You're way over-thinking this whole coax topic... I can't imagine a coupler making a bit of difference, and would be shocked to hear that there was any sort of standard (de facto or otherwise) about the insulation color on a coupler. The different frequency ratings on all of the ones you listed are probably based on the age of the product description than anything. Meaning they'd probably all test to 3GHz if someone went back to do it...

 



Quote:
Originally Posted by jautor  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23589212


You're way over-thinking this whole coax topic... I can't imagine a coupler making a bit of difference, and would be shocked to hear that there was any sort of standard (de facto or otherwise) about the insulation color on a coupler. The different frequency ratings on all of the ones you listed are probably based on the age of the product description than anything. Meaning they'd probably all test to 3GHz if someone went back to do it...

Heh, you're probably right. I'm probably at the point where I'm doing a little too much research. Nevertheless, the type of coupler you use can affect the signal quality.

Case and point: A few years back, we got cable Internet service and immediately started having issues. We were told by our ISP to change all intermediary devices (i.e., splitters, couplers, etc.) on the line to those rated for digital cable, and when we did, everything worked flawlessly. Before that, the cable line only carried CATV and there were no issues.



-amanisdude

__________________

 

Splitters can, and do, affect the signal and if not designed to support the higher frequencies, WILL cause problems. That is what caused your digital cable issue, not the couplers, which are simply pieces of metal...

 



Quote:
Originally Posted by jautor  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23589477

Splitters can, and do, affect the signal and if not designed to support the higher frequencies, WILL cause problems. That is what caused your digital cable issue, not the couplers, which are simply pieces of metal...

They may be just pieces of metal, but different metals have different conductive properties. I would imagine that this applies to F-81 couplers, too.


In computer networking, which is where I have most of my cabling experience, the use of a single coupler which is not rated for a particular cable could downstep the performance of the entire network (e.g., using an 8C8P RJ45 CAT5-rated coupler to join two CAT6 cables can downstep a connection to 100BaseTX, even if all other equipment is gigabit Ethernet-capable).


Granted, there is a difference between twisted-pair and coaxial cabling, so I suppose the same may not apply to linking two RG-6 cables. But if that's the case, what's the purpose of rating couplers, anyway?


Even DirecTV has a "ratings standard" when it comes to couplers. Why the persistent recommendations for using special "high frequency" F-81s for satellite and other microwave-range transmissions if it doesn't actually make a difference?



-amanisdude

__________________

 



Quote:
Originally Posted by amanisdude  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23589932


In computer networking, which is where I have most of my cabling experience, the use of a single coupler which is not rated for a particular cable could downstep the performance of the entire network (e.g., using an 8C8P RJ45 CAT5-rated coupler to join two CAT6 cables can downstep a connection to 100BaseTX, even if all other equipment is gigabit Ethernet-capable).

It *could* affect the performance of that link, but not "the entire network"... And again, we're really getting into "in theory" but not generally in practice, for residential use and cable lengths.

Quote:
But if that's the case, what's the purpose of rating couplers, anyway?

While again, I suppose in theory it could make a difference, but I'll go with the more plausible reason given the industry: you can get suckers to pay more for one if you say it's "3GHz rated"...

 

I've never heard of a speed rating on couplers as well.


fyi, I just looked at the couplers I order and they actually say they are 3Ghz rated, but they have white ends, weird.

 



Quote:
Originally Posted by amanisdude  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23589120


Is there actually any kind of standard when it comes to colorizing F coupler barrels...?

No.


FWIW the Ghz rating for f-type barrel connectors is pure marketing fluff. Any properly constructed barrel connector is adequate for your purpose.

 



Quote:
Originally Posted by Colm  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23590264


FWIW the Ghz rating for f-type barrel connectors is pure marketing fluff. Any properly constructed barrel connector is adequate for your purpose.

Thanks.

I suppose as long as the conductor inside doesn't zig-zag all over the place, any F-81 should do.


But if all good couplers work and high-speed barrels are the most desirable, why market ratings lower than 3 GHz at all? Somebody'd be bound to come out of the woodwork and take existing "low rated" conductors, paint them blue, and market them as cheap, 3 GHz-rated products without having committed any kind of false advertising or strongly questionable business practices.


There must be some sort of rating test for these things, especially since companies like DirecTV sometimes actively bring and replace existing couplers with "rated" ones, which is an added expense, right?



-amanisdude

__________________

EDIT: Come to think of it, I have found these things for cheap. Go figure. Anyway, I'm spending a lot to rewire the whole house, might as well go the minimal distance and get these 3 GHz ones.

__________________

 



Quote:
Originally Posted by amanisdude  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23590614


I suppose as long as the conductor inside doesn't zig-zag all over the place, any F-81 should do.

That is actually part of it. How well the connector performs depends in part on how well the geometry is controlled. F-connectors don't control the geometry of the center conductor particularly well because they rely on the center conductor of the coax to make the connection. Some connectors work better than others in this aspect, and some cables.

Quote:
There must be some sort of rating test for these things...

There are tests, just no simple industry standard rating that you can rely on. You have to read the datasheet for the part and look at return loss and insertion loss at the frequency of interest. Some parts do perform better a 3GHz than others. But that is irrelevant if you never have a signal over 2GHz.


If you have to have a "3GHz part", IIWY I would go with the Holland G series.


Why do satellite and cable companies go with parts like the Holland G series? They are betting on better reliability over time. That means fewer call backs and lower costs in the long run. They want a one size fits all approach so that their installers don't have to think. Lots of reasons that don't have anything to do with the part's performance at 3GHz. And maybe they even have plans for expanding bandwidth. Who knows?

 

Actually the F-81 you use can make a difference, more so than the F-6 (or F-59) connectors you use. This is primarily because of the way the center conductor is gripped. From: http://www.scte.alaska.com/Training/11FWD%20Sweep%20&%20Balance_new.pdf





EDIT: The same can apply to splitters.

 



Quote:
Originally Posted by Colm  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23590862


If you have to have a "3GHz part", IIWY I would go with the Holland G series.

Thanks for the recommendation.

But looking into it, even the same Holland G series F-81s seem to be rated differently on different sites:


- http://www.techtoolsupply.com/ProductDetails.asp?ProductCode=G-F81F

- https://www.perfect-10.tv/webstore/ProductDetail.aspx?ID=3331


The tech doc for the G-F81F does seem to make unnamed distinction between two different kinds of Holland G-F81Fs:


- http://www.3starinc.com/manuals/Holland-F-Splices.pdf


...although they both seem to be rated at 3 GHz in the official document.

_________________

Quote:
Originally Posted by olyteddy  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23591200


Actually the F-81 you use can make a difference, more so than the F-6 (or F-59) connectors you use. This is primarily because of the way the center conductor is gripped. From: http://www.scte.alaska.com/Training/11FWD%20Sweep%20&%20Balance_new.pdf

Wow, what a doc! It'll take me weeks to parse this using Wikipedia!

At any rate, I was sure the design of the barrel would have some effect, however minuscule. Now just to read up on this and understand more than is probably necessary. ^_^

__________________


-amanisdude
__________________

 

I agree some barrels may be better than others at gripping, but half my house has old white faceplate barrels and the other half with new blue.I see no difference in picture quality.

 



Quote:
Originally Posted by Skytrooper  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23591669


I agree some barrels may be better than others at gripping, but half my house has old white faceplate barrels and the other half with new blue.I see no difference in picture quality.

And you probably won't. The difference can be up to several dB and appear as a suck-out (loss of one or more frequencies) or as a slope (difference in level between low channel and high channels). Assuming adequate signal to begin with most tuners can tolerate this. However, I bring this up because I was a Cable TV Sweep tech and in that world .25dB (or less) can make or break a successful sweep trace.

 



Quote:
Originally Posted by amanisdude  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23591221


...the same Holland G series F-81s seem to be rated differently on different sites...

Ignore what the sites say. Look at the manufacturer's documentation.

Quote:
The tech doc for the G-F81F does seem to make unnamed distinction between two different kinds of Holland G-F81Fs...

Unless I am missing something, the electrical performance is the same for all of them. The only difference is mechanical.

 

.25 DB is like nothing. What is a sweep trace and how can .25 DB affect anything?

 

A sweep tech is the person who ensures that a cable system is operating optimally. This basically means the frequency response is within a couple dB of flat at any point in the plant. A sweep trace shows how close to that you actually are.


Examples:



PS: Those cheap F-81s can produce a sweep similar to the center one above.

 



Quote:
Originally Posted by Colm  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23590862


You have to read the datasheet for the part and look at return loss and insertion loss at the frequency of interest.

Quick dumb question. Is a higher or lower return loss or insertion loss more or less desirable? The standard Holland F-81s seem to have a higher insertion loss than their sister couplers in the G series, but also have a lower return loss. ( See here. )


I am inclined to think you want less "loss" overall, but I'm uncertain which is more important to watch out for with couplers: return loss or insertion loss.


I'd still probably go for the G-F81s anyway because they're "high performance", but I'm trying to learn something here.

-amanisdude
__________________

 

The color of the barrel doesn't really mean too much, though generally white means low frequency and blue means high frequency (tested to 3ghz). Don't pay much attention to"directv ratings standard" . All these companies have approved parts lists so they can more easily pass or fail in their joke of a quality control. However any good tech knows that many parts that aren't approved will work just as well or better.


As far as the color, blue is the standard for high frequency (rarely I've seen green as well). With Directv, red denotes power-passing, and I believe orange denotes SWM. With Dish for example, a host port on a node or tap is colored purple and the client port is orange. So basically don't worry too much about the color beyond white and blue. I use a hundred of these a week: http://skywalker.com/Products/ASKA-AF81-CB-F-81-Splice--30GHz--UL--qty-100__ASK1001.aspx

 



Quote:
Originally Posted by amanisdude  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23593568

Quote:
Originally Posted by Colm  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23590862


You have to read the datasheet for the part and look at return loss and insertion loss at the frequency of interest.

Quick dumb question. Is a higher or lower return loss or insertion loss more or less desirable? The standard Holland F-81s seem to have a higher insertion loss than their sister couplers in the G series, but also have a lower return loss. ( See here. )


I am inclined to think you want less "loss" overall, but I'm uncertain which is more important to watch out for with couplers: return loss or insertion loss.


I'd still probably go for the G-F81s anyway because they're "high performance", but I'm trying to learn something here.

-amanisdude
__________________

BIG return loss, small insertion. Also collet style grip instead of spring clip.

 



Quote:
Originally Posted by olyteddy  /t/1484297/type-f-coupler-insulator-barrel-color-codes#post_23593941

BIG return loss, small insertion. Also collet style grip instead of spring clip.

Thanks.

-amanisdude

__________________