Author Topic: Chinese Terminator  (Read 4049 times)

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Offline mnementh

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Re: Chinese Terminator
« Reply #25 on: December 22, 2017, 04:30:10 am »



Sure, but a single SMD resistor terminator can be assembled with a single touch of a soldering iron and it still performs better at 26.5GHz than the axial performs at 2.5GHz. I just tried it; see attached.

EDIT: The aliexpress prices are of course a better reflection of manufacturing cost, but they too reflect a cheaper SMD version. It's a little cheaper and a lot better.

I think you just found the Higgs Boson there...  :-DD


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Offline tautech

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Re: Chinese Terminator
« Reply #26 on: December 22, 2017, 04:57:14 am »



Sure, but a single SMD resistor terminator can be assembled with a single touch of a soldering iron and it still performs better at 26.5GHz than the axial performs at 2.5GHz. I just tried it; see attached.

EDIT: The aliexpress prices are of course a better reflection of manufacturing cost, but they too reflect a cheaper SMD version. It's a little cheaper and a lot better.

I think you just found the Higgs Boson there...  :-DD


mnem
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Nah, these are just learners compared to what GK has done:
https://www.eevblog.com/forum/projects/t20347/msg898898/#msg898898
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Offline mnementh

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Re: Chinese Terminator
« Reply #27 on: December 22, 2017, 05:14:45 am »
So what you're saying is... my [Random Mode] isn't nearly random enough?

[/Random mode]


mnem
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Offline Bud

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Re: Chinese Terminator
« Reply #28 on: December 22, 2017, 06:29:56 am »
This sort of crap is why I've started buying good quality cables and terminations.

You better do, because Chinese poorly mechanicaly made connectors can ruin your equipment connectors.
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Offline Mr. Scram

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Re: Chinese Terminator
« Reply #29 on: December 22, 2017, 08:06:08 am »
You better do, because Chinese poorly mechanicaly made connectors can ruin your equipment connectors.
I imagine they can, but do they do this enough to be a real problem?
 

Online blueskull

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Re: Chinese Terminator
« Reply #30 on: December 22, 2017, 08:10:17 am »
I imagine they can, but do they do this enough to be a real problem?

Not an issue for smart people. Smart people know not to force a connector into a 26GHz VNA or something.
For low frequency scopes and SA/VNAs (<5GHz for SMA, <2GHz for BNC), the connectors are pretty forgiving to mechanical abusing.
 

Offline jjoonathan

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Re: Chinese Terminator
« Reply #31 on: December 22, 2017, 03:54:29 pm »
Yep, it's a real problem. Tight tolerances, tiny delicate structures, and relatively large forces (8 in-lb) are a recipe for connector destruction. Cheap ebay equipment frequently comes with horribly chowdered up input connectors.

A slightly-too-long male pin will split a slotted female pin. A slightly-too-wide or burred male pin will catch a "finger" of the female pin and push it back. A female pin with bad edges will scratch up a male pin. Twisting the connectors during mating will occasionally catch the female fingers on the male pin, bending one and scratching the other. It will always cause abrasion, which is quite visible at 50GHz. I see three of these (too long, bad edges, abrasion) frequently. Pin width seems to be better controlled; my guess is swiss lathe programmers/operators tend to know what they're doing. Everyone blames connector failure on twisting-during-mating, but I privately suspect that this accounts for only a small fraction of ruined connectors.

The male SMA connector for the subject of this thread was almost 10 mil out of spec lengthwise in the bad, potentially harmful direction, FWIW. Good connectors are typically 1-2mil in the good direction. We can speculate about what it would have done to the precision slotless connector on my VNA had I attached it, but we will never find out :-)


EDIT: see the precision 3.5mm female conector here in all its glory: https://www.microwaves101.com/encyclopedias/how-to-not-trash-a-calibration-kit
« Last Edit: December 22, 2017, 04:03:33 pm by jjoonathan »
 

Offline mnementh

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Re: Chinese Terminator
« Reply #32 on: December 22, 2017, 05:02:26 pm »
Yep, it's a real problem. Tight tolerances, tiny delicate structures, and relatively large forces (8 in-lb) are a recipe for connector destruction. Cheap ebay equipment frequently comes with horribly chowdered up input connectors.

A slightly-too-long male pin will split a slotted female pin. A slightly-too-wide or burred male pin will catch a "finger" of the female pin and push it back. A female pin with bad edges will scratch up a male pin. Twisting the connectors during mating will occasionally catch the female fingers on the male pin, bending one and scratching the other. It will always cause abrasion, which is quite visible at 50GHz. I see three of these (too long, bad edges, abrasion) frequently. Pin width seems to be better controlled; my guess is swiss lathe programmers/operators tend to know what they're doing. Everyone blames connector failure on twisting-during-mating, but I privately suspect that this accounts for only a small fraction of ruined connectors.

The male SMA connector for the subject of this thread was almost 10 mil out of spec lengthwise in the bad, potentially harmful direction, FWIW. Good connectors are typically 1-2mil in the good direction. We can speculate about what it would have done to the precision slotless connector on my VNA had I attached it, but we will never find out :-)


EDIT: see the precision 3.5mm female conector here in all its glory: https://www.microwaves101.com/encyclopedias/how-to-not-trash-a-calibration-kit

Yeah, but SMA/RP-SMA are WAY overused in many applications where frequent connection/disconnection is part of normal service. Depending on the manufacturer, most are rated at only 200-500 mating cycles; I understand there are some all SS variants rated for more, but they are frightfully expensive.


mnem
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Offline Mr. Scram

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Re: Chinese Terminator
« Reply #33 on: December 23, 2017, 05:47:09 pm »
My mistake, I thought we were talking about BNC connectors too.
 


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