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Where to buy USB Y cable for Alfa USB wifi adapter?


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#1 AnonVendetta

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Posted 04 February 2019 - 11:16 AM

OK,so this isnt a booting question, but this is a technically inclined community, so I figure that someone here will know where to look:

I have an Alfa USB wifi adapter with several antennas, which is mainly designed for penetration testing. But in all the times I have tried to use it with Windows/Linux, it frequently disconnects. I recently posted about this on the Hak5 forum and they suggested that the device isnt getting enough power from the USB ports. I only have USB3/USB C ports, but this adapter is capable of drawing upwards of 2000mW. I'm not sure that even USB3 can provide that much power. They said I need a powered USB Y cable. The connector on the adapter looks identical to the power connector on old flip phones, before Android and MicroUSB/USB C. I'm not sure what it's called. Does someone here know where to find a USB Y cable that will work?

Thanks!

#2 Wonko the Sane

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Posted 04 February 2019 - 12:14 PM

Something doesn't match/compute.

https://en.wikipedia...er_and_charging

 

A USB 2.0 port maxes at 500 mA (per specs[1]), so a Y cable will deliver at most 1 A.

A USB 3.0 port maxes at 900 mA (per specs[2]) so a Y cable will deliver at most 1.8 A.

 

BUT 2000 mW is 2 W i..e. 5V * 0.4 A or 400 mA, even taking into account a cosFi of 0.9, you are still 2/(5*0.90)=0.444 A or 444 mA within the normal specifications of a single USB 2.0 port.

 

IF the reference is instead 2000 mA, i.e. 2 A, not even a Y cable is good enough (at least in theory, as often in the real word ports may provide more power than specs), and you'd be much better off with an appropriate power supply (or power bank).

 

A USB 3.1 port might do, but ONLY if the device can set it in the "right" mode[3].

 

Anyway you can try using a generic Y cable with two A males and an A female, using your existing cable that has a *whatever* connector (probably a mini or micro USB) and a standard A male, *like* (example):
https://www.ebay.com...y-/261292328894

 

:duff:

Wonko

 

 

 

 

 

 

[1] though very often this is exceeded and usually on modern motherboards 600 mA or so can be drawn

[2] some USB 3.0 ports do allow "charging mode" that is up to 1.5A or even 5 A,

[3]and USB 3.1 even more, but the mode is "negotiated" on the bus, and all in all it is a "mess":

https://en.wikipedia...r_Delivery_(PD)



#3 alacran

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Posted 04 February 2019 - 05:59 PM


... even taking into account a cosFi of 0.9,....


:duff:

Wonko

 

JFYI CosFi only apply when you are dealing with AC, (usually sinusoidal waves), never on DC or CC, and USB ports ARE NOT AC devices.

 

So according to WSB 2.0 specs single USB ports are delivering 5V * 0.5 A = 2.5 Watts = 2500 mW

 

If device specs require 2 W (2000 mW), there is no need for any additional Y cable, unless original cable is damaged. It may be no external signs of damage and have intermittent connection, but a new cable just like the original will solve the problem.

 

alacran



#4 ambralivio

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Posted 04 February 2019 - 06:30 PM

JFYI CosFi only apply when you are dealing with AC, (usually sinusoidal waves), never on DC or CC, and USB ports ARE NOT AC devices.

 

 

Correct!!!

 

Even if, working with USB implies that output voltage is fixed (5V) and so only output current max ratings are important.



#5 Wonko the Sane

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Posted 04 February 2019 - 06:33 PM

JFYI CosFi only apply when you are dealing with AC, (usually sinusoidal waves), never on DC or CC, and USB ports ARE NOT AC devices.

I know :smiling9:

I wanted to check if you were attentive.

@ambralivio
But not amymore with USB 3.x and USB C, now you can have 5/9/12 or 20 V. :ph34r:

:duff:
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#6 ambralivio

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Posted 04 February 2019 - 06:44 PM

But not amymore with USB 3.x and USB C, now you can have 5/9/12 or 20 V. :ph34r:

Well, NO if you want to preserve the important aspect of backward compatibility.



#7 AnonVendetta

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Posted 05 February 2019 - 03:44 AM

@Wonko: The adapter I have is Alfa AWUS036NHA. Some websites mention 1000mW, others 2000mW, so I went with the higher number. And most of the guys at Hak5 agree that it can reach 2000mW under heavy load, this is not your normal WLAN adapter designed for Internet surfing, downloads, streaming, etc. Though it can of course be used for those things.

 

As for the numbers and other lingo being mentioned.....f*****g Greek. It's like trying to speak English to an alien.

 

I have 5 USB 3.1 SuperSpeed ports, and 2 Thunderbolt/USB C. No 2.0 on my laptop. The adapter uses a mini USB connector.

 

@alacran: I'm sure the original cable isn't damaged, I haven't used this adapter alot since buying because of the disconnects. You cannot even do a small download or a speed test without it DCing. Regardless of OS. Linux supports this adapter pretty well, every distro I've tried recognized it immediately. It doesn't have any Windows 10-compatible drivers, but you can install the Win7 drivers from the disc in compatibility mode, it is recognized after rebooting.

 

I found this, they are authorized Alfa distributor:

 

https://store.roklan...-usb-mini-cable

 

But I'm sure it's just a plain old Y cable except much longer than the average Y cable.

 

After article on Rokland's website says that a Y cable shouldn't be needed on a modern PC, only on older PCs.



#8 Wonko the Sane

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Posted 05 February 2019 - 12:25 PM

Well, it is a sort of greek that is translated.
USB 2.0
5*400=2000
5*500=2500
2500>2000 you need NOT a USB Y cable

USB 3.0
5*400=2000
5*900=4500
4500>2000 you need NOT a USB Y cable

USB 3.1
5*400=2000
5*1500=7500
7500>2000 you need NOT a USB cable

BUT IF the computer/device you draw your power from does not respect the above standards, THEN you might need a USB Y cable, in which case you can use a "universal" Y cable, i.e. a USB Y cable extension, that draws power from two USB A males and has a USB A female at the other end, like the example you were given. (this way, even if it is not needed for this specific use, you can use it for other projects devices).

Getting a new USB cable USB A male on one end and the *whatever* the device has (which likely is a mini or micro B , find it here:
https://en.wikipedia...cal)#Connectors
is anyway a good idea to exclude that the issue is with the current cable.

:duff:
Wonko

#9 Rootman

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Posted 05 February 2019 - 05:07 PM

OK, I say skip the Y cable and get a powered USB 3.1 hub.  This would supply enough power and completely eliminate your USB ports as being the issue as far as insufficient power.  If your device still disconnects I'd say it's a sure bet that power is not the issue. 



#10 AnonVendetta

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Posted 06 February 2019 - 05:24 AM

@Rootman: The only problem with all this is that if I have to get a powered hub, then my setup isn't truly portable. My laptop has enough USB ports for me, I don't feel that I need a hub to provide more. Furthermore, I only need this for one item, most of the powered hubs I'm seeing have way more ports than I'll ever use, and are more expensive than I'd like to pay.

 

@Wonko: Others are recommending a Y cable, but by your estimates I don't need one (your numbers are still Greek to me, math has never been my strong point). I can only find one thing wrong with the ad you linked.....the seller doesn't list the length. But it's hard to beat free shipping. And the fact that there is a piece of tape in the center holding it together indicates that it is probably at least 6ft.

 

For now I'm getting:

 

https://www.amazon.c...DKIKX0DER&psc=1

 

I'd like to rule out, or not, that the original cable isn't faulty.

 

And I'm getting the Y cable Wonko linked, as you said it is still useful for other projects regardless. I think of a few usage scenarios with my Raspberry Pi.

 

The Rokland Y cable I linked looks nice, but it has a mini USB connector on one end, making it useless for any other device which doesn't have this input. I bought the Alfa from Rokland, since they are an authorized distributor. There are alot of fakes out there, so I decided to go with a reputable seller that Alfa trusts. It is possible that the device itself is defective, but I doubt it. There are other posters out there who also complained that the adapter DCs frequently.

 

Once I have tested those then I can further diagnose the issue.



#11 ambralivio

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Posted 06 February 2019 - 09:27 AM

...The only problem with all this is that if I have to get a powered hub, then my setup isn't truly portable. 

What about a battery pack (capable of up to 2A output current) then, to preserve portability ?

And referring to portability, a battery pack is always useful for thousands other uses...



#12 Wonko the Sane

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Posted 06 February 2019 - 12:45 PM

Well, now that we are a into a guessing game, I can express my personal opinion.

A cable can be:
1) healthy (working fine)
2) bad (NOT working)
3) intermittently bad
4) bad in a way to limit the current that goes through it

While it is theoretically possible that #4 applies, it would be an extremely remote case, that I would rate as 0.001% of cases (it basically means that the cable is interrupted or completely misses insulation in some parts AND somehow formed some oxide or *whatever* that effectively works as a resistor/capacitor/whatever capable of reducing the current throughput while keeping the voltage high enough).

Since there is no particular "electronic negotiation" on a "plain" USB 2.0 cable, if the case is #2 or #3 the Alpha thingy would simply be NOT powered up.

Now, if I were you I would invest a few bucks into a USB voltmeter/ammeter, examples:
https://www.ebay.com...r-/311875430396

So that you can check what the port and device actually (respectively) can provide and absorb.


:duff:
Wonko

#13 cdob

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Posted 06 February 2019 - 09:51 PM

The adapter I have is Alfa AWUS036NHA.der PCs.

I bought the Alfa from Rokland


https://en.wikipedia...er_power_output

https://wikidevi.com...work_AWUS036NHA

FCC test results
Output power (before antenna): 10.41 dBm peak (802.11b CH6) (10.99mW)

The output power is 11mW by default.

Do you use special country settings?
https://forums.kali....php/t-4129.html

Yes, meassure both input ampere and volts.

#14 AnonVendetta

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Posted 12 February 2019 - 05:54 PM

I just got the USB Y and mini-USB cable delivered this morning, I will try them out later today and report on the results. I also have a 20000mah portable battery pack which has 3 USB inputs and can output varying amounts of power on each of those ports, will test with that too. I only use it for powering my Raspberry Pi on the go but maybe now it has a 2nd use. I think it might suffice in the place of a powered USB hub. I also am considering placimg am order for the ampmeter/voltmeter, but eBay says "The seller is away" so I have no idea when it would arrive. I am just now getting situated in the new apartment I have moved into, so I havent had alot of time to practice my hobbies.

#15 ambralivio

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Posted 13 February 2019 - 08:57 AM

I also have a 20000mah portable battery pack which has 3 USB inputs and can output varying amounts of power on each of those ports, will test with that too. I only use it for powering my Raspberry Pi on the go but maybe now it has a 2nd use. 

@ AnonVendetta

I'm seeing that finally your're following the advices about battery pack ...

Also the usb multimeter tester is very useful (for different aims), but please consider they all have only USB type-A I/O's, so you need suitable USB adapters in case of other USB connection types...



#16 AnonVendetta

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Posted 18 February 2019 - 12:09 AM

I suppose I can end my investigation now, maybe. With the AmazonBasics Mini-USB to USB male cable I bought, there are no disconnects. So far I have tested with pinging, plain old Web surfing, doing a few speed tests, downloading large files via HTTP/HTTPS, and torrenting. I was able to download Grand Theft Auto V, a 80GB game, from my Rockstar Social Club account, in about 2 hours for download/install time, and it seems there were no disconnects at any point. I was also getting max speed for most of the download.

 

I have yet to do more advanced tests, for what the adapter was designed for, since those things are mostly done in Linux and require advanced knowledge. I guess I should go ahead and install Kali Linux again so I can start learning in-depth. But I am also going to try things like packet capturing/sniffing with WireShark (which is available for Linux and Windows). You simply can't make the fullest use of this adapter in Windows, unless you only care about basic stuff like Web surfing, etc. But if that's your thing then you don't need this adapter.

 

But.....now I have a USB Y cable as well, not sure what to do with it. Trying to think of some use case scenarios. I suppose I can later test it with the adapter anyway. And I never bought the voltmeter/ampmeter since eBay listed the seller as being away, although I'm sure others sell something similar. It sounds useful so I'll probably get it soon.

 

As for my external battery with 3 USB ports, I suppose it can function in place of a powered USB hub. It is a Mophie 20000mah battery that I bought at Best Buy some months ago, mainly to power my phones when they need juice. But I also ocassionally use it as a power source for my Raspberry Pi, when I'm not near an AC outlet. The USB outputs are as follows:

 

1. 1.0A

2. 2.1A

3. 2.1A, with a pic of a battery and a lighting symbol inside it, with left/right arrows going both ways horizontally thru the center, which I think mean high speed/SuperSpeed/Quick-Charge compatible.

 

There is also a Micro USB input port for charging the battery. Link:

 

https://imgur.com/a/g8qpQ6V

 

What is the difference between the 2 2.1A ports?

 

Well, I guess for now I can rule out insufficient power from my laptops ports as being the culprit.



#17 AnonVendetta

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Posted 19 February 2019 - 01:38 AM

I suppose it also helps that the newer cable is noticeably thicker than the old one, indicating better insulation from outside interference. And the connector is gold-plated, but I doubt that helps much. I'm just surprised that a renowned manufacturer like Alfa shipped a good product but with a bad cable.....shit happens.
 
There are numerous drivers for Windows that this adapter can use, since it is based on an Atheros chipset. So far I've tried 2 different ones. The ones on the disc included with the adapter are for Win7, they install on Win10 with or without compatibility mode, but some users have reported better success by extracting the drivers from the disc and running the setup with Win7 compatibility mode. However, the ones on the disc are quite old, and some have reported frequent BSODs.
 
Rokland suggests using this one and says that it seems to be more stable, the blog entry was posted in 2018. That's what I'm going with, no issues so far:
 
 
This 2nd driver will also install fine with or without compatibility mode, but it also has an optional TP-LINK utility which will not install without compatibility mode. Seems pretty useful to me.


#18 AnonVendetta

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Posted 18 May 2019 - 09:53 PM

I just got this digital "multimeter", I guess you could call it, from Amazon:

https://www.amazon.c...ob_b_asin_title

It can measure USB C, MicroUSB, and USB. I'm not having issues with the Alfa anymore, it doesn't disconnect at all ever since I replaced the cable. But I'd still be interested to see how much power it uses.

Besides that, I have a few external power banks I'd like to do some tests on. As well as a extended internal battery for a phone. I'm interested to see if it actually does have the 11800mah capacity the manufacturer cites. I've only had it for a few days, so if the #'s don't come up anywhere near 11800, I'll be contacting them for an exchange. Other customers have said they have a generous return policy.

I did also get the USB Y cable as well, though I haven't found a use for it yet.

Now I just have to figure out how to use this thing.

#19 alacran

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Posted 18 May 2019 - 10:07 PM

Now I just have to figure out how to use this thing.

 

Use your imagination.



#20 AnonVendetta

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Posted 18 May 2019 - 10:12 PM

@alacran: Yeah, I know that part, goofus. Only a complete idiot would think they can stick their dick in there and get results. It's the measurement of amps/volts/ohms etc that might get confusing. Figuring out which #'s are relevant, correct, appropriate, etc.



#21 Wonko the Sane

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Posted 19 May 2019 - 07:53 AM

Well, you need a crash-crash course in basic electrical units and measurements then.

 

Easiest would be thinking of a water pipe. :w00t:

 

Volts is the pressure of the water.

Amperes is the size of the pipe.

Ah (Ampere per hour) is the amount of water that comes out of the pipe in one hour.

 

The thingy you bought can measure Volts and Ampere directly but you will need a constant current dummy load.

 

In order to measure capacity of a battery you normally monitor its voltage while connected to a constant load (typically a suitable load cell which is actually nothing but a resistor), there are of course dedicated instrumentation to do that, but is way off the reach of a hobbyist.

 

See:

https://www.electron...g-cell-capacity

 

You want to get one of these (example):

https://www.plexisho...-load-1-2a.html

or one of the more sophisticated electronic dummy loads like the "other" one seen here:

 

Or you can get a USB battery load tester which is a combination of what you already have with an electronic dummy load. like (again example):

https://www.aliexpre...2879781131.html

 

Check:

https://www.youtube.com/watch?v=r4wHZdDARvo

 

:duff:

Wonko



#22 steve6375

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Posted 19 May 2019 - 09:27 AM

Power loss through cables is quite common due to the use of thinner wires but you cannot assume that is the problem until you prove it.

Another common problem is electrical interference. USB 3 data signals (from other connected USB 3  devices) can interfere with 2.4GHz signals. A poorly constructed and shielded cable can make this worse.

So you should try both the 'good' and 'bad' cables with your WiFi dongle connected and measure the voltage as near to the WiFi connector as possible and compare the results.

Next, you should connect a USB 2 extension cable (NOT USB 3) to the WiFi dongle + bad cable and connect it up to the system as before. Does it still misbehave or does it work OK (just slower). Also measure the voltage as near to the WiFi dongle as you can.

 

Another test is to ensure that no other USB 3 device is connected to the laptop except for the WiFi dongle and see if that fixes the problem.

 

Read about my experiences with USB 3 and WiFI/Bluetooth here...

https://rmprepusb.bl...se-and-usb.html



#23 AnonVendetta

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Posted 20 May 2019 - 12:07 AM

I'm not seeing why a USB dummy load is necessary. The batteries (external) are either powered on or in use (inside the phone) so they should be drawing power on their own. Why is a dummy load needed?

 

The water pipe analogy helps somewhat, but not really, it does not help me understand whethe the devices are drawing their stated power or pushing/pulling the amount of power that they should be. Also, how would one go about testing a charger/cable to determine its' capacity?



#24 Wonko the Sane

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Posted 20 May 2019 - 09:47 AM

I'm not seeing why a USB dummy load is necessary. The batteries (external) are either powered on or in use (inside the phone) so they should be drawing power on their own. Why is a dummy load needed?

 

The water pipe analogy helps somewhat, but not really, it does not help me understand whethe the devices are drawing their stated power or pushing/pulling the amount of power that they should be. Also, how would one go about testing a charger/cable to determine its' capacity?

The dummy load is a constant load, you can use as a replacement any resistive load (say) a 2-5W 6-12V lamp.

 

Loading a battery (or the phone, etc.) implies variable amounts of current flowing.

 

You want to have a constant load (and thus a constant current draw) for simplicity. 

 

After having drawn - say - 1000 mA for 5 hours the voltage drops down to around 70%-75% of what was when the battery pack was fully charged (roughly EODV), and the (approximated) calculation is:

1000*5=5,000 mAh

 

If you prefer, you are calculating the area in green on this graph:

https://www.electron...7Zollo_Fig1.gif

 

If you don't have this constant current draw, you would need more data points (please read as need to log a read every - say - 15 minutes) to integrate the non-linear graph area and the measure would be anyway less accurate.

 

:duff:

Wonko






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