N Connectors Only Above 500 MHz?

[SpectrumAnalyzer]

A while back I read somewhere in one of the communications Industry trade journals that N connectors are highly recommended over SO-239 connectors as the SO-239's are totally unreliable & vastly inefficient above 500 MHz, I did find this related article in The UHF type connectors under network analysis all this that is being said about the inefficiency of SO-239 connectors, would this really have a negative affect when just using receiving equipment like scanners & wideband receivers?

 

[jackj]

Short answer - YES

Why do you think that power determines loss? If a connector causes 3 dB of loss at 450 MHz then the loss will be 3 dB regardless of the power level.

That said, I got into commercial 2-way radio sales and service in the late 60's and stayed active until about 1980. I worked on mobile and base equipment that operated from around 30 MHz to 470 MHz. The only equipment that used N connectors was UHF duplexers, antennas and a few repeaters. Mobiles and simplex base stations seemed to work well with PL-259/SL-239 connectors. PL-259/SO-239 connectors will cause an impedance bump in the transmission line and that bump will reflect power back to the source. So if you are looking for perfection, use N connectors.

 

[cmdrwill]

The PL259 connector is a really old design back when UHF was 30 megahertz. And hence the UHF name.

 

[mmckenna]

Its getting pretty difficult (not impossible) to find UHF connectors on commercial gear. Yes, modern mobile VHF/UHF radios will have them, but I wouldn't be surprised if that changed in the next decade or so.
All my repeaters at work (10+) are all "N" connectors. On our 800MHz TX multicoupler, the output is 7-16 DIN. Most of the large base antennas we've purchased over the last few years for repeater use have had 7-16 connectors. A lot of the cellular equipment is 7-16, too.
A lot of it comes down to power handling capability and PIM. N's work great in lower power applications, 7-16 are pretty popular for higher power applications. Still a number of BNC out there for our receiver multicouplers.
Of course Motorola loves the "mini-UHF" on their mobiles, including gear up in the 900MHz range.

We use a lot of Kenwood mobiles at work. The VHF radios use UHF, all the 800MHz radios use N.

 

[krokus]

There is an added benefit with N connectors, when installed properly, they are water resistant. They are not any more difficult to install, once you learn how to do it.

 

[SpectrumAnalyzer]

N vs SO-239

Okay gent's so the bottom line is SO-239 connectors will not have a negative impact like diminished reception on coax used for 25 MHz to 1,300 MHz DC to daylight receivers, thanks all for your input & enjoy the rest of the weekend.

 

[Voyager]

What replies were you reading? Not one said they would work without diminished performance above 500 MHz. In fact, several said they would, and that an N connector is the connector of choice. BNCs will even be better than UHF connectors. The latest common commerical connector is a DIN.

Add me to those experienced with poor performance at 800 MHz and above for UHF connectors.

 

[teufler]

YEARS AGO, I took a kenwood 7400, replaced the s0239 with a n connector. Course had to redo the coax to the antenna . I did notice an increase in output from 30 watts to alittle over 35. Just experimented but did get a 10% gain in output probably due to better transfer of rf energy. Now the gain was hardly noticed on my signal but N connections showed a higher transfer of rf energy.

 

[mmckenna]

Okay gent's so the bottom line is SO-239 connectors will not have a negative impact like diminished reception on coax used for 25 MHz to 1,300 MHz DC to daylight receivers, thanks all for your input & enjoy the rest of the weekend.

If you are using a consumer grade receiver, low end coax and an "all band" scanner antenna, I doubt you'd notice a difference. If you were using a high end receiver, 1/2 inch or better coax over a long run, and a good high gain antenna, yeah, you'd probably notice a difference.

It really comes down to keeping this a hobby or not. You can chase 0.1dB of loss around in circles, but the truth is most hobbyists with consumer gear wouldn't know a decibel if it came up and bit them on the rear.
If you are building out a new system, absolutely, go with "N" or "BNC" connectors on everything and ditch the UHF connectors. However if you've got 100 feet of RG-58, a rusty old 1970 scanner antenna duct taped to your chimney and a consumer grade radio, swapping out all your UHF connectors for N probably isn't going to result in anything noticeable.

In other words, swapping out your connectors without changing anything else is going to be pretty much pointless. Use what you've got and what you can afford. If you've got a wad of cash burning a hole in your pocket, then go for it.

 

[SpectrumAnalyzer]

It Was A Faux Pas

What replies were you reading? Not one said they would work without diminished performance above 500 MHz. In fact, several said they would, and that an N connector is the connector of choice. BNCs will even be better than UHF connectors. The latest common commerical connector is a DIN.

Add me to those experienced with poor performance at 800 MHz and above for UHF connectors.

My sincerest apologies if my comment irritated you in any way but a misspelling occurred & the time limit to reconfigure my post had long expired, either way all that you said is academic now because while you were posting your comment, irregardless of my mistaken comment I did clearly understand what the helpful members said & I already acted on good advice & had all the SO-239 connectors replaced by N connectors on my equipment & just now returned to the forum to let all that wished me well in my endeavor that my equipment should suffer no ill effects with the upgraded N connectors, again thanks all & enjoy the rest of the weekend.

 

[mmckenna]

So, did you notice a difference when you changed out the connectors?

 

[SpectrumAnalyzer]

All New Equipment, Well almost All Are New

If you are using a consumer grade receiver, low end coax and an "all band" scanner antenna, I doubt you'd notice a difference. If you were using a high end receiver, 1/2 inch or better coax over a long run, and a good high gain antenna, yeah, you'd probably notice a difference.

It really comes down to keeping this a hobby or not. You can chase 0.1dB of loss around in circles, but the truth is most hobbyists with consumer gear wouldn't know a decibel if it came up and bit them on the rear.
If you are building out a new system, absolutely, go with "N" or "BNC" connectors on everything and ditch the UHF connectors. However if you've got 100 feet of RG-58, a rusty old 1970 scanner antenna duct taped to your chimney and a consumer grade radio, swapping out all your UHF connectors for N probably isn't going to result in anything noticeable.

In other words, swapping out your connectors without changing anything else is going to be pretty much pointless. Use what you've got and what you can afford. If you've got a wad of cash burning a hole in your pocket, then go for it.

Nothing's hooked up yet, can't do anything until I get the antennas & then I still have to have the code enforcement officer look over the antennas & submit a letter for HOA approval.

A couple of new UHF VX-5500's & a vintage Yaesu VR5000 that I think is worth it, some 20' lengths of Andrews 1/2" Superflex heliax & some antennas not decided on yet, the old stuff goes to my grandson who is hooked on scanners & what he can hear on them, have a good one & thanks.

 

[mmckenna]

Sounds like a pretty good setup. Maybe when/if I retire I'll build out a system at home.

Awful nice of you to pass your old gear down to your grandson. I'm sure he'll appreciate that. My grandfather passed down an old tube shortwave receiver to me when I was young. We put new capacitors in the power supply and it was good to go.

 

[prcguy]

There are different grades of PL-259/SO-239 connectors and the silver plated Teflon types are not that bad through 500MHz.

Take the Motorola T-1504A UHF duplexer for example, it has four cavities and four interconnect cables, all PL-259 type. The insertion loss at 500MHz is rated at 1.3dB and that would be for two of the cavities, two cables with four SO-239s, five PL-259s and an SO-230 Tee adapter in the circuit.

The two cavaties have about .25dB loss each for the pair being .5dB, leaving the remaining .8dB loss spread out over the four SO-239s, five PL-259s and the Tee adapter. Breaking that down to five connections would make it about .16dB per SO-239/PL-259 connection or maybe .08dB per connector and that's at 500MHz. Somebody please check my math but that's not enough loss per connector to worry about in most cases.

I would not use Chinese PL-259s or SO-239s with unknown specs above HF but have no problem using good quality silver/teflon connectors as used on the Motorola duplexer up through UHF.
prcguy

 

[Project25_MASTR]

Some T band equipment ships with N connectors. Mini-U is actually fairly stable up to around 1 GHz (I think that's the reason it's fairly standard on Motorolas). I don't really like using UHF on anything (I think it's easier to build BNC, mini-U and N depending on the connector pieces).

 

[zz0468]

A couple of things about the so-called UHF connector series...

A mated coaxial connector is actually a short piece of transmission line that comes apart. The physical dimensions of the UHF connector aren't sized to present a 50 ohm transmission line, so that creates an impedance bump where the characteristic impedance of the line is something other than 50 ohms.

Another thing is the materials used... The dialectic properties can change with frequency, and some materials used can be quite lossy at the higher frequencies.

If you play around with a Smith Chart, and insert a short piece of off-impedance transmission line into a circuit, you'll see all sorts of interesting results, especially as the physical length of the mismatch approaches a wavelength, or even just a significant fraction of.

This is the primary reason that UHF connectors give poor performance at higher frequencies. The random properties of some of the dialectic materials used is the other significant factor. Bakelite has poor insulating properties in the higher frequency range, but Teflon is excellent. That affects the characteristic impedance of the connector just as much as the physical dimensions do.

This is why the silver plated Teflon UHF connectors can be perfectly fine at 500 MHz, but the cheaper nickel plate Bakelite connectors are not.

For those of you who have access to a stock of crimp style male and female N connectors, take a set of male and female pins and mate them together. Look at the fit when the pins are fully mated together. It's a very precise fit, with an almost microscopic discontinuity in outer diameter. That close tolerance is essential to the N connector's performance at high frequencies, and that's where the N connector's "constant impedance" characteristic comes into existance. If you're not using a pin depth gauge to assemble your N connectors, you're probably doing them wrong.

 

[wirelesssamurai]

Larry Benko did some testing

A Look at the UHF Connector

his conclusions at the bottom of that page confirm what was posted above