Proxmark3 community

lockakey

Contributor

Registered: 2015-10-10

Posts: 22

LF 125 khz low voltage at Tune

Ive been here for quite some time, quietly learning.

My LF 125khz voltage started dropping recently, I noticed it last week at first.
Im getting 14-15v on the 125 khz side (not bad, but not the + 22v I was getting originally.)
The 134 khz side looks fine tho. bad divisor?

I figured it was a faulty antenna, I ordered a brand new one from rsyv. Same exact problem. Same exact results.
So Im ruling out that the antennas are good.
Is it a setting or did I fry something on the board?

How do I get that 125 khz up!

PS (just purchased an elechouse board, I ruled out the software client, maybe I need to update the pm3 flash on board? )

-Lockakey

proxmark3> hw version
#db# Prox/RFID mark3 RFID instrument                 
#db# bootrom: /-suspect 2015-06-23 13:21:04                 
#db# os: /-suspect 2015-06-23 13:21:10                 
#db# HF FPGA image built on 2015/06/22 at 21:47:54                 
uC: AT91SAM7S256 Rev A          
Embedded Processor: ARM7TDMI          
Nonvolatile Program Memory Size: 256K bytes          
Second Nonvolatile Program Memory Size: None          
Internal SRAM Size: 256K bytes          
Architecture Identifier: AT91SAM7Sxx Series          
Nonvolatile Program Memory Type: Embedded Flash Memory          
 
proxmark3> hw tune
Measuring antenna characteristics, please wait.........          
# LF antenna: 14.44 V @   125.00 kHz          
# LF antenna: 26.95 V @   134.00 kHz          
# LF optimal: 28.32 V @   131.87 kHz          
# HF antenna:  1.10 V @    13.56 MHz          
# Your HF antenna is unusable.          
Displaying LF tuning graph. Divisor 89 is 134khz, 95 is 125khz.
 
proxmark3> hw tune
Measuring antenna characteristics, please wait.........          
# LF antenna: 14.44 V @   125.00 kHz          
# LF antenna: 26.95 V @   134.00 kHz          
# LF optimal: 28.32 V @   131.87 kHz          
# HF antenna:  1.10 V @    13.56 MHz          
# Your HF antenna is unusable.          
Displaying LF tuning graph. Divisor 89 is 134khz, 95 is 125khz.
proxmark3> 

lockakey

Contributor

Registered: 2015-10-10

Posts: 22

Re: LF 125 khz low voltage at Tune

BUMP, still can't figure out why I'm getting low voltage on the 125khz with a brand new LF reader. Any help?

w106

Contributor

Registered: 2019-07-18

Posts: 6

Re: LF 125 khz low voltage at Tune

You can add more turns to your antenna, then you will get a higher voltage at 125khz but decrease the voltage at 134 khz. You can find a balance between them.
Sorry for my bad English.

iceman

Administrator

Registered: 2013-04-25

Posts: 9,537

Website

Re: LF 125 khz low voltage at Tune

Too little go to with.  But general recommendations applies.

1. compile / flash lastest official repo firmware
2. run client and see if something got better?
3. check hardware,  is something loose?
4. RMA from where you bought it?

Tom5ive

Contributor

Registered: 2017-09-18

Posts: 53

Re: LF 125 khz low voltage at Tune

Is this by chance a proxmark3 from eBay or the likes?

iceman

Administrator

Registered: 2013-04-25

Posts: 9,537

Website

Re: LF 125 khz low voltage at Tune

Like Tom5ive suggest,  it its a cheap clone from alixpress, wish, eBay you might have a hardware problem aswell..