RF connectors smack down ... AliExpress vs Amphenol

[BravoV]

N type male to male converter, just bought from AliExpress, 1st glance I didn't notice anything special, until I put both side by side with Amphenol, just look at the outer wall thickness.

[technogeeky]

Would the outer wall thickness have a major effect on the RF signal? Or would there just be a mechanical advantage?

[bd139]

That’s a great comparison. Cheap is cheap!

I buy amphenol BNC, SMA and SO239’s regularly and they are waaaay better than any of the generic and rebranded shit. No snagging or anything when you use them and they last a lot longer. I’ve actually noticed that cheap BNCs knacker test gear as well.

[BravoV]

Would the outer wall thickness have a major effect on the RF signal? Or would there just be a mechanical advantage?

I guess so, but not sure, lets hear from more experienced members. 

[BravoV]

That’s a great comparison. Cheap is cheap!

I buy amphenol BNC, SMA and SO239’s regularly and they are waaaay better than any of the generic and rebranded shit. No snagging or anything when you use them and they last a lot longer. I’ve actually noticed that cheap BNCs knacker test gear as well.

Agreed, some of my Amphenol BNCs treasure, bought few dozens of them NOS while ago, really good stuffs. 

[dmills]

Far more importantly compare the pin geometry.

[BravoV]

Far more importantly compare the pin geometry.

Yeah, I was wondering about that too.

Also Amphenol pin doesn't need the bling of golden plated look.

[Yansi]

That’s a great comparison. Cheap is cheap!

I buy amphenol BNC, SMA and SO239’s regularly and they are waaaay better than any of the generic and rebranded shit. No snagging or anything when you use them and they last a lot longer. I’ve actually noticed that cheap BNCs knacker test gear as well.

Yeaaah. That is nice if yo big daddy pays them for you.    $4 or more for a single PCB SMA termination won't happen, especially when I need tens of them for prototyping. 

[bd139]

$5 here. Worth it.

[dmills]

One thing to be most careful of with N types is that the 50 ohm and 75 ohm versions are NOT compatible, you will damage the female if you mate a 50 ohm plug into a 75 ohm female, and I think the two connectors shown by the OP may be different impedances (Specifically I think the Ali one may be 75 ohm).

Regards, Dan.

[rhb]

What's the VNA say?

[Monkeh]

One thing to be most careful of with N types is that the 50 ohm and 75 ohm versions are NOT compatible, you will damage the female if you mate a 50 ohm plug into a 75 ohm female, and I think the two connectors shown by the OP may be different impedances (Specifically I think the Ali one may be 75 ohm).

Regards, Dan.

I'm pretty sure they're both 50Ω from the pin diameter.

[xaxaxa]

The TE connectivity sma connectors from mouser are not bad (in terms of mating repeatability and return loss), and more reasonably priced; for non-production use there are reasonable quality ones on taobao (not aliexpress); look for ones that specify gold plating and in the price range of 3cny to 4cny each. I have measured these and up to 3GHz the difference in return loss compared to genuine ones is typically less than 0.1dB (the return loss due to pcb impedance error still dominates). I have also tested the gold plating with acid (the aliexpress ones failed horribly, but the TE and taobao ones held up).

[BravoV]

What's the VNA say?

Don't have VNA. 

[BravoV]

One thing to be most careful of with N types is that the 50 ohm and 75 ohm versions are NOT compatible, you will damage the female if you mate a 50 ohm plug into a 75 ohm female, and I think the two connectors shown by the OP may be different impedances (Specifically I think the Ali one may be 75 ohm).

Regards, Dan.

I'm pretty sure they're both 50Ω from the pin diameter.

Yes, both are 50Ω, I'm aware of 75Ω type as it has much much smaller pin, looks like needle when compared to 50Ω one.

[Wirehead]

Would the outer wall thickness have a major effect on the RF signal? Or would there just be a mechanical advantage?

I guess so, but not sure, lets hear from more experienced members. 

It does not. RF in coaxial connectors flows on the outer skin of the central conductor and on the inner surface of the outside shield.
The aliexpress connector could be just-as-good if you don't test it. This thread is pure FUD. 

[taydin]

Even if the wall thickness doesn't contribute to the signal integrity, the durability of a thicker wall would certainly make a difference when you drop it. Those things are heavy enough that when dropped from a few meters to concrete, the thin walled connector could lose its round shape.

I also suspect the Amphenol part is machined to tighter tolerances. If I had a $50,000 Keysight spectrum analyzer, I would DEFINITELY NOT insert a Chinese connector to it Even if the center pin is 0.03mm thicker than rated, it would widen the female inner connector and degrade it.

[rfspezi]

Even if the center pin is 0.03mm thicker than rated, it would widen the female inner connector and degrade it.

Oh comeon... you don't really beleave that the inner part of your spectrum analyzers female connector gets permanently widened from a 0.03 mm thicker male pin, don't you?

[hendorog]

Even if the center pin is 0.03mm thicker than rated, it would widen the female inner connector and degrade it.

Oh comeon... you don't really beleave that the inner part of your spectrum analyzers female connector gets permanently widened from a 0.03 mm thicker male pin, don't you?

Thats surely an exaggeration, but it might not take much. You can imagine that if the blunt ended pin got very close to the end of the 'hole' then a tiny additional diameter would force the fingers outwards.

[taydin]

Oh comeon... you don't really beleave that the inner part of your spectrum analyzers female connector gets permanently widened from a 0.03 mm thicker male pin, don't you?

If I had that SA, I would certainly not try to find out But in any case, with RF, contact quality makes a big difference. If you go to vendor's websites selling RF cables, you will find "precision" cables that are manufactured to much tighter tolerances, at a much higher price. Surely the buyers of those cables aren't the RF equivalent of "audiophools"

[Wirehead]

That's why you have "connector" savers.. Sacrificial 1:1 adapters.

As to dropping connectors: RF connectors are never made to be abused due to mechanical stress.
I'm still waiting on objective performance data. Not much of a smack down here.. 

[taydin]

That's why you have "connector" savers.. Sacrificial 1:1 adapters.

Ok, so you plug in an el cheapo 1:1 adapter into your 50K SA, which means, if that thing does not meet the tolerance requirements, it will have already damaged the SA's female connector. That kinda sacrificial 1:1 would ONLY make sense if it is a model that meets the precision specs, which means it would be a reputable brand 1:1

As to dropping connectors: RF connectors are never made to be abused due to mechanical stress.
I'm still waiting on objective performance data. Not much of a smack down here.. 

That's only in theory. When you are working at a cell tower in the middle of nowhere, and people expect you to get the job done yesterday, you would want a connector that survives minor OOPS'es, and not drive back to headquarters to get a new connector

But hey, you might be Mr Perfect who never OOPS'es, then this won't apply to you. But us mere mortals occasionally do screw up

[taydin]

Hopefully somebody with a VNA can compare this Chinese thing with a reputable brand adapter.

I already know first hand that the impedance characteristics of Chinese RF terminators are all over the place throughout their rated frequency rance, so I have reason to suspect that the cheap Chinese adapter will have similar shortcomings, but it would be nice to see it in actual measurement.

[StuUK]

mmmm, this thread is starting to sound a lot like audiophoolery...

[dmills]

Ok, so you plug in an el cheapo 1:1 adapter into your 50K SA, which means, if that thing does not meet the tolerance requirements, it will have already damaged the SA's female connector. That kinda sacrificial 1:1 would ONLY make sense if it is a model that meets the precision specs, which means it would be a reputable brand 1:1

Yep, but a reputable brand 1:1 is still VERY MUCH cheaper then sending a VNA back to Keysight/R&S/Copper Mountain to have the connectors replaced, and even a non preciosn one will save the wear on the connector.

Adding a hundred quid or so to the cost of a £50k instrument is hardly a big deal if it means you can avoid weeks of downtime while the thing is being repaired.

Regards, Dan.