Issue with HL2 with no rf output

[Enrico Tafuro]

Hi all,
I purchased a Hermes Lite 2 on November, mainly used for reception up to now. Recently, during my first TX tests, I encountered an issue that occurs only at transmission time, while reception continues to work correctly -

The issue involves no RF output power during transmission, along with relay chattering on the N2ADR board. The device has not been tampered with in any way.

Tests performed:

• Hard reset of the Hermes Lite 2
• TX Test done with Thetis HL2, SparkSDR, and SDR Console starting with a full settings reset - all the same result with all of them
• Followed the entire troubleshooting guide found here (software-related)
• Tests performed using a 50 Ohm dummy load during TX tests

What can I do to resolve this issue?

[Josh Logan]

What is the network path from the computer to the radio?

In SparkSDR does ep6 increase as you use the system?  Did you enable the PA?  What is the filter setup you picked?

73, KD7HGL
Josh

--
You received this message because you are subscribed to the Google Groups "Hermes-Lite" group.
To unsubscribe from this group and stop receiving emails from it, send an email to hermes-lite...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/hermes-lite/287a8692-dac2-4384-82b2-9048a33ec2a8n%40googlegroups.com.

[Enrico Tafuro]

Hi Josh,
  the network path to HL2 is:

PC (w/Win 11 Pro) --> 2 meters Cat 6E cable --> Gigabit Ethernet router --> 2 meters Cat 6E cable --> HL2

In SparkSDR indicators are as follow:

>> RX time:
fwd 0,000W
rev 0,000W
ep6 0
SWR 0,00
26,4C
0,0mA


>> TX Time with 50 Ohm dummy load (/when PTT button is pressed):
fwd 0,000W
rev 0,000W
ep6 0 (ever)
SWR reports dancing random values > 0 continuously up and down -
28,1C
1,4mA - 1,5 mA (pretty stable)

These last figures are reported the same for all TX modes in almost all bands.
SWR random values are pretty high - up to 30.
Not seen any change of ep6 meter in SparkSDR.
I confirm (and paid attention that) PA is enabled in all the SDRs I've tried.

Tried with all filters pre-configuration in SparkSDR (except empty J16) obtaining the same result.
In CW mode PTT button causes only a simple relay bouncing on/off -

Current level at power supply unit are:
250 mA at RX time
350 mA at TX time (only few 100mA more than RX)

Any idea ?

[Pibo - S58WW]

Do you have checked options on your Thetis?

73 Pibo S58WW

[Enrico Tafuro]

Hi Pibo,

  I'm using Thetis 2.10.3.7 (build HL2 from MI0BOT) and those settings are ticked correctly (so PA activated).

I've also started again from a scratch new settings database to make sure I've not messed up anything critical - I've named it "Debug" (so restarted over a clean and fresh default settings configuration).

Applied setup guide step-by-step at this link from page 6 to 12:
https://groups.google.com/group/hermes-lite/attach/2af95aa9a0ce0/Hermes_Lite_2_Thetis_Installation_and_3rd_Party_Apps.pdf?part=0.1

NOTE: Page 7 - Hermes Step Attenuator
Enable RX1 appears grayed to me - but ticked.
This section reports a red "adc linked" label -

Result: No output in any mode (also in FM where the carrier should push some output power - also if nothing stimulates the signal chain in the HL2/it should exclude other software-dependant variables).

Settings database is attached here for inspection - I've not touched anything else in Thetis.

Thanks

You received this message because you are subscribed to a topic in the Google Groups "Hermes-Lite" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/hermes-lite/hC3-d_fXPVA/unsubscribe.
To unsubscribe from this group and all its topics, send an email to hermes-lite...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/hermes-lite/ac40185d-aeda-4f82-9eca-d38f4fea59een%40googlegroups.com.

[Pibo - S58WW]

Enrico... SRI that I did not read your posts with full attention. It has happend to me before to forgot tick that two items. I did build 3 (three) HL 2 (+). Two for me and one for my friend. One I still have. I did not have that kind of issue. I just wanted to help. I hope that you will solve your problem. 73 Pibo S58WW

[Enrico Tafuro]

Hi Pibo,
  I sincerely thank you for your support - I know you're all here to help. Probably no inspection should be overlooked, as there are so many variables at play.
I'm feeling a bit discouraged because, despite numerous attempts, I haven't been able to transmit with the HL2 even once -

I just want to understand whether it's a hardware issue with the board or if there's something else I should consider before initiating a return request with Makerfabs.

Enrico

To view this discussion visit https://groups.google.com/d/msgid/hermes-lite/b207532e-72fc-4be1-87ca-960f1d6917d1n%40googlegroups.com.

[Josh Logan]

Please review
https://github.com/softerhardware/Hermes-Lite2/wiki/Repair

I would also suggest removing the board from the case and taking pictures near the PA chips (top and bottom).

Did you ever load the 10rx version of gateware, and not load the tx version after testing?

You can also disable the PA and test tx.  The power would be low, but that will bypass the 2 PA chips.

73, KD7HGL
Josh

To view this discussion visit https://groups.google.com/d/msgid/hermes-lite/CANqqnyzm1MFoajFeMRV7MsLNPKKSDG%2BHuR19wX%3Dbxk6aUoxhkQ%40mail.gmail.com.

[Enrico Tafuro]

Hi all,
just a quick update.

I followed one of the latest hints and removed the HL2 from the case, done tests "on the table" without the heat sink on the PA area.
I had applied a small drop of thermal paste (the kind used for microprocessors) between the heat sink and the PCB layer - I carefully removed it off and then cleaned the layers with isopropyl alcohol.

By doing this, I finally managed to transmit, reaching 6W of power in CW mode.
Reinserted the board in the case, again HF was stopped (now board is clean!)
After that I've repositionated the heat sink, using the "low profile" side in touch with the PCB - instead of the high one.
In this way I managed to trasmit again. Curious.

I plan to conduct further tests (now I can transmit!), but it's still unclear what aspect of the heat sink was preventing the HF emission.

I'll keep you updated as soon as possible.

For now, thanks to everyone for the advice!
73, Enrico
IU2UCH

[Ron Lewkowicz]

https://github.com/softerhardware/Hermes-Lite2/wiki/Final-Assembly

As noted some thermal paste is conductive and can short the board. Be careful of that.  Also note the correct installation of the heat sink to avoid shorts and damage to the board as noted.  Sounds like your board came through unscathed. This is good.

[Pibo - S58WW]

Be careful with shim!!

73 Pibo S58WW