Rule of Thumb Uses For F-type connector

Shandy

A lot of our satellite stuff uses F connectors and the splitters often say 950MHz-2250MHz although I have encountered problems that went away when I used a different or better splitter.

The connector should have about the same impedance characteristic as the 75 ohm coax (at least in the case of our satellite receivers--should be a slightly different "F" type connector for 50 ohm--no personal knowledge of such) for which it is designed.

If the 950-2250MHz numbers actually indicate the bandwidth 3dB down points, the cable and connector should be centered at about 1600MHz. Your 1900MHz signal should be happy if you don't have to run it over a hundred feet or so.

Shooting from the hip here--I don't have personal knowledge of your application. Hope this is helpful.

Lonnie

Thanks for the feedback, Lonnie. We'll just go at it and see what happens. It should be alright but I just had an awkward feeling about using a consumer product in a normally commercial application.

Steve

Shandy:

Go to www.Firestick.com. They are a premier maker of antennas and have a good tech section on connectors. Another good source is the American Radio Relay League. If you can, get a copy of their handbook...buy it from them or search your local library. They get into the details of impedance matching, mechanical details of the fittings and how to make them up yourself, etc.

Enjoy!

Hank

So far as I know, "F" connectors are used only with 75 ohm cable WITH SOLID CENTER CONDUCTOR. Be sure the F connectors are suitable for the cable used. I would recommend using RG-6 cable rather than RG-59 as I believe it has lower loss up in the GHz frequencies. I tried to get some actual numbers for you, but my computer with that info is not cooperating this morning. I think it needs another cup of coffee. I would recommend using brand name quality F connectors at that frequency. Amphenol comes to mind.

BINGO!! I found my General Cable catalog! RG-6 has a typical loss of 6.59 dB per 100 feet @ 1 GHz. I also found RG-7 with a loss of 5.26 dB per 100 feet (but I don't know if you can get F connectors for it). RG-59 has losses ranging from 8.8 dB to 13 dB per 100 feet @ 1 GHz (depending on type) so I would stay away from that.

Another source which might be able to help you might be your local cable company. Those guys use 75 ohm cable till the cows come home... from 1 inch hard line down to the stuff your home is wired with. You might have to go through a couple of levels of hierarchy to get to someone technically competent. The gal who answers the phone thinks RG-6 is a foreign sports car made back in the '60s... but they might be more than willing to help you.

Now... back to the original question. I would search for Amphenol on line... probably amphenol.com or something similar. They should have frequency specs for their coax connectors available. Sorry but I don't have an Amphenol catalog handy.

Good luck

Bill

The F connector will work fine for this application. The type of coax used is what determines your signal loss. RG-6 quad shield, 18 gauge, will work fine for the frequency that you are working with. Thomas & Betts makes a great F connector called "snap n seal". The "old school" twist on or crimp style F connectors leave a lotta room for error. With the "snap n seal" connectors, you never have to second guess your connections.

Good Luck with this project!

Jeff

Hey Jeff!!

Thank you for supporting my argument for RG-6... and I didn't want him to go out to the local Radio Shack for his F connectors.

The product from T&B sounds like the F connector I was thinking of... They install so nicely... if you have the proper tool. and the F's are not cheap (I would guess)... but if you are going to approach the edge of the envelope (which you are doing), use first cabin transmission line and first cabin connectors. I agree fully with Jeff in the coax he recommends.

Jeff: I am curious if you have a brand for the cable you mentioned... I saw such a cable in the General Cable catalog I researched, but I didn't want to muddy the waters too much. I assume that Belden would have similar coax... and probably many other cable manufacturers.

Sincerely

Bill

Good Morning Bill,

Yes, most cable manufacturers produce coax in one form or another and there are several out there. As long as you spec RG6, 18 ga., quad shield, the cable will be what you are looking regardless if Belden or another company produces it. I think they have to meet a certain criteria that all cable manufacturers have to follow.

The reason that I choose "quad shield" is the fact that coax can emulate an antenna at times and can pick up RF signals from other source. The quad shield will prevent this.

Thanks!

Jeff

I cringe when I see coax spec'ed at "50% shielded". With that stuff (especially at 1.9 GHz) you could open a combination Hotdog stand and LAN. To cook the hotdogs, you simply split them half way through, and wrap them around your feedline.

Bill