodyne, thanks for the offer, I may yet have to take you up on it, but hopefully not.
Are you absolutely sure that the computer you’re trying to hook-up only has a BNC connector? All of the systems with a BNC connector that I’ve seen (including some really crusty stuff like VAXStations and Nubus ethernet cards for classic macs) also have an AUI connector, and a switch that lets you toggle between the two. An AUI connector is gonna be a female DB15 port, so you may have mistaken it for video or serial of some sort. If it does have an AUI connector, you can get an AUI to 10baseT (RJ45) transciever relatively inexpensively. This is how I hook my VAX and Lisp Machine up. 
No computer here has a BNC connector, again they all have standard NICs. The only thing with BNC connectors is the cable running from our main office to our box offices. That is the way that we get the internet to the box office. We are not going to run CAT 5, as the boss is a bit tight-fisted. The device in beltbuckle’s is something that will work. The BNC goes in and RJ45 goes out, in essence it cuts out step I was planning on by rolling the BNC to RJ45 adapter with the Linksys switch into one package. Unless I am missing something, and since September has been technology nightmare month, it is possible.
I do a similar thing with LAN parties (I happen to have a large amount of coax 10BT cable, and two ancient dual-media hubs, which makes it the convenient thing to span large distances).
In your case however, I wouldn’t replace the switch with it. A switch is better than a hub, and is probably 100MB in any case, whereas the hub goes a max of 10MB (though IIRC, the coax only supports a max of 2MB/s, but anyhow).
I would hook the coax cable up to your new (old) hub, then slap a crossover cable from the hub to the switch. (Crossover cable perhaps not needed if either the hub or switch have an uplink port).
This setup would, given the equipment you have, maximize your total data throughput in all situations. (From the internet to your office machines, and inter-office machine for filesharing between workers).
Stupid question: You’re sure that the coax cable is carrying an Ethernet signal, right?
What is the point? The hub is going to cause a bottleneck either way.
Our internet in the office proper is a different connection than what is going to the box offices. Our office LAN is full on 10/100 and we have CAT 5 everwhere in the office.