Stange behaviour: working only with low power output

[Jean-Baptiste GALLAUZIAUX]

After six months of inactivity I just started again my HL2, using Quisk (with WSJTX, JS8Call and FreeDV, CW and SSB) and SparkSDR (SSB, CW and FT8).

The first times I started to transmit the first two left Leds lighted steady, a relay clicked inside then clicked once more and the HL2 stopped transmitting with the Leds having this behaviour:

all OFF then ADC 100 steady ON during one second

then Run flashing fast, Tx flashing slowly, ADC 75 and 100 steady ON. No power output.

All softwares blocked and needing to be halted in order that HL2 returns to a normal state.

Today I tested again with a reduced drive leading to an output power under 2 Watt and I have no more problems, it seems that my HL2 does not any more transmit at its maximum power level of around 5 Watt but works nicely at 2 Watt!!!

I'm working in the South Pacific with high temperatures, high humidity and my HL2 remainded stored in such conditions (90°F or more, high humidity). Maybe this stange behaviour will fade out when my HL2 dries?

73 - Pierre - FK8IH

[Steve Haynal]

Hi Pierre,

What temperature does your HL2 report during transmit at 5W when this problem is seen? There is protection in the gateware that will disable TX if the temperature is too hot.

73,

Steve

kf7o

[Jean-Baptiste GALLAUZIAUX]

Steve, I have left my HL2 "ON" during the last 24 hours and things are improving a little. I just started a SSB transmission at full power with StarkSDR (drive set at 255) and the problem came back again, StarkSDR showing a temperature of 36°C ( 97°F) when it happened. When I started my HL2 for the first time after having stored it during 7 months it hardly worked: no CW, no FT8 a little SSB at reduced power, now it is working normally if I limit the power to less than ~2W (drive set to 200 with StarkSDR). 

I just tested it with SparkSDR on 20M - FT8: 

- with a drive of 200 it gives steadily 1.52W without problem, the temperature rising steadily over 100°F;

- with a drive of 205 it still gives 1.7W without problem;

- with a drive of 206 it gives 1.76W during less than 5 seconds then stops transmitting, the temperature being around 36°C (97°C).

I whall keep it ON in order to get some heat inside and perhaps dry it? Anyway it seems to be working normally now as a very QRP rig!

73 - Pierre - FK8IH

[Steve Haynal]

Hi Pierre,

It would be helpful to understand at which stage the problem is occurring. At full transmit drive, is there low/no power output from the AD9866, is the TX preamp not functioning or is the PA not functioning? If you feel up to the task and have an oscilloscope, you can trace the signal through the TX path according to the schematic found here:

 http://www.hermeslite.com/

Another thought that comes to mind is your power supply. Is it capable of supplying the required current at full TX power? Is the HL2 restarting when it doesn't transmit at 5W? You can measure the required voltages during transmit as described on:
https://github.com/softerhardware/Hermes-Lite2/wiki/No-Transmit

73,

Steve

kf7o

[Jean-Baptiste GALLAUZIAUX]

Hi Steve, Thank you for your answer. When returning from my 6 months travel, when replugging my stationI just plugged a 1A power supply, which I use for my iambic keyer to the HL2 and plugged my 3A power supply to the iambic keyer. I just reversed this now and now my Hermes Lite 2 is working nicely as it had always done before.

I checked the current drawn with max power (around 6 Watt) on FT8 mode with SparkSDR and it shows 1.6A. When setting the drive at 207 where my HL2 froze before the current draw is .890A but the 1A power supply is a very basic wall adapter power supply with lots of parasitic signals. 

Thanks again, I did not understand and opened my HL2, tried to remove the main board to check everything and clean the board but it is stuck by the thermal medium to the heat shim and the enclosure and I was wise enough to try to use powerful tools to unstick it!

Thanks again for your help and this wonderful HL2 you have designed, I was starting to despair but this group is of great value and help.

73 - Pierre - FK8IH

[Steve Haynal]

Hi Pierra,

I'm happy your problem is solved!

73,

Steve

kf7o