F connector sizes vs cables - what's going on? - UK Vintage Radio Repair and Restoration Discussion Forum

stevehertz · 7th Apr 2018, 12:08 pm

Can someone with plenty of experience of fitting F connectors to cable answer me this. I bought some F connectors specified as being for use with RG6 cable. RG6 cable is specified as being 0.332" or 8.4mm in diameter - and when you fold the braid back it's going be a tad more. The so-called RG6 F plugs that I received are 6.53mm internal diameter measured with an internal vernier gauge. Ok, so that's on the 'peaks' of the threads, there's a tad more diameter 'in there' accounting for thread depth, bite and squeeze. So, is that right, RG6 cable of 8.4mm+ diameter is expected to be crammed into a 6.53mm threaded hole? Doesn't seem right to me. What is the correct internal diameter of an RG6 plug? Do I have RG6 plugs from that supplier?

Actually, this isn't the end of the story! Because of the above situation, thinking that it was maybe my own fault or lack of knowledge I bought another lot of F plugs described as being for use with RG9 cable. Now RG9 cable is specified as being 0.42" or 10.67mm diameter. They too arrived measuring - you guessed it - 6.5mm internal diameter. My guess is there's a glut of these smaller size F connectors around and unscrupulous sellers are palming them off to unsuspecting buyers. But what size and/or type of cable are these 6.5mm internal diameter plugs supposed to fit? Fitted with brute force onto RG6 cable, or maybe slightly loose (?) on RG4 cable that is specified as being 5.7mm diameter (plus folded back braid) ?

......

Cobaltblue · 7th Apr 2018, 12:12 pm

I think the 6.5mm Connectors are the ones fitted to the generic Shotgun Satellite cable.

This is the cable so beloved by SKY etc.

Cheers

Mike T

stevehertz · 7th Apr 2018, 12:38 pm

Cheers Mike. Well, having just looked (I hadn't heard of it before) Shotgun cable is also know as WF65 Sky type (as you allude to), and that is specified as being 4.8mm diameter. But in that case, surely my 6.5mm I/D plugs would be too loose for that cable? I dunno...? Not that this matters much to me as I have't got Shotgun cable, but one of my queries was, what do these 6.5mm connectors fit? They don't seem to fit anything?!!

ms660 · 7th Apr 2018, 12:54 pm

RG59?

Lawrence.

stevehertz · 7th Apr 2018, 2:04 pm

Just looked it up Lawrence and RG59 is 0.242"/6.14mm diameter, so from someone who has never jointed an F connector (yet - still waiting for the right kit!) that would appear to be a good fit into a 6.5mm connector by the time the braid is also brought into the equation. Thanks.

But this F connector mullarky is an absolute minefield, what with the seemingly hundreds of different types of cables and diameters, non-easily matched connector denominations (pause for breath) plus.. the attitude - and probably limited knowledge - of many sellers, it's not easy to get a cable and plug that actually fit each other!

Jeremy M0RVB · 7th Apr 2018, 2:56 pm

CT100 sat cable is 6.55 or 6.65 od depending where you look.

stevehertz · 7th Apr 2018, 3:10 pm

6.8 here.

Herald1360 · 7th Apr 2018, 10:35 pm

So those connectors would be a good tight fit screwed onto CT100 cable......

philthespark · 8th Apr 2018, 4:30 am

I normally use the crimp on type, much more secure, but I will agree you have to be careful with any connector these days as a lot of people only sell the "popular" ones. I needed some for a job and having ran out called into Screwfix,I picked up a bag, drove a fair distance to the job only to find they wouldn't fit! They were the narrow ones as used on the shotgun cable when I asked at SF why they only sold these, I got the reply, "because they are what most people want".
Now ok, yes it was my fault because I shouldn't have let my stocks run out, yes it was my fault because I should have checked before buying them, but it would have been helpful if they had stated in the catalogue that they would only fit shotgun cable.

stevehertz · 8th Apr 2018, 7:34 am

Quote:

Originally Posted by Herald1360

So those connectors would be a good tight fit screwed onto CT100 cable......

Well, that's my question, are we supposed to be - somehow - fitting 6.8mm O/D cables (plus braid) into F connectors that have an I/D of 6.5mm? Sellers seem to think so. I'm not saying it can't be done, just trying to find someone who has done it! In engineering terms it's called an interference fit, but there's an interference fit and there's an interference fit. It gets to the point where it just doesn't fit!

vidjoman · 8th Apr 2018, 8:26 am

I have a selection that I keep so normally don't have a problem. I do find that connectors that fit a cable size often have a different sized hole into which the centre core insulator should just fit so the copper conductor can't touch the earth casing. It does seem a bit hap-hazard with each cable and plug manufacturer seemingly doing their own thing.

G8HQP Dave · 9th Apr 2018, 2:38 pm

It's a while since I fitted an F connector onto a cable, but could it be that sometimes you don't fold the braid back against the outer insulator but instead simply remove the outer insulator and screw the connector onto the braid in situ around the inner dielectric?

7th Apr 2018, 12:08 pm	#1
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,830	F connector sizes vs cables - what's going on? Can someone with plenty of experience of fitting F connectors to cable answer me this. I bought some F connectors specified as being for use with RG6 cable. RG6 cable is specified as being 0.332" or 8.4mm in diameter - and when you fold the braid back it's going be a tad more. The so-called RG6 F plugs that I received are 6.53mm internal diameter measured with an internal vernier gauge. Ok, so that's on the 'peaks' of the threads, there's a tad more diameter 'in there' accounting for thread depth, bite and squeeze. So, is that right, RG6 cable of 8.4mm+ diameter is expected to be crammed into a 6.53mm threaded hole? Doesn't seem right to me. What is the correct internal diameter of an RG6 plug? Do I have RG6 plugs from that supplier? Actually, this isn't the end of the story! Because of the above situation, thinking that it was maybe my own fault or lack of knowledge I bought another lot of F plugs described as being for use with RG9 cable. Now RG9 cable is specified as being 0.42" or 10.67mm diameter. They too arrived measuring - you guessed it - 6.5mm internal diameter. My guess is there's a glut of these smaller size F connectors around and unscrupulous sellers are palming them off to unsuspecting buyers. But what size and/or type of cable are these 6.5mm internal diameter plugs supposed to fit? Fitted with brute force onto RG6 cable, or maybe slightly loose (?) on RG4 cable that is specified as being 5.7mm diameter (plus folded back braid) ? ...... __________________ A digital radio is the latest thing, but a vintage wireless is forever..

7th Apr 2018, 12:12 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,864	Re: F connector sizes vs cables - what's going on? I think the 6.5mm Connectors are the ones fitted to the generic Shotgun Satellite cable. This is the cable so beloved by SKY etc. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

7th Apr 2018, 12:38 pm	#3
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,830	Re: F connector sizes vs cables - what's going on? Cheers Mike. Well, having just looked (I hadn't heard of it before) Shotgun cable is also know as WF65 Sky type (as you allude to), and that is specified as being 4.8mm diameter. But in that case, surely my 6.5mm I/D plugs would be too loose for that cable? I dunno...? Not that this matters much to me as I have't got Shotgun cable, but one of my queries was, what do these 6.5mm connectors fit? They don't seem to fit anything?!! __________________ A digital radio is the latest thing, but a vintage wireless is forever..

7th Apr 2018, 12:54 pm	#4
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: F connector sizes vs cables - what's going on? RG59? Lawrence.

7th Apr 2018, 2:04 pm	#5
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,830	Re: F connector sizes vs cables - what's going on? Just looked it up Lawrence and RG59 is 0.242"/6.14mm diameter, so from someone who has never jointed an F connector (yet - still waiting for the right kit!) that would appear to be a good fit into a 6.5mm connector by the time the braid is also brought into the equation. Thanks. But this F connector mullarky is an absolute minefield, what with the seemingly hundreds of different types of cables and diameters, non-easily matched connector denominations (pause for breath) plus.. the attitude - and probably limited knowledge - of many sellers, it's not easy to get a cable and plug that actually fit each other! __________________ A digital radio is the latest thing, but a vintage wireless is forever..

7th Apr 2018, 2:56 pm	#6
Jeremy M0RVB Hexode Join Date: Jul 2003 Location: Leeds, West Yorkshire, UK. Posts: 458	Re: F connector sizes vs cables - what's going on? CT100 sat cable is 6.55 or 6.65 od depending where you look.

7th Apr 2018, 3:10 pm	#7
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,830	Re: F connector sizes vs cables - what's going on? 6.8 here. Attached Thumbnails __________________ A digital radio is the latest thing, but a vintage wireless is forever..

7th Apr 2018, 10:35 pm	#8
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: F connector sizes vs cables - what's going on? So those connectors would be a good tight fit screwed onto CT100 cable...... __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

8th Apr 2018, 4:30 am	#9
philthespark Pentode Join Date: Oct 2017 Location: Newton-le-Willows, Merseyside, UK. Posts: 158	Re: F connector sizes vs cables - what's going on? I normally use the crimp on type, much more secure, but I will agree you have to be careful with any connector these days as a lot of people only sell the "popular" ones. I needed some for a job and having ran out called into Screwfix,I picked up a bag, drove a fair distance to the job only to find they wouldn't fit! They were the narrow ones as used on the shotgun cable when I asked at SF why they only sold these, I got the reply, "because they are what most people want". Now ok, yes it was my fault because I shouldn't have let my stocks run out, yes it was my fault because I should have checked before buying them, but it would have been helpful if they had stated in the catalogue that they would only fit shotgun cable.

8th Apr 2018, 8:26 am	#11
vidjoman Dekatron Join Date: Jun 2013 Location: East Sussex, UK. Posts: 3,326	Re: F connector sizes vs cables - what's going on? I have a selection that I keep so normally don't have a problem. I do find that connectors that fit a cable size often have a different sized hole into which the centre core insulator should just fit so the copper conductor can't touch the earth casing. It does seem a bit hap-hazard with each cable and plug manufacturer seemingly doing their own thing.

9th Apr 2018, 2:38 pm	#12
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: F connector sizes vs cables - what's going on? It's a while since I fitted an F connector onto a cable, but could it be that sometimes you don't fold the braid back against the outer insulator but instead simply remove the outer insulator and screw the connector onto the braid in situ around the inner dielectric?