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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 A week ago

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 A week ago

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 A week ago


... 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 A week ago

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 A week ago

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:
Wonko

#6 ambralivio

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Posted A week ago

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 A week ago

@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 A week ago

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 A week ago

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 A week ago

@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 A week ago

...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 A week ago

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 A week ago

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 5 days ago

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 4 days ago

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...






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