PGXL

Bill AB7AA

My PGXL drops off if transmitting into a 40 M antenna with 1.5:1 SWR or greater.  Same type of problem that it used to have on 80/160M before the latest firmware update 3.2.15 fixed it. Flex boasted that it would handle 3.0:1 so I thought that it would give me full 40 M antenna bandwidth but it is more limited than my Alpha 87A.  Can the same fix that was implemented to correct the problem on the lower bands also be used on 40M? 

I have yet to resurrect my 40-10M log periodic antenna that has varied SWR below 2.5:1 on all bands that I suspect might also exhibit the same problem when I get it back up.  Why not use the same fix on all of the bands?

Bill AB7AA

bahillen

Try turning off Meffa. I don’t understand what it is doing specifically, only on a general basis. When I turned up PGXL power SWR would go up above 300-400 watts. And would het a HISWR screen on the PGXL utility. I thought I has an antenna problem. I turned off Meffa in the tools as I recall and everything worked fine. No hi SWR and no strange behavior. I was using on WSJT and they indicate Meffa is for CW and SSB. Doing to many other things to investigate. Thought this may be helpful. 73 Bill W9JJB

Bill AB7AA

Thanks for the input but it did not help.  PGXL still kicks off.
Bill

Brian Morgan VK7RR

If you have a proper dummy load, check how things go into it, instead of an antenna. It sounds to me like you have had RF feedback in your system both with the Alpha and the PGXL.

NX6D Dave

The fix applied to all bands.  Please open a Help Desk ticket so the hardware guys can have a look and deal with the problem.

Bill AB7AA

Thanks Brian but both the Alpha and PGXL work fine on the same 40M antenna when tuned to the center of the bandwidth.  It exhibits the same behavior that it used to have on 80/160M antennas when getting out of the heart of their envelope but fixed with the latest firmware.  No doubt that there is some reactive component that presents the problem when tuned more to the edges.  Using a dummy load would not tell much, it needs a real antenna.  No doubt it was designed using dummy loads and it loves purely resistive antennas even if at other than 50 ohms.  It might just present a problem when there is a slightly reactive component value that would only show up with a real antenna.
Bill

NX6D Dave

The amp will trip off when it sees reflected power above a calibrated limit.  A limit is stored for each band.  To the extent that the reactive component of the antenna load causes reflected power, you are correct.  Any significant impedance mismatch in the antenna system at any given frequency will cause reflected power, as you know.

When the amp trips off, you should be seeing an error message on the front panel display.  Would you please note that message and post it here?  Also, please mention the output power at the time of the fault.

Bill AB7AA

Hi Dave,
  The PGXL is in another room and the message is gone by the time I get out there, but the software utility says "High SWR".  Power is about 1.2K but hard to capture because it faults so quickly.   It works sometimes at lower power (800W) but may kick off on peaks.

Bill

Jim K4JAF

Sure glad I did not purchase a PGXL when first offered....  

bahillen

Jim, you are missing an outstanding amplifier. There are new things that it does that are easily picked up. Changing bands and power is just where I set it in prior Q on that band. I worked in the digital contest and 50% duty cycle at 1.5 KW. Solid. It is a commercial quality amplifier. I couldn't be happier. Remote operation is a breeze with the amp.
73
Bill W9JJB

Brian Morgan VK7RR

Hi Bill,
My theory behind testing with a dummy load is to see whether the tripping is caused by a reactive component in your antenna feed or through simple RF feedback. The fact that it only happens on 40 metres points more to antenna issues, although as NX6D has pointed out the linear may be set for tripping earlier than you might expect. I like to eliminate possibilities, then the probabilities become more evident. Good luck with resolving your problem.

DH1RK

Hi Bill,
could it be arcing (isolation not okay)?
Did you check the SWR with a fast (digital) meter?

73
Rudy, DH1RK

[Deleted User]

My KPA-1500 just hums along and it has a tuner in it.

Clay N9IO

Bill I would open up a help desk ticket and have them help you sort this out. I don't think you're going to find your answer here.

Burch - K4QXX

Interesting thread.  My PGXL works great but for some reason it doesn't like 80 meters.  I can't run more than about 200-300 watts on 80 meters before the amp goes into "High SWR" mode.  I thought I might be getting RF into the radio/amp but I put up another 80 meter antenna (first antenna is StepIR vertical and 2nd is 80 half wave dipole) and the same thing happens on both antennas.  I did recently upgrade the firmware on the PGXL but I haven't tried 80 meters yet.  I will try tonight and see if the firmware fixes the issue.

Bill AB7AA

Thanks Burch Yes, my PGXL had the same issue on 80 M too until I installed FW 3.2.15 that fixed 160/80 but they didn't implement the same fix for the other bands.  Looks to me like they should have included at least 40 M with the fix and maybe all other bands too.

Bill

Bill -VA3WTB

The PGXL has been tested extensivly on 80 meters. I have talked to a few people on 80 meters and they do not have any problems. In your case it is hard to know what is causing your problems. I hope the Help Desk can help sort it out.

KL4QG

What is PGXL

Bill -VA3WTB

Joe, it is the Flex amp

KL4QG

Ok thanks

Asher - K0AU

Strange one, but in ARRL DXCW noticed my PGXL has low output on 40M. Antenna has 1.06 VSWR in the 40M CW band. Tried disabling Meffa and no change

Can get up to 600W on 40M. Other bands appear to have normal power, even though most have higher VSWR. Low power whether exciter is on Ant1 or Ant2.

bahillen

What happens on a dummy load. What is the exciter power to get 600 watts on 40 m. Try a test with measuring drive power to get 100-600 watts in 100 watt increments, it it linear input vs output. Check the various places that control max power. For testing set max power to 100 so the software is not confusing your analysis. Try a through line wattmeter between flex and PGXL. I would turn off Meffa during test to prevent confusing data. Different bands and load reactance can require different drive requirements. 1.06:1 doesn’t necessarily mean 50 ohm resistive and the PA may not necessarily be 50 ohm resistive. Check antenna with antenna analyzer and look at R+jX. Try putting a 10 foot extension to your antenna feedline. It will rotate the impedance around the Smith Chart and change what is presented to the PGXL. You may be surprised at the change in match between PGXL and antenna. Remember that a solid state amplifier has no tuning so it may be different in a way you wouldn’t expect. The above may have nothing to do with you problem but may help to analyze these kinds of problems. Let us know what you find as it can help others. I have seen some different behavior on various bands some requiring more drive than others an I set my max drive power to 50 watts. Rain and ice on the antenna changes my antenna SWR. 73 Bill W9JJB

Asher - K0AU

All excellent questions. No dummy load so I can't answer that question! I did try loading into my long wire on a remote tuner, and saw similar results on 40M. I was kind of hoping there's a secret software log on the PGXL utility that might show the problem.

on 7.050 with VSWR 1.06, measuring power with PGXL Utility AND with a PowerMaster. The PM is about 5 LMR400 feet from the PGXL output. The Antenna is an Optibeam OB2-40M fed through about 200 feet of LMR400. I'll put the RigExpert on it later to see if anything strange has happened.

Drive/PM/PGXL
5/115/125
10/260/284
15/441/445
20/566/573
25/600/611
30/613/625
35/618/630
40/623/633


On 28.050 with VSWR 1.26
Drive/PM/PGXL
5/380/400
10/150/164
15/600/630
20/j785/819
25/927/964
30/1048/1109
35/1159/1220
40/1253/1316
45/1349/1420

60 degrees and sunny today, so I also can't blame the weather

bahillen

In your first table, 20 watts produces 573 watts and 40 watts 633 or .4 dB. On 28 MHz 20 watts is 819 and 40 is 1316 or 2.1 db. With 3 dB drive The amp is cutting back on 40 m. If you can compare on a 50 dummy load it would be helpful to know. With the PGXL utility check the temperature to see if temperature rise is similar. Use 20 watts and 40 watts with the two different bands, 40 m and 10 m . This info would help with a help desk ticket. Did you try to add a 3 to 10 feet feedline length change. I just thought you could have a pl-259 connector problem. It would not surprise me to find an insulator in the antenna leaking over. I have had two fail in the past with similar confusing behavior. Lightning arrestors can also degrade but have no experience with this. I did choose 3 kv arrestors because of surprisingly high voltages that could be seen or a weather event. 73 Bill W9JJB

bahillen

Time to open a help desk request. They have experience with this behavior and can react quickly. Try to borrow a 50 ohm load. What release of software are you running? 3.1.8? If so have you tried 2.4.9? 73 Bill

Tim - W4TME

Asher, please open a HD ticket for this issue.  I suspect there is an issue with the 40m filter.

Asher - K0AU

Tim,

Will do. Thanks!

KF4HR

Bill, I'll be really curious to know what resolves your situation.  I've had no problems with my PG-XL, but have always operated it at low SWR (<1.25:1).  Since the PG-XL is one of only a couple of HF Amplifiers on the market that offers dual through-put connections, I use two HF-AUTO ATU's, one for each port of the PG-XL.  

bahillen

Ralph, When I had problems, the insulators developed a leakage path across the insulator. SWR was low during tuning as power increased the leakage increased and SWR would go up. And amp would cut back. Eventually the insulator shorted with some flame. This has happened twice on wire antennas. I have been changing insulators to ceramic or glass. My belief is that operating in snow and ice started the problem. Asher’s problem is probably different as Tim made a comment that the 40 filter is his suspect. I am anxious to hear what solves his issue. 73 Bill W9JJB

KF4HR

Thanks for the reply Bill.  It sounds like your PG-XL was doing what it needed to do to protect itself.  I suspect the SWR peaks may have been higher than what was being indicating, perhaps due to Ethernet communication latency.

Did the problem disappear when your PG-XL was fed into a dummy load?

Brian Morgan VK7RR

I have no idea of your setup but this thread prompted me to add a problem I experienced with my station some years back. It started with similar problems, reduced power out on one or more bands, VSWR on tune, was excellent, using my Bird Wattmeter, power out was not reduced into my dummy load but on my SteppIR I continued to have reduced power out on some bands. The problem was that the lightning arrestor which was in the heliax to the SteppIR was defective. Rather than being an open circuit, from a close lightning hit, it would become intermittent when I used full power. I replaced it as I couldn't think of anything else that could be causing the problem, It has never occurred again. I was able to replicate the problem in my workshop using the same lightning arrestor and a dummy load.