Blown PA?

[Joe Fratzel]

Hello all,

New to the Hermes Lite. I have latest build version 9. I think I might have blown the finals. When I use the spot, current go to @2 amps but the output is only .6 watts. I also notice the temperature rising. I can confirm on wattmeter. Doubled checked all the settings in quisk. Any suggestions?

Thanks

[st...@radio-kits.co.uk]

Hi,

Check the filter is set correctly....

Steve G6ALU

My CLT-L09. On O2.

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[Steve Haynal]

Hi JFratzel,

The filter settings are definitely something to check. You could see such behavior if transmitting on 20M with the filters set for 80M. Can you post a screenshot of your filter settings?

Check that there is a solid connection between the HL2 and N2ADR board. Maybe turn the header 180 degrees to see if that makes a difference.

In Quisk, power is limited per band on a separate tab. Go to that tab and make sure the power allowed on every band is set to 255.

Are you connecting to ANT or RF1? Make sure you are connected to ANT, and that the PA is enabled in Quisk.

Where are your current measurements coming from, HL2 or direct measurements of the DC power in? 2A is a bit high if your current is what is reported by Quisk. Do you still see 2A if the spot level is set to 0? Do you still see 2A if you turn the PA off? (You can TX without anything connected to RF1 in low power mode without concern.)

73,

Steve

kf7o

[Joe Fratzel]

Hi Steve,

Here is the quisk setup for the filters. I turned the filter header around 180 degrees but it made no difference. When I originally started testing the board, I could have sworn the output was at 4.5 watts. But after I installed the spacer, I can only get .6 watts. I tried without spacer but it is still .6 watt and the temp rises really fast. I have the PA enabled and the antenna is attached to the ANT connector.

If the spot level is set to 0, I get 200 ma. and with the PA turned off I get 0 ma. Anything else you can think of?

Thanks,

Joe WA1KLD

[Steve Haynal]

Hi Joe,

The filter settings look good. Please check that J31 and J32 are still present on your board, and measure 0 Ohms. There is a picture on this wiki page, third one down under the Heat Shim heading and includes yellow arrows pointing to J31 and J32.

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

73,

Steve

kf7o

[Joe Fratzel]

Hi Steve,

Finally got to check the 2 jumpers. Both are there and are at 0 ohms. Anything else I can check?

Joe WA1KLD

[Kristofer Danner]

Joe, do you happen to have a conductive washer between the nut and the HL2 board? Something I ran into once, the washer OD was a little too large and it was shorting to one of the traces between the 2 MOSFETs. In my case it didn't damage anything, just was way down on power until I removed it. Maybe worth pulling the boards out of the enclosure and then doing a quick test to rule out any of the enclosure hardware causing the issue.

KD

[Joe Fratzel]

Hi all,

I do not have a washer. I get the same high current with the board out of the case. I do have the spacer mounted. I had to file it some to get it to fit and I did use thermal paste. I will try to clean the circuit board later today in case some of the thermal paste got on any components.

Thanks,

Joe WA1KLD

[ron.ni...@gmail.com]

If you had to file the heat spreader to get it to fit, you may have damaged or dislodged some surface mount components on the back of the PCB.  So you might carefully inspect that area.  And carefully re-read how to install the heat spreader (several people seem to tried installing it backwards or upside-down).

73,

Ron

n6ywu

[keyboa...@gmail.com]

Hi, Joe. Just reading along here and thought I'd throw in my experience. 

When I installed my heat sink shim (third time actually) I managed to break off B106 on the top side of the board using needle nose pliers to tighten the nut. It's quite close and easy to do.
You might check that as well. Your symptoms sound about the same. Steve sent me a replacement. Re-soldered and good as new.

Now to avoid touching the shim again...

73,

Jayson

AA7NM

On Sunday, January 24, 2021 at 7:27:35 AM UTC-8 jfra...@gmail.com wrote:

[Joe Fratzel]

Hi Jayson,

Thanks for the reply. It looks like it's there but I will bring it to work tomorrow. They have a nice illuminated magnifying glass I can use to look at the board. I did have a lot of trouble getting the shim to fit and the first screw and nut were too big.

Regards,

Joe WA1KLD

[Joe Fratzel]

Hi all,

I used my phone to zoom in. It looks like B106 is missing. Would this cause the high current and low wattage? Where can I find the BOM so I can get the part number?

Thanks for the help.

Joe WA1KLD

[Steve Haynal]

Hi Joe,

Yes, a missing B106 could cause these problems. You can find the schematic and BOM for the build9 release here:

https://github.com/softerhardware/Hermes-Lite2/tree/master/hardware/hl/releases/hl2p0build9

B106 is a 0.1uF 0605 capacitor. It does not have to be the exact part number listed in the BOM, but should be X5R or X7R and rated for 25V or higher.

Are you comfortable making the repair yourself? If so, do you have a suitable capacitor? If not, let me know and I can send a few capacitors in the mail.

If you are not comfortable making the repair, you can send just the HL2 card to me using a ~$8.00 priority prepaid small flat rate box. I will make the repair and reimburse shipping out of the repair funds. My address on www.qrz.com is correct.

73,

Steve

kf7o

[Joe Fratzel]

Thanks Steve,

Send me the part and I can solder it. If that doesn't work, I will send the card to you. My address is correct on qrz. Thanks to everyone for their help.

Joe WA1KLD

[Joe Fratzel]

Hi Steve,

Can you please send me a couple of the capacitors and I will solder it in. My address is 119 Stevenson Road, Meriden, CT 06451. I appreciate your help.

Joe WA1KLD

[Steve Haynal]

Hi Joe,

Yes, I sent 5 via regular mail today, in a padded envelope.

73,

Steve

kf7o

[Joe Fratzel]

Thanks Steve, I will let you know how I make out.

Joe WA1KLD

[Steve Netting]

Hi All,

At risk of reducing the SNR ratio, I just wanted to add - I've been running the HL2 24/7 on automated modes at full power output with just the standard enclosure and rear fan (running at constant low speed).

I assembled this before the shim was available and at least from here, the shim seems to cause more problems than it solves.  I barely see a temperature change even when dumping full power into less-than-ideal loads.

Steve 
OH3SPN / M0SPN

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[Joe Fratzel]

Hi Steve,

I looked at your website and your enclosure is twice the size. I did see some examples where there is a place for a fan on the back plate. Unfortunately, the enclosures are only 40 MM tall so there is no room for a fan. The only way to add a fan would be to mount one on top or buy a new enclosure.

BTW - did you ever decide to get an amplifier"

Joe WA1KLD

[Steve Haynal]

Hi Joe,

Yes, there is an option for a 55mm high enclosure. Unless you are in the Outback, I don't think a fan is necessary or very helpful. Some people like to put rubber feet on their HL2 and then cool the entire unit with a small external fan. I think people see a rise in temperature and worry. There is no need to worry unless you start hitting 50C to 55C. The unit will shut off TX at 55C.

I am a true QRP guy and not very interested in an amplifier. I am interested in synchronizing two HL2s into two antennas. 

73,

Steve

kf7o

[philwill93]

Hi Steve,

I also damaged B106 during assembly of the heat sink. Could you repair it for me? I'm too old and shaky any more!!

If so please reach out to me. 

Thank you,

Phil

K4PAW