F connectors

oconnorw

Could someone tell me what is the difference between using F Connectors over the ordinary connectors

Greenman

What do you mean "the ordinary connectors" ?

oconnorw

apologies coax connectors versus f connectors

Greenman

Maybe I'm missing something but anyway F connectors screw into F connector sockets and I think you mean the connectors called RF connectors well female fits male.
As I said maybe I'm missing something

watty

Common Coax connectors:

RCA Audio / Phono
N-Type
SMA
Reverse sex SMA (wiFi)
F-Connectors (USA TV coax plug)
Belling Lee (common Europe/UK/Ireland TV aerial coax socket)
PL259 ("UHF" coax)
BNC (50 and 75 versions)
Vampire Taps (original thick coax ethernet to 15 pin network card)


Which connector do you mean?

F-connectors come in two kinds, Crimp or screw on

They come in two sizes, bigger hole is for CT100 satellite grade cable and smaller hole version for cable TV type cable RG59 typically.

N-Type can take skinny RG58 or very fat RG213/RG6.

Usually the only choice is solder / screw or crimp. The actual *kind* of coax connector is constrained by the equipment used, i.e.
LNB and Satellite box = F-Connector
Professional LNB, LNA = N-Connector
Communications gear = BNC, PL259, SMA or N-Connector.

Cheap indoor aerial amps may use regular "belling lee" TV set plugs. Some masthead amps use bare coax cable and screw terminals. Professional models may use F-Connectors, BNC, PL259 or N-Connectors.

75 Ohm cables / systems tend to use F-Connectors, Belling Lee or 75 Ohm BNC.

50 Ohm cables / systems NEVER use Belling Lee (TV set connectors) or F-Connectors.

Almost ALL TV, LNB, Analog/Digital Satellite Receivers, mast amps and TV distribution amps are 75 Ohm and must use 75 Ohm cable and the appropriate connections.

Computer "thin-net"/"cheapernet" RG58 coax and / OR BNC plugs can be used for CB rigs, HF radios and scope / test equipment patch cables (it is 50 Ohms). It is no use for TV, FM Radio or Satellite coax connections which are 75 Ohm.

You can't measure the 50 or 75 with a mulitmeter on resistance, between inner /outer it is open circuit (infinite Ohms) and close to zero ohms between outers at ends or inners at ends.

The 75 or 50 refers to Transmission Line impedance "seen" only by radio frequencies. It does not matter to microphones or audio cable usage, any kind of coax cable will work for audio.

Spocker

At the end of the day they just do the same thing - they connect coax cable to a coax socket. The only real advantage of the F connector is that it gives a better, tighter connection - less likely to fall out/become loose if you stand on the cable.

If making your own cables used the crimp type connectors - they say on longer than the push on ones

watty

Crimp connections can be MUCH WORSE!

They ARE better if:

1) The cable and crimp connector are match
2) You have a professional crimp tool
3) You have been trained/know how to prepare and assemble the plug/cable

Crimp or screw in kind of F-Connector will "pull out". neither is designed to take any punishment. N-Connectors are the most robust kind, with the rubber sealing gland and nut / washer etc, but are never used on Domestic LNB and Receiver.

A few tie wraps (not too tight, as pinching the cable or flatenning it affects the signal) should be used to ensure no strain is on the F-Connector.

Exposed connections should have self-amalgamating tape or watertight rubber boots.

Tony

a good screw on connection is always better than a bad crimp on.

I think what you may be referring to is the standard "belling lee" connector, these are fine at lower vhf/uhf frequencies but F connectors have lower loss so are better at the higher satellite freqs. I also use them at vhf/uhf as they are faster to terminate and tend to be more robust.

Tony

Marty

Does it make any difference if the outer metal section of the screw on F-Connector (i.e the threads), does not touch the sheilding on the cable (the foil/outer mesh)?

watty

The foil should be removed and enough braid equal to length of barrel folded back over the outer plastic. Otherwise it will be too loose.

The screen braid *MUST* connect.

See my page at http://homepage.eircom.net/~watty/satellite/sathowto-p8.htm




The cable ready to have connector "screwed" on.

watty

This
http://homepage.eircom.net/~watty/satellite/sathowto-p9.htm

shows how to make up a "Belling lee" without solder. Kinking the inner wire helps make a good connection.

Tony

Hate to disagree but I always have the braid on the outside of the clamp.

Tony

Originally posted by LurkingIcon
This
http://homepage.eircom.net/~watty/satellite/sathowto-p9.htm

shows how to make up a "Belling lee" without solder. Kinking the inner wire helps make a good connection.

watty

My photo not good for that.

Braid definately looks a bit "motheaten"

Hmm. usually I have enough braid to alternately go in /out the legs of the clamp. Not one of the clearer illustrations.

Tony

heres some better photos http://www.megalithia.com/elect/bellinglee/

Greenman

This is what we use here in Belgium. I think they are great!!!!

Tony

Originally posted by greenman
This is what we use here in Belgium. I think they are great!!!!

looks good JD but the exposed centre conductor might act like a small ant dont you think? any TVI (interference) problems with these?

Tony

watty

Originally posted by Tony
heres some better photos http://www.megalithia.com/elect/bellinglee/

Yes that is good.

But most people wont be able to solder the middle pin. Not without melting the insulation.

Now for the next stage, there's a right way and two wrong ways to do it. If you are going to solder the inner conductor. you have selected the right way. If you absolutely insist you can't solder the inner conductor, then at least bend it about 10 degrees 0.5 cm from the end so it makes contact with the pin when the plug is freshly made. That will last you about 6 months to two years of acceptable contact in practice. If you don't bend it all bets are off - you are about to make a scratchy, intermittent connection whatever you do. The choice is yours.

You naturally take pride in your work and so you're going to solder this. In that case don't bend the inner at all.

Above extract says the dilemma well
The other problem is plugs with a clamp unsuitable for the thickness of TV 75 Ohm coax (which is basically encountered in 4 sizes, though only RG59 and CT100 thicknesses are common.)


I can't beleive a thread on F and Belleing Lee is going so long!

Tony

Originally posted by watty
Yes that is good.

But most people wont be able to solder the middle pin. Not without melting the insulation.



I can't beleive a thread on F and Belleing Lee is going so long!

I agree soldering is overkill, a bend in the centre always does the trick. I guess we are real termination anoraks:D

watty

Cue picture of Tony and Watty with large Solder guns, portable mini-gas irons and holster mounted Temperature controller "Weller's" also slim yellow "Antex" in shin holster.


"We'll be back"



Images from Terminator X (c) C.O.N.F.U.S.E productions (Ireland) Ltd.

ShaneOC

Ohhh - I've updated the C.O.N.F.U.S.E. thread .

Greenman

looks good JD but the exposed centre conductor might act like a small ant dont you think? any TVI (interference) problems with these?
No Tony nothing!!!:)

Heres more from my collection of RF connectors!!!

Greenman

And one for the road!!!:)

tv3tg4

I am looking for a an F-connector terminal (75 ohms)- where in Cork or Limerick would they be available?

winston_1

Tony wrote: »

Originally posted by watty
Yes that is good.

But most people wont be able to solder the middle pin. Not without melting the insulation.



I can't beleive a thread on F and Belleing Lee is going so long!

I agree soldering is overkill,  a bend in the centre always does the trick. I guess we are real termination anoraks:D

No, soldering is essential. A bent centre will make poor contact eventually, although RF will still get through due to coupling. But if you have DC for a mast head amp you WILL eventually have problems.

The Cush

winston_1 wrote: »

No, soldering is essential. A bent centre will make poor contact eventually, although RF will still get through due to coupling. But if you have DC for a mast head amp you WILL eventually have problems.

Reply to a 14 year old post, must be a record.

Johnboy1951

The Cush wrote: »

Reply to a 14 year old post, must be a record.

I am sure Watty would be impressed

31-03-2004 - Watty

I can't beleive a thread on F and Belleing Lee is going so long!

icdg

Er, indeed. We don’t drag up old threads