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PGXL power meter reading
The power meter on the PGXL always shows 2-300 watts higher than ANY power meter I put in line. I have tried the Array Solution Power Master II (new), LP-100A, CN-901H, Bird with peak reading capabilities...WHY? It is the same results no matter the antenna/dummy load
Comments
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Hi John,
I can confirm your power reading discrepancy with a TGXL, which is supposed to be the more accurate of the two. It may even be 400 watts difference at times.
So then comes my dilemma. Do I believe the TGXL and operate 1500 watts peak with the PGXL meter reading 1800-1900 watts and possibly illegal? Or, do I conservatively set the PGXL to 1500 watts peak and reside that I only bought a 1200 watt amplifier?
73,
Bill AB7AA
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I think you need to pick which one you feel is the most accurate and live by it.
In the 1970's when I was licensed, the FCC used to have monitoring vans that drove around and once they were in in my neighborhood. I was just a teen but asked what they were checking for and they said there had been a report of a very wide and dirty signal and they were trying to track it down. No it wasn't me! I had a general and 100w to a vertical. I spent 90% of my time on CW and they were looking for some voice signal.
I think these days are long gone. I doubt the FCC has the budget and/or the time to do these kinds of things anymore. So whether you TX 1400 or 1600 watts, I don't think the FCC is going to storm in and cite you.
I think rather like my example, if you are regularly running over limit and causing interference, then you could run into a problem at some point.
I also feel this is a little like 30m operation. My PGXL setup can output 1500 watts or more on 30m but we are limited to 200. The best I can do without investing in a very accurate watt meter is adjust my drive so the PGXL is putting out 200. I might be at 140 or I might be at 230. I don't think it really matters if I'm not interfering and I'm operating with best intent.
This is just my 2c. I'm not a lawyer.
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John
i have TGXL and PGXL and they read within 50 watts. I am not sure what the difference in location of the TGXL meter in the circuit and have been curious myself.
I would think the use of a dummy load would be important in your evaluations. The latest firmware has been an improvement in power measurements.
man interesting thing I have done with matching and tuners it to add 2 or 4 feet of coax on line to antenna and see if matching changes.
I would open a help desk ticket to get some resolution.
73
Bill W9JJB
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Bill,
I did as you suggested and connected to a dummy load with the same results as the TGXL, about a 400 watt difference.
I don't like Mark's comment to just choose which one you think is more accurate. Not just because of the legality issues, but the PGXL at 1750 watts starts to warn of APC, before the TGXL has reached 1400 watts.
You would think as universal as this problem could be that Flex would provide a solution.
Bill AB7AA
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Well...some good comments so far, BUT...when investing this kind of money on the LATEST and supposedly the greatest, I DO EXPECT for it to be accurate. No, I do not agree to "choose one", I want the PGXL and when the TGXL gets here to be the same and to be accurate...WHY is that so much to ask for. I would certainly understand if I were to have purchased an MFJ product, but, those of use that own these spent the $$ to have the best...NOT to settle!!
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This is not normal operation!
help desk. This issue can’t be fixed on the blog.
just had a idea of standby the PGXL and compare power from exciter with TGXL. (turn off exciter tuner) 50 ohm load.
73
Bill W9JJB
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I agree it cannot be "fixed" here...wanted to see if there were any others with the issue...ticket has been generated for two days...Tim has forwarded it and am waiting for response. You cannot use the metering in the PGXL when in standby...
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Olde school .. but still relevant. You want to know how much power the amplifier is supplying. You can't rely, or shouldn't rely on metering within the amplifier or tuner. Best solution is to get a calibrated wattmeter, I use Bird wattmeters, and measure output into 50 ohms. At that point you should be rather confident that you are legal.
One interesting point that I have pondered is the trend toward 2000+ watt amplifiers and ancillary equipment. Really? Headroom? No .. I suspect that if you can run 2000 watts there are many hams that will run 2000 watts. Manufacturers know this .. and my cynical view is that there might be very few 200 watt signals on 30-meters with stations running amplifiers.
Last point in defense of my cynical nature. When I was looking to buy a sailboat to sail around the world, I would survey many sailboats that had ham transceivers. Of course, I had to ask about their ham callsign and their ham career. 80% of the boat owners stated that they never had a ham license, saw no need to get one, and that they, in general, just tried to find a deceased ham or pulled a callsign out of the air and took their chances. That didn't always work though, as one sailor said a ham contacted him that reported he was using his best friend's callsign, and that his best friend had passed away years before.
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W7NGA makes some good points but I've found most hams do follow the rules and are concerned about keeping their power level legal. But many also prefer not to own an amp that is designed with components that get pushed to their absolute limit, to reach legal limit power.
It's nice to have a fairly accurate wattmeter on the amp, but I'd never rely on it for accurate readings. I use an external power measuring device, either a Bird 43 or LP-700.
KF4HR
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I agree on most comments, but AGAIN...my point is that the metering in a $7k amplifier should be accurate whether running 300 watts or 1500 watts. As mentioned, I have all of the best external meters, but this was one of the things that attracted me to purchase the PGXL and it is NOT accurate on "mine"...so far...after Flex contacts me, maybe it will be a different story...
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I agree John ... that is a very large discrepancy and a clear indication of something not quite correct.
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Got my TGLX in on Tuesday, wow, lovin it, hear are with PGXL at 1000w then near legal limit 1479.
With the PGXL at 1000w the LP-700 read 912w, where the TGXL read 916w. I get same results using either ANT 1 or ANT 2 with same antenna and tuning solution as was expected.
With the PGXL at 1479w the LP-700 read 1398w where the TGXL read 1393w.
NOTE: The LPC couplers are on the outputs of the PGXL.
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Thanks for posting this Mike. That's not too bad! Just curious, have you noticed any additional accuracy into a dummy load?
Butch, KF4HR
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Has anyone gotten a formal response on this issue from Flex? My power readings on 3 separate power meters that read peak and average are ALWAYS. 200-300 watts lower than indicated on the PowerGeniusXL. Into dummy loads, etc.0
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Assuming the wattmeters are totally accurate (they aren't), going from 1479 watts to 1393 watts is about 1/4 of a dB. That is really small.
There is a connector on the PGXL, a length of coax to the TGXL, and a connector on the TGXL. The total loss would be .26 dB for all three. That excludes the losses inside the units to get from the wattmeters and the connectors.
K1ESE
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A few things here.
It is not uncommon to see different RF readings from different devices on the same feedline. This is normal. I know that sounds strange and for years, we only have 1 watt meter in line.
The ARRL explains it here:
To test this accurately, you want to do a bench test with each device, 1 at a time into a 50 ohm resistive load. If you don't own a 2000 watt dummy load, they aren't expensive and highly recommended. After all, you have this much invested in your station already.
That is how they are calibrated in manufacturing on a constant carrier transmission.
In Mike's photos, you can see the SWR is almost 1.0:1, but it isn't and this can contribute to variances.
Measuring SSB or PEP power is much more difficult and to do it correctly requires a lot of RF sampling to correctly measure the envelope power. Dave, who does our PGXL firmware, has spent a lot of time working on the PEP measurements and comparing them to a bench standard. It isn't as simple as it seems and that is why an LP-700 is so expensive. To see a 5-6% difference in PEP measurements is to be expected. The PGXL is not a bench standard.
The work continues. 73
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Interesting, measuring power and SWR along a transmission line with different meters/components will always give some differences, of course the perfect results would be something giving the logic picture.
I have a 6600 with tuner option which will be disabled, and also have a LP-700 with 2 probes, when I receive my PGXL TGXL and AG8x2 installed on my remote location, my aim is the following order;
6600-probe1-PGXL-TGXL-probe2-AG8x2. Or should I put probe2 before the TGXL ?
Coax cable lengths between will be as short as convenient.
I have a win-11 pc on remote location which I use to run the utility programs, and which I use via TW to run Slice-master, Frstack, WSJT-X and Gridtracker etc.
I also have Node-red on Raspi running only relays for the moment, PTT and power, and my existing antenna switch and would like to control the PGXL TGXL AG8x2 and readings from the LP-700, all by the guides and examples provided in the node-red forum.
It will be very exiting to see my results on power and swr for sure.
I’ve been using Smart SDR on IPad Pro 12.9, and yet holding back on getting the Maestro.0 -
I tested my PG XL using a Monitor Sensors digital meter. https://monitorsensors.com/ham/swronly/
Mostly both agree to within 3%. There are some discrepancies on 40m. With 60w drive as indicated by 6600, the output power in CW is 1280 W by the meter and 1320 by PGXL. Very close. In SSB with AAB, the meter shows 1480 and PGXL shows 1780.
So far, my measurements show that about 60W is required for legal limit in SSB, and 70W in CW.
Always I wonder which meter is OK. The digital meter agreed with a Daiwa analog meter. When I bough LP100 years ago, its readings were weird. Turned out is had a calibration error. So I am not taking anything for granted.
It seems that PG XL readings are inflated in some cases in SSB.
Ignacy NO9E
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Someone with a watch knows what time it is. Someone with two watches is never really sure.
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This is a well-discussed area, especially when it comes to SSB.
It does take time and equipment to correctly calculate the power in an SSB Envelope. The LP series of Watt meters by Telepost Inc do it very well and they are the standard we use when calibrating the wattmeter. They are calibrated devices.
In the PGXL there just isn't the computing power to do all the math all the time to get it 100% right, so there are some averages that are used.
In expensive watt, meters use a very simple method to capture the peak voltage and then 'hold' it until it decays.
Both the TGXL and PGXL will give you numbers that are close enough.
If you want to know your peak Wattage accurately, I would recommend investing in an LP100A, LP-500 or an LP-700. All are excellent.
I use the LP-100A on my remote station with dual probes and thanks to NodeRed I can read the data on any web device, including my cell phone.
This is one of the cool features:
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"In SSB with AAB, the meter shows 1480 and PGXL shows 1780"
...
It does take time and equipment to correctly calculate the power in an SSB Envelope.
The original measurements were done in tune mode so no peaks.
Ignacy NO9E
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In your test, was this into a dummy load with a 1:1 SWR. This is important as reflected power will affect the power readings.
If not, the power readings will vary along the point of the feedline. Check out the QST article I posted above for why this happens.
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PGXL resolution on the display of Power is not as accurate as TGXL. If both meters agree it is almost an accident. Use the TGXL power indicator as ballpark, the TGXL is the more accurate of the two.,
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Ignacy,
I have been asking this very same question for several years now and get the same run-around answer. However, I get more of a discrepancy in power levels-1370 on the TGXL and 1903 on the PGXL into a 50 ohm load and nearly 1:1 SWR. This while trying to hold the same consistent voice audio level while simultaneously reading the two power levels. The TGXL continuously reads much lower than the PGXL in SSB but nearly identical in Tune. I tried pointing this out to the Flex technician when it was recently back at the factory but he obviously didn't understand the problem as he sent a calibration video of my amp only in constant tone Tune.
So, if I believe the TGXL meter and drive the amp to 1500 watts based on it, the TGXL goes into overdrive mode and either lowers drive level or cuts out altogether. To preclude hurting the amp, I lower the drive mode so that the PGXL peaks at 1500 and not to trigger any alarms. However with this low of drive the TGXL peaks at just over 1000.
So…did we spend our money for a poorly designed PGXL power sensing system that artificially limits the output or did we only get a 1000 watt amp. Either way, my SPE 2K-FA does not have this, nor any other problem.
Others: If you have a dummy load and understand the problem, try your own test and list the results here.
73,
Bill
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Bill,
Yes, it is absolutely possible to get different power readings between the TGXL and PGXL, especially on SSB, and what you’re seeing is not as mysterious as it first appears.
First, it’s important to understand that RF power can only be measured accurately into a true 50 Ω resistive load. A 1:1 SWR does not guarantee that condition, since there can still be reactance present. Depending on how each device samples voltage and current, that reactance can introduce differences in calculated power even though SWR looks perfect.
The bigger factor here, though, is how each unit measures power, particularly on SSB. In Tune mode, you’re dealing with a steady carrier, so nearly any metering system will agree because the signal is constant. That’s why your TGXL and PGXL line up under those conditions.
SSB is a completely different animal. Now you’re dealing with peak envelope power, and that depends heavily on the sampling rate, detector type, and averaging algorithm used in the meter. If one device has faster sampling and better peak capture, it will report higher PEP. If another effectively averages or undersamples the waveform, it will read lower. That alone can easily explain a spread like 1300 W versus 1900 W on voice peaks.
So what you’re likely seeing is not a “bad” power sensor, but two different measurement implementations. The PGXL appears to be capturing peaks more aggressively, while the TGXL is reading more conservatively. Dave NX6D (SK) who wrote the algorithms for the PGXL spent months working on the peak algorithms and consulted to many other engineers and often used an LP-100 and LP-500 for reference. The PGXL also has more processing power than the TGXL so it is able to sample the RF on much higher rate.
Your observation that driving the amp based on the TGXL leads to PGXL overdrive protection actually supports this. The amplifier is reacting to the higher true peaks, even if the TGXL isn’t fully reflecting them.
Bottom line: this comes down to measurement methodology, not necessarily a defective design. But it does create a usability problem, because the operator is left trying to reconcile two different definitions of “power.”
73,
0
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