PGXL sudden power drops and HIGH SWR errors

Frank ON9CC · March 30

Hi all,

We're having issues with our PGXL. This weekend extensively noticed during the CQ WPX SSB contest. Normal operation is Power out is about 1500 Watts or so. Then it often happens that the power is reduced to only ~300 Watts when starting to CQ, then during the CQ call, it shoots up to 1500 Watt again. Next CQ is normal. Then it can happen that suddenly during the CQ it drops from 1500 Watt to 300 W. This is as we speak happening on 10m. SWR is about 1,3:1 to 1,4:1, also when the issue occurs!

Since we've been seeing this before, so this morning I used a Bird 8251N dummy (1kw continuous) and tested with a short coax directly connected to the output of the PGXL (to exclude any issues with the antennas or 2 AG's and A/B swithces, power meter sensors, coaxes, antennes etc.) and I could reprocude this concern. SWR on the dummy was ~1,2:1 or so. I have captured this behaviour this morning in a video with my phone this morning (if needed I can sent).

Besides this, we've noticed that if the SWR on the antennes is just slightly above 1,5:1, intermittently we have a HIGH SWR message and the PGXL totally blocks TX.

I've checked the manual and it states the PGXL should only show this when the SWR gets up to 3,0:1 … but none of my antennas is that bad.

We've seen this behavour in both SSB and CW, on several bands, on several antennas. But as stated, most important, we've been able to reproduce it on a high power high quality Bird dummy load with a low SWR. Is there a possibility there is something wrong with the way the PGXL measures the SWR (realising that it measures very very fast, as mentioned by Mike), or any other internal issue?

Some further information:

driving the PGXL with a Flex 6600.
behind the PGXL we have 2x Antenna Genius, coupled via 2 A/B switches so we have 16 antenna ports in total. We're aware of the higher/lower bands distribution on the AG's antenna ports.
measuring the power additionally with a WX0B Power Master II with 2 sensors, 1 in each coax from the PGXL.

We've bought this PGXL new from Wimo in Germany and it's still under warranty… anything that can be checked via remote? Or do I need to contact Wimo for sending it back for repair? Thanks in advance!

73 Frank ON9CC / OT6M

bahillen · March 30

Frank,

I would request help desk support. From past conversations with help desk that indicated half the power supply is shutting down. Observe the VDD voltage on the amplifier. It is probably in the design to protect the LDMOSS. It may be in the timing or even a relay sticking which I have had. Try increasing the TX delay setting. Mine is 60 ms.

Do you have a Tuner Genius in the setup. That maybe a factor.

73

Bill

W9JJB

Erik Carling EI4KF · April 3

Frank,

I would be grateful if you would post here what action / remedy you have taken to solve your issue.

My PGXL is also quite new, having been bought from WiMo at the end of last year (in their Black Friday sale). Until 4 days ago there was not any problem but now something similar to your issue has started occurring.

On starting a transmission on any mode, the power is a few hundred watts less than it should be and then shoots up to what is expected. For example, testing a constant carrier mode into a dummy load (I chose FT8 and then CW), setting the power to 1100 watts out exhibits a starting output of circa 800 watts and then it will go to 1100.

My VDD voltage remains stable. I have tried increasing the TX delay.

I am currently in hospital from today until who knows when. I should have done something in the last 4 days but with my health issues I forgot. Now I have very limited access to internet / email and would really like to know any definitive answer as to who to contact and then my XYL can arrange shipping if indeed that is what will be required.

Thanks,

Erik.

Frank ON9CC · April 5

Update on this issue: I've submitted a ticket to Flexradio and they stated that I've carried out all possible tests and they suspect an issue with the LDMOS transistors. They advised me to contact Wimo in Germany where I bought the PGXL. So I contacted Wimo and they asked me to ship it back to them for repair, which I will do in the next day or 2. I'll keep you posted.

@bahillen : we've already increased the delay but even then the issue keeps appearing.

73 Frank ON9CC / OT6M

Erik Carling EI4KF · April 5

Frank - hello, thank you for your update. My PGXL has same fault. Tim Ellison at Flex also advised me to contact WiMo but I sent WiMo email only yesterday so have yet to hear from them. Presumably I will also be sending it to them for repair in next days.

73 de Erik

PGXL sudden power drops and HIGH SWR errors

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