Hermes lite bais fail

Robert Larivee

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Mar 28, 2026, 2:39:38 PMMar 28

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Hello, I recently purchased a Hermes Lite 2. This isn't my first purchase; the previous ones worked perfectly. I received the one I ordered recently, and everything seems to be working, but the bias is unstable. It constantly stays at 1825 mA. I'm using two recommended software programs, but I can't resolve the issue; they display an error. What can I do to fix this problem? I'm writing to you to start! Thank you in advance for your help.

Steve Haynal

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Mar 29, 2026, 11:25:19 PMMar 29

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Hi VE2KTF,

What two software programs are you using to measure the bias? Does the bias change when you adjust it via software and just not stick? I am trying to determine if it is a bias measurement problem or bias setting problem.

73,

Steve

kf7o

Robert Larivee

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Mar 30, 2026, 12:12:57 AMMar 30

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I am unable to adjust the bias of the Hermes Lite with either software; it always remains at 1825mA

Steve Haynal

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Mar 30, 2026, 12:16:38 AMMar 30

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SparkSDR. hl2setup_win

I am unable to adjust the bias of the Hermes Lite with either software; it always remains at 1825mA

Hi VE2KTF,

Please remove the HL2 from the enclosure and try again. This is eliminate shorts from the enclosure.

Please share pictures of the top and bottom of your HL2, especially around the hole which applies pressure to the board/enclosure heatsink. Damaged or stripped components in this area can cause the problem you are seeing.

Refer to the HL2 schematic found at:

http://hermeslite.com/

With a regular volt meter, what voltage do you measure at points bias0 and bias1? What is the low and high voltages for bias0 and bias1 and the min and max software adjustment settings?

73,

Steve

kf7o

Robert Larivee

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Apr 8, 2026, 10:51:55 PMApr 8

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voltage

-gate 2.20v

-drain 7.96v

IMG_0099.jpeg

Robert Larivee

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Apr 8, 2026, 10:52:31 PMApr 8

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IMG_0098.jpeg

Robert Larivee

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Apr 8, 2026, 11:45:00 PMApr 8

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specification for voltage

low voltage -gate-2.01-drain-7.21

high voltage -gate-3.29-drain-7.92

Le mer. 8 avr. 2026 à 22:52, Robert Larivee <ve2...@gmail.com> a écrit :

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Steve Haynal

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Apr 10, 2026, 12:17:18 AMApr 10

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Hi,

Thanks for the pictures. J31 on the bottom of your PCB has been stripped off, probably during assembly with heatsink. This is just a zero ohm jumper. Are you able to bridge this with a small bit of wire and some solder? This would explain your bias issues.

In the photo of the top of the board, I can't see B106 which is right next to the mounting hole between the two LDMOS devices. Please check if that is present as it can be stripped off too.

73,

Steve

kf7o

Robert Larivee

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Apr 10, 2026, 12:55:27 AMApr 10

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Thank you so much, I managed to link the two and it works perfectly. A huge thank you!