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#1 2016-04-30 19:16:07

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> 

" There is an unarguable downside to unbreakable encryption " - Michael Hayden

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#2 2016-05-02 01:39:34

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?


" There is an unarguable downside to unbreakable encryption " - Michael Hayden

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#3 2019-07-18 11:55:35

w106
Contributor
Registered: 2019-07-18
Posts: 3

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.

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#4 2019-07-18 13:46:44

iceman
Administrator
Registered: 2013-04-25
Posts: 5,601
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?


If you feel the love,  https://www.patreon.com/iceman1001

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#5 2019-07-23 05:01:58

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?

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#6 2019-07-23 08:34:53

iceman
Administrator
Registered: 2013-04-25
Posts: 5,601
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..


If you feel the love,  https://www.patreon.com/iceman1001

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