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Question about "N" Type Connectors

J

JesseJamesNEC

Member
Dec 27, 2009
41
1
16
I had a HAM that I know tell me that the N Type connectors were a better connector to use, he went on to tell me that the reason was that they were better at conduting the RF. I find that a little hard to believe personally so I was wondering if anyone knows if they truly ARE better and if so, why don't most CBs have them?? :confused:
 

At 27 mhz I would not worry the issue.
The pl258 is lossy at higher frequencies. But not enought to worry about at 27 megs.
If you were running a long run say at 144 to 440 mhz then yes, use the N-type.
Pl-259's are fine for cb.
 
JesseJamesNEC said:
I had a HAM that I know tell me that the N Type connectors were a better connector to use, he went on to tell me that the reason was that they were better at conduting the RF. I find that a little hard to believe personally so I was wondering if anyone knows if they truly ARE better and if so, why don't most CBs have them?? :confused:
Click to expand...

Jesse, I don't know about the comparative nature of conductivity between the PL259 and the N Type connectors, but I believe the big difference is the physical size differences these two connectors present to the characteristics of the coax. If the connector changes the dimensional relationship of any coax component then you will likely get an impedance bump.

If you compare the end views of these two connectors you will see that the N Type is much closer in the cross sectional dimensions of typical 1/4" coax---relative to the shield, insulator, and center conductor. In this manner impedance bumps (losses), most noted when using the PL 259 connector, are greatly eliminated when using a correctly installed N Type connector.

This issue is about the symmetry of all elements making up the coax, and the connector design and installation keeping the terminations of the shield and center conductor as close together as possible---in order to reduce radiation as much as possible at the coax connection.

Also look at the end views of some cheap coax compared to some quality coax you may have laying around. You may find it not uncommon to see the center conductor of the cheap stuff positioned off center in the insulation and it varies along the run. This variation in construction can also cause bumps and other variations in the impedance and velocity factor.

Conclusion: if we have to make a coax connection, we want the components of that connection to be as physically similar to the dimensions of the coax as possible, and in all respects---so the connection point appears as transparent as possible to RF.

If each connector is done correctly, does this make a noticeable difference in the CB area, probably not enough to really tell---except when using high wattage transmissions or operating higher in frequency.
 
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Here's my cut and paste from my reply on the other forum where you asked this.

N connectors do not conduct RF better but they are a much better connector. PL-259's are good up to the VHF region but they are NOT a constant impedance connector. This means that the impedance of them does not stay constant with changes in frequency and by changes I mean over several bands. They can introduce an impedance bump in an otherwise perfect 50 ohm system. The N connectors are indeed a constant impedance connector and well suited for RF up into the gigahertz range where PL-259 fall on their face. Type N connectors are also weather resistant, not weather proof, but resistant and have a rubber O-ring seal inside. They are a bit of a pain to assemble but well worth it if running UHF frequencies. They now have some type N connectors that install basically just like a PL-259 making it much easier but I have not used any of them yet. I still install the old harder to deal with type. BTW all professional or commercial communications equipment except maybe some mobile radios on VHF and above frequencies do have type N connectors on them.
 
If I am not mistaken n connectors have a rubber o ring or washer making them weather/moisture resistant, I might be wrong about this but they are a constant impedance connector and are physically stronger ( I think) than UHF connectors plus they are rated for 900 watts or 1kw cw I think... I like n connectors, just a little harder to put on, plus the center connector is a taper fit, much more secure.
 
A few things ..

SO239 is designed for working up to 300 Mhz Only
Even if one is looking for low loss on 144 mhz then SO239 should not be used..

Also N connectors follow the military standard MIL-C-39012 and is designed for use up to 20Ghz..
But N connectors also are designed to keep their quality with many connect and re connections.Type N uses an internal gasket to seal out the environment(giving it better weatherbility).
Also N works better for Very High power levels.

Will N connectors work better on 27 Mhz..
Yes..However they can cost quite a bit more and are harder to assemble .

For 11 meters/27Mhz i would Not worry about using N connectors unless you plan on using extreme power (and then only maybe)

If however you do go to use N connectors..
Then so too you likely would be using far better coax
(like Heliax or at Very Least LMR600 or better)
I happen to use Heliax LDF5-50A with N connectors ( for HF )
But my N connectors are $175 a piece ( a bit excessive indeed)
 
Marconi said:
Jesse, I don't know about the comparative nature of conductivity between the PL259 and the N Type connectors, but I believe the big difference is the physical size differences these two connectors present to the characteristics of the coax. If the connector changes the dimensional relationship of any coax component then you will likely get an impedance bump.

If you compare the end views of these two connectors you will see that the N Type is much closer in the cross sectional dimensions of typical 1/4" coax---relative to the shield, insulator, and center conductor. In this manner impedance bumps (losses), most noted when using the PL 259 connector, are greatly eliminated when using a correctly installed N Type connector.

This issue is about the symmetry of all elements making up the coax, and the connector design and installation keeping the terminations of the shield and center conductor as close together as possible---in order to reduce radiation as much as possible at the coax connection.

Also look at the end views of some cheap coax compared to some quality coax you may have laying around. You may find it not uncommon to see the center conductor of the cheap stuff positioned off center in the insulation and it varies along the run. This variation in construction can also cause bumps and other variations in the impedance and velocity factor.

Conclusion: if we have to make a coax connection, we want the components of that connection to be as physically similar to the dimensions of the coax as possible, and in all respects---so the connection point appears as transparent as possible to RF.

If each connector is done correctly, does this make a noticeable difference in the CB area, probably not enough to really tell---except when using high wattage transmissions or operating higher in frequency.
Click to expand...

Nice explanation.
 
Ok, so real world scenario:

I build a J-pole for 440 MHZ use, feed it with 50 foot run of 9913, using N connectors. Now if I were to change those to PL-259 connectos, everything else staying the same, would I really notice any difference? Would it be measurable?

I tend to doubt it. I've always been told PL-259s get lossy at some point, and I also understand that they don't maintain a constant impedance like the type N does, but nobody I've talked to has ever really been able to quantify it for me when we are talking ham bands like 2m and 70 cm.
 
Thanks for the great explanation Marconi! I appreciate that! Thanks to everyone else too I really was curious and now I have to say that by the sound of it for 11 meters anyway, stick with the PL-259's :)
 
Highlander_821,
I hate 'N' connectors. I have lots of trouble with them, or with putting them on really. Ruined two of them and quit trying, since most of what I do can be done with PL-259s.
I think I would tend to agree with you about the differences between the '259's and 'N' connectors. there definitely are differences in performance, but not easily quantifiable, sort of, at least for me.
What the devil is the name of those 'other' connectors that look a lot like a PL-259? Can't think of it right now. They are very nice too! Also not as easy to put on as a '259. Oh well, ain't always easy being this lazy...
- 'Doc
 
Highlander_821 said:
Ok, so real world scenario:

I build a J-pole for 440 MHZ use, feed it with 50 foot run of 9913, using N connectors. Now if I were to change those to PL-259 connectos, everything else staying the same, would I really notice any difference? Would it be measurable?
Click to expand...

Certainly measurable...real world difference...no.
 
What I never understood is why we don't use BNC???

Especially for VHF and UHF?
 
That analysis is interesting, and I certainly don't understand what all the figures mean.

But it seems like, for my scenario with the 440 band, I might be looking at a loss of about 1 DB by going with PL-259 over type N. For my purposes, that doesn't seem like anything to lose sleep over. If 3 DB amounts to 1/2 of an S-unit, then what does 1 DB equate to--1/8 of an S-unit? Oh boy.
 
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