Disable PTT stops TX, but still no RX

[Lionel Mesguen]

Hi,
I have just received the equipment from MarkerFabs (Hermes Lite 2, Filter Card, and IO Card).
I assembled everything without any difficulty, including soldering the 3-pin header and mounting the heatsink with the thermal pad.
The Hermes Lite board is properly detected on my LAN, and the antenna I am using works fine with another transceiver.
However, with Thetis HL2 (v2.10.3.12), as soon as I switch to RUN, the Hermes Lite goes into transmit, even though VAC1 and VAC2 are disabled and no VOX also.
If I enable Disable PTT, the unexpected transmit no longer occurs when I switch to RUN.
However, I do not understand why PTT was being triggered in the first place, because  nothing is connected to the Hermes Lite 2 except the antenna, the Ethernet cable and the 12 V power supply.
I removed the IO Card, but that did not change anything.
So at this point, it seems that some hardware PTT input may be active even though nothing external is connected.
I still have the other problem as well: I am still getting no receive at all. I also tested it with SDR Console, and there is no reception there either.
I also wanted to mention another point: in RUN / receive mode, the unit becomes relatively warm. In Thetis, I can see about 1.2 A current draw and around 55°C. This seems quite high to me for receive-only operation.
Could you please help me and let me know what procedure I should follow ?
Lionel - FG5EX

[brhl...@gmail.com]

in rcv its about 250mA and Temp 30 °C.Try without the enclosure and without heatsink. 

[Lionel Mesguen]

Hi,

For your information, I am getting back to you regarding the transmit issue that occurs as soon as I put the new Hermes Lite I received into RUN mode. 

I have now completed additional checks and the problem appears to be a reproducible hardware fault on the CW/PTT input of this new Hermes Lite 2.

Note: for the voltage the IO Board was removed.

With nothing connected to the CW/PTT jack:

    the HL2 enters transmit when RUN is enabled
    DB1 pin10 = 3.23 V
    DB1 pin12 = 0.84 V


According to the schematic, pin10 and pin12 should both be pulled up to 3.3 V. Pin12 is abnormally low, which explains the false TX triggering.

Lionel - FG5EX

[Pascal PBY]

Bonjour Lionel,

J'ai en moyenne 30 degrés en RX mais il vrai que la température ambiante n'est pas la même que chez vous. Par contre en RX j'ai 0 ampères, ça monte uniquement en TX...

73,

F6HCM, Pascal

>>> Envoyé depuis un Google Pixel

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[Steve Haynal]

Hi Lionel,

What is the 3-pin header you soldered on?

At pin12 of DB1 with no power connected, what resistance do you measure between pin 12 and +3V3 and also between pin 12 and GND? This is to determine if the problem is an open to +3V3 or short to GND. You can find voltage measurement points here:

https://github.com/softerhardware/Hermes-Lite2/wiki/Hardware

73,

Steve

kf7o

[Steve Haynal]

Hi Lionel,

Posting your private response below.

Hi Steve,

The values measured with the ohmmeter depend on the connection polarity.

Ohmmeter + / Ohmmeter -
pin12 / 3.3V = 1.45k
3.3V / pin12 = 1.21k
pin12 / GND = 1.49k
GND / pin12 = 0.93k

For comparison with the other input (pin 10), which does not present any issue:

Ohmmeter + / Ohmmeter -
pin10 / 3.3V = 2.21k
3.3V / pin10 = 2.20k
pin10 / GND = 3.05k
GND / pin10 = 2.95k

73
Lionel FG5EX

Did you connect anything to CN4 before this problem occurred? I am checking for damage due to a bad external connection.

Also, can you please inspect closely (bright light and magnifying glass) if there are any shorts between the trace going to pin 12 and other traces. The picture below shows the traces in that area. In particular, you can see that the trace for pin 11 goes very near pin 12. Also, at a via the pin 12 trace is close to the pin 9 trace. You may be able to visually see a short or measure one with an ohmmeter.

When did you purchase your HL2?

Here is the lower portion for the continuation of the 2 thick red pin 10 and 12 traces going down.

73,

Steve

kf7o

[Lionel MESGUEN]

Hi Steve,

I bought the equipment online on March 19, and I received it on March 30.
I reported the problem to Markerfabs and in the Hermes-Lite group on April 1.
I have never connected anything to CN4.
Regarding the requested measurements:

Ohmmeter + / Ohmmeter -

pin12 / pin11 = 5.42M
pin11 / pin12 = ∞
pin12 / pin9 = 541M
GND / pin12 = ∞

I took a few photos of the PCB but did not see anything abnormal.

73
Lionel FG5EX

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[Lionel MESGUEN]

Hi,
I made a mistake in my previous email about the last measurement.
The correct last measurement is:

pin9 / pin12 = ∞

and not:

GND / pin12 = ∞

73
Lionel FG5EX

Le 07/04/2026 à 00:40, Steve Haynal a écrit :

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[Steve Haynal]

Hi Lionel,

I've requested that Makerfabs proceed with a warranty exchange. You should receive private e-mail.

73,

Steve

kf7o