DIY LF antenna for Proxmark 3 Easy

[NiamhAstra]

So are you going to make a DIY HF antenna next?

[Compgeek]

I probably won’t, the HF chips that I work with don’t seem to have the tearing issue so it doesnt seem as critical.

Plus, on the PM3 easy, the HF antenna is ‘non removable’ - so it’d be a bit of time with a dremel and figuring out a good way to add a connector to do it. Plus then building a new ‘non implant’ antenna for it too

[Nimus]

This is probably a dumb question but would a 10mm ferrite rod work fine? There are plenty of listings for 10mm ferrite rods but I can’t find many (affordable) 9mm ferrite rods.

[Compgeek]

I think mine was 9.5 - don’t think 10 would be an issue, go with what you can get!

[Eriequiet]

Sigh… I might undertake this project also
But I’m also not entirely sure my proxmark is even installed correctly… and I’m missing a side plug the prox easy is supposed to have

Half tempted to just buy a rdv4

[Pilgrimsmaster]

@Eriequiet

I’m missing a side plug the prox easy is supposed to have

I think there are 2 versions
If you have a look at the commonly linked to PiSwords one, there is

“Bundle one” which has 2 USB Ports:(one is for powerbank, another can be off-line sniffing) and “Bundle two” which has 1 USB port

[anon3825968]

@Eriequiet

Half tempted to just buy a rdv4

That’s kind of why I went straight for that one: I had a feeling it’s one of those things you end up buying anyway in the end because it’s just plain better, and you regret blown money on the inferior version of.

[Eriequiet]

@Pilgrimsmaster

I think there are 2 versions
If you have a look at the commonly linked to PiSwords one, there is

“Bundle one” which has 2 USB Ports:(one is for powerbank, another can be off-line sniffing) and “Bundle two” which has 1 USB port

Yea I bought from piswords, apparently I got bundle 1

So I can’t find any other information on what the various light configurations mean, I can tap or hold the button and the light changes to various colors or posistions

Super lost on it if I’m being honest even though I managed to clone my prox work badge to a generic 125khz card

[Blu3Rats]

@Eriequiet

So I can’t find any other information on what the various light configurations mean, I can tap or hold the button and the light changes to various colors or posistions

This may help scroll to the bottom there are video links

RfidResearchGroup/proxmark3

[Eriequiet]

Ok well I finally got my pm3 installed thanks to some help from darthdomo

Now to start looking at making an antenna

[Eriequiet]

Just a thought… before I commit to a build

Could I buy the prox lf antenna for the rdv4 and gut the antenna from it?

Might be easier / cheaper than building from scratch

[DonFire]

Apparently the main issue is that the rdv4 has all of the tuning circuitry on the antenna boards, allowing for very weird designs, whereas previous versions of the Proxmark 3 have on board fixed tuning circuitry that means that rdv4 antennas aren’t compatible.

See here for a better explanation:

ProxLF coil question

There’s one more wrinkle though… the RDV4 modular system puts the tuning caps on the antenna not the main board… this allows for different performing antennas to be made and easily swapped out, while the rdv2 has it’s tuning caps on the main PCB… so if your rdv2 antenna did have an inductance of 203μH you would still not be able to drop the ProxLF on the rdv2 because the caps on the proxLF antenna itself would change the total capacitance involved and skew the required inductance to match up at …

Here is someone else who tried what you’re proposing without modification:

Proxmark LF Antennas

Has anyone attempted to connect this to other Proxmark3’s? I ended up ordering the wrong device, I think it’s actually a Proxmark3 Easy. I removed the stock LF antenna, and using low-quality jumpers I wired up the three terminals on the antenna sold here and got these numbers: Measuring antenna characteristics, please wait......... # LF antenna: 10.31 V @ 125.00 kHz # LF antenna: 10.86 V @ 134.00 kHz # LF optimal: 21.17 V @ 196.72 kHz # HF antenna: 28.86 V @ 13.56 MHz Display…

(my understanding of antenna design would suggest that if you could figure out / measure the value of the tuning caps on your easy, you might be able to counteract them with other passives, but working out what works best could be very difficult) - you can see a test board by the designer of the ProxLF with multiple values for tuning here:

Proxmark LF Antennas

This is well underway and the proxmark team and I have been smashing through the final stages of the design. Things were slightly delayed due to life getting in the way a little on my end. I’ll try and update the community soon with some preview pics asap! The final coil design is nothing short of amazing and I have tested it like mad. Here is a sneak peek at one of the coil test rigs (the final design will obviously be much neater - this board is purely for testing): [IMG_6236]

Hope this helped!

[Nimus]

I finally got the supplies in so I’m trying this out now. Unfortunately my PM3 Easy doesn’t even detect the antenna. I honestly have no idea what I’m doing so I’m just following what you guys did.

This is what I have:

When I run “hw tune” I get

[=] ---------- LF Antenna ----------
[+] LF optimal: 1832072.03 V -   0.00 kHz
[+] LF antenna is OK
[=] ---------- HF Antenna ----------
[+] HF antenna: 32.47 V - 13.56 MHz
[+] HF antenna is OK

[-] ⛔ Not showing LF tuning graph since all values is zero.

Is there something obvious that I’m doing wrong? I used superglue to hold the wire in certain spots but I tried to wipe up the excess. I also have about 20cm of extra wire on one end in case I needed more windings. The ferrite rod is cut to a little less than 3.5cm (since 2.5cm was too short for @Compgeek)

[Eriequiet]

Have you checked it for continuity? Could have a break in there maybe

[PaulT]

Sorry if this is obvious……. you’ve removed the enamel of the wire where it connects to your Proxmark PCB?

[Nimus]

@PaulT

Sorry if this is obvious……. you’ve removed the enamel of the wire where it connects to your Proxmark PCB?

Uhhh…I’ll be back for an update shortly…

[Devilclarke]

Hehe, thats the noob catch lol.

[Nimus]

Is this good?

[=] ---------- LF Antenna ----------
[+] LF antenna: 10.92 V - 125.00 kHz
[+] LF antenna: 11.34 V - 134.83 kHz
[+] LF optimal: 32.78 V - 218.18 kHz
[+] LF antenna is OK
[=] ---------- HF Antenna ----------
[+] HF antenna: 32.54 V - 13.56 MHz
[+] HF antenna is OK

[+] Displaying LF tuning graph. Divisor 88 is 134.83 kHz, 95 is 125.00 kHz.

Edit: Nevermind. I see that the “LF optimal” is what I should be looking at so 218.18kHz isn’t good.

[PaulT]

Well at least it’s working now Yeah it’s obviously high in frequency so you need more turns.

[Nimus]

Dang it! I ran out of space and I’m still not close to 125kHz

[=] ---------- LF Antenna ----------
[+] LF antenna: 13.35 V - 125.00 kHz
[+] LF antenna: 15.14 V - 134.83 kHz
[+] LF optimal: 40.67 V - 171.43 kHz
[+] LF antenna is OK

I have enough ferrite and wire to try another day.