OK that explains why testing my GDT with my Zapper sometimes works and sometimes it does not. I just repeated the Zapper test one more time on the other unit where the GDT seemed to have failed to protect the circuit and guess what this time the unit did not encounter a latch-up anymore, even trying multiple times.... I find it is important to install a GDT as well as an external Lightning surge protector like this one from Alpha Delta Of course, these are available from many other manufacturers like MFJ, Diamond, Polyphaser etc.

Alternatively, if you power the Transmitter from a Raspberry Pi USB Port adding this command to the crontab of user root will restart the USB port in the event of a latch-up 0,20,40 * * * * ( /usr/bin/test -e /dev/ttyUSB0 || /usr/sbin/uhubctl -a cycle -p all -l 1-1 ) This requires the prior install of the uhubctl utility sudo apt-get install libusb-1.0-0-dev git clone https://github.com/mvp/uhubctl cd uhubctl make sudo make install

I received a batch from this store today https://www.aliexpress.com/item/1005001779980367.html?spm=a2g0o.placeorder.0.0.612d321etEd8fu&mp=1 They arrived within 10 days, very quick. Cheap Logilink clones but all 5 I ordered are working just fine.

For those of you running into the Latch-up issue with the Beacon Hardware, I have found a reliable workaround using one of these USB Power Meters. These inexpensive USB dongles allow monitoring of the current draw of an attached USB device. In a latch-up event, the current drawn will exceed 1A (spike). The USB dongle can be configured to shut down the USB Port if the current draw >500mA. After a few seconds, the USB Port will be enabled again resulting in a reboot of the WSPR Transmitter. I have tested it with my Zapper and it works consistently. https://www.icstation.com/tester-current-voltage-capacity-power-test-mobile-phone-charger-mobile-power-bank-safety-monitor-p-15836.html Roland

New Observation. When I power the Transmitter from a USB Port of a Raspberry Pi 3B+/4 I can no longer get the TX Hardware to fail with the zapper (it just reboots) while powering it from a 5V USB PSU or from a Notebook USB Port it goes down every time the Antenna socket is being zapped. This is consistently reproducible on my side. Can somebody confirm? P.S: That is all without an installed GDT! Could it be that during the latch-up event the current draw spikes above 1.2 A for a short period of time? The RPi 3B+/4 provides a Max. of 1.2 A through its USB Ports. My theory: If the current draw exceeds 1.2 A (Polyfuse) the RPi will reset the USB Ports and therefore the Transmitter reboots. Edit: When powering the Transmitter from the RPi USB Port and zapping the Antenna connector I do see an over-current message (dmesg): usb 1-1-port4: over-current change #58 Roland

Really weird but there is no way I can reproduce the cure with the GDT anymore. Has anyone done the mod and tested it ? Roland

I have started experimenting with an external DYI surge protection based on the EPCOS 90V GDT B88069X4880S102 The UHF Plug connects to a T-Connector. The Banana Plug to ground. Currently waiting for the T-connector

I am having a hard time getting consistent results with my and Harry's provided GDT's. While I had no problems fixing the issue on my previous 3 Transmitters I can no longer get it to work on the 2 remaining ones (brand new) using the same zapper and the same GDT's. That's the one from EPCOS I am using B88069X 4880S102

That is pretty good evidence that after the install of your GDT the problem has been solved. Without the GDT your Beacon went down several times in the past and needed a manual reboot. Pls correct me if I am wrong.

Just installed another GDT on a second Transmitter (80to10) and the problem is gone. Just to verify the remedy on my side. I have tested with these 2 GDT's, both fixed the problem. https://www.distrelec.ch/en/surge-arrester-90-epcos-b88069x5010c102/p/16041198 https://www.distrelec.ch/en/surge-arrester-90-epcos-b88069x4880s102/p/16041024 73

I see you installed 2 of the GDT while I only installed one exactly like in the pictures in first Post in this Thread.

Just two quick videos showing the before and after results

After installing the GDT on my Beacon I can no longer reproduce the problem. Waiting for confirmation from Harry. 73 Roland

I can replicate the problem and just ordered a surge arrester https://www.distrelec.ch/en/surge-arrester-90-epcos-b88069x5010c102/p/16041198 Will test and report back 73 Roland

Just for the records I can reproduce the behavior with a lighter spark

VK4BA has no downtime for more than 3 months

Thank you Harry, good job and an important step forward. Keep it up 73 Roland

Thank you for the update Harry. Looking forward for your findings

Hi Harry, any new insights? I have stopped global deployment of the WSPR Transmitters until we have a clear understanding what the root cause is. 73 Roland

Thank you Harry, your Support is much appreciated! If there is anything you want us to try or need more Info let me know. 73 Roland