My 6700 power output is less than expected

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  • Question
  • Updated 5 years ago
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My 6700 puts out more than 70 or 80 watts max into a 50 ohm dummy load on any band according to the power bar indicator (SWR is 1:1). I read that some were seeing the full 100 watts. Is there a problem here with my particular radio, or is this a situation that exists on all 6700's?
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W5UN_Dave

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Posted 6 years ago

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Dudley - WA5QPZ

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Dave,

Be sure to check you power supply connections, that they are tight and not loose, grab and wiggle them, all the way to the radio. Just a slightly loose connection can cause trouble. Then check the voltage at the radio if you can under load, in TUNe , and drag the Drive to 100.

If it is still low output, maybe just a re-calibration of the PA will take care of it.. Then put a not into http://helpdesk.flexradio.com we can re-calibrate it .
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Steve - N5AC, VP Engineering / CTO

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What band, Dave? I'd like to look up the factory calibration for your radio and see how it did in factory testing.

Steve
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K1UO - Larry

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Is there a Utility Program available to run the PA power calibration routine here locally? My Elecraft K3 has such a Utility Program for the PA calibration at low and high power.....+ other things.
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W5UN_Dave

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Steve, I did not measure the exact power on all bands, but 6 meters seems to give the most output: 90 watts. Other bands varied vetween 70 and 80 watts. I hooked up a stand-alone 12.6 volt power supply (stable under full load) and used the power cable supplied by Flex with the 6700 to make sure this was not the problem. The load was a 50 ohm dummy load with a measured 1:1 SWR.
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Graham - KE9H, Employee

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Official Response
Dave:

To get the rated power output, you need to have 13.8 Volts at the rear connector on the back of the radio. If you use our supplied power cable, there will be less than a 0.1 Volt drop in the power cable.

73's
--- Graham / KE9H

==
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Robert -- N5IKD, Elmer

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Is there a place in SmartSDR (or the front panel) where we can read the volts that the radio sees?
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Graham - KE9H, Employee

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Not today, but that is a great suggestion. I'll enter that into the software planning system.
--- Graham / KE9H
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Ken - NM9P

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Yes, that would be great. Current drain, too, if possible.
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Don - kx9q

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I thought I responded to a similar situation. I am also experiencing 80 watts max on all the HF bands into a dummy load. I will check the voltage and I am using the Flex supplied power cable.
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Ed, K0KC

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I checked my 6700 with a Bird power meter into a 50 ohm dummy load (VSWR not perfect 1:1, but very close). I measured the input voltage as 13.75 volts at the power supply with 100% transmit power (can anyone suggest a simple way to measure the voltage right at the rig with the PowerPole connectors). I am using the Flex cable, so based upon Graham's comments above, I should have about 13.65 volts at the rig (all connections seem tight).

I measure from 70 watts out to about 95 watts out, depending upon the band.

What is involved in a re-calibration of the PA? Does it just calibrate the internal power meter or will it actually cause increased power output if that is appropriate?
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Tim - W4TME, Customer Experience Manager

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Ed, please submit a HelpDesk ticket on this issue.
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Ed, K0KC

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Done!
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Don - kx9q

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Ed, please let me know the results of your helpdesk ticket as I am also experiencing the same issue.
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Ed, K0KC

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Don,

Dudley indicated that I would need to send the rig in for re-calibration but he advised me to wait until v 1.0 is released just in case something else needs calibration. It looks like I will be doing a lot of testing in the next week or so
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K1UO - Larry

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Ed . you can purchase one of the small Y adapters from power worx e/w power pole connectors to more easily check the load voltage at the back of the rig. Think they have current testers also.
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Ed, K0KC

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Thanks for the idea, Larry! I will try this before I send the rig in. I wonder what the voltage drop is for the power pole connectors themselves exclusive of the power cable?
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Al / NN4ZZ

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Ed,
Here is another way to measure the voltage at a powerpole. It is cheap, works fine and easy to make. You probably have what you need;
- alligator jumpers
- safety pins (or straight pins, sewing needle, etc)

I have a few of these on the bench made from safety pins (snip off about 1 inch of the pin). The pin fits in the power pole nicely and they work for other hard to reach places as well.

Regards, Al / NN4ZZ

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Ed, K0KC

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Thanks, Al...I like cheap!
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Paul RN3A

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Just want to add my 2 cents here...

I am currently on v0.17.11 ALPHA. One thing I have noticed, that according to Power meter, the output power is below 100W on all bands, even when the slider is in the right most position. So I have performed some tests. Here is what I've got.

1. First of all, I have measured the Power Supply unit I was using, and discovered that the output voltage is 12,7VDC under full load. The output power of 6700 was appx. 80 Watts +/- 3Watts on all bands.

2. After increasing PS voltage to 13,8 VDC, the output power has increased to appx. 90 Watts, +/- 4Watts on different bands.

5. I have continued to gradually increase PS voltage, and after it reached 14,5 VDC I have started to get 100W output on higher bands (30 and up), and a little less on the lower bands. I have also noticed some variations of power output across Ham bands, especially 80 and 40 meters. Here is a small table with measured results.

160m 1,820 MHz 94W
160m 1,940 MHz 96W
80m 3,510 MHz 97W
80m 3,600 MHz 93W
80m 3,800 MHz 87W
40m 7,010 MHz 98W
40m 7,100 MHz 95W
40m 7,150 MHz 92W
40m 7,199 MHz 88W
30m 10,120 MHz 101W
20m 14,010 MHz 100W
20m 14,100 MHz 102W
20m 14,200 MHz 98W
20m 14,350 MHz 97W
17m 18,100 MHz 99W
15m 21,010 MHz 101W
15m 21,200 MHz 100W
15m 21,400 MHz 99W
12m 24,900 MHz 99W
10m 28,101 MHz 98W
10m 28,200 MHz 99W
10m 28,700 MHz 100W
10m 29,200 MHz 97W
10m 29,700 MHz 96W

All measurements were taken by LP-100A Digital Vector Wattmeter (Lab tested and verified), Telewave TWL-150 dry load and Fluke 289 Digital multimeter. Voltage measurements were taken on the output leads of PS unit. With the current drain of appx. 20 Amps, you can easily loose half a volt on the Power cables. This is normal.

I would say that irregularity of frequency response function of the PA and output filters is less than 0,4 dB in the worst case scenario, and this is acceptable result. As you can see from the table, the worst result was on 80m band, which is not really unexpected.

And I will just add, that results measured from other radios were not nearly as good. I will not be mentioning any names here, obviously.

Good job, Flex Radio!
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WA6FXT Mike

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Paul,

14.5vdc is getting pretty high. My PS wants to Over-Voltage Trip around that high. I'm running mine at 13.75vdc, measured at the F6700 connector and still anywhere between 75 and 90 watts, depending on band.

FRS, what is the highest SAFE input voltage we should apply? (Including peaks)

Mike

PS: Not getting response from the HelpDesk on this either. :(
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Steve - N5AC, VP Engineering / CTO

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The radio will shut itself off above 16V as I recall. The radio is calibrated at 13.8V, but it is fine to run it at a higher voltage. For all but the PA, the radio will consume a fairly constant level of power in W. The PA will make more power at higher voltages. You don't want to get real close to 16V since a transient from an unkey could shut off the radio.
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Al / NN4ZZ

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I suspect questions about the supply voltage at the radio will continue. It would be nice to display the supply voltage on the display below the "FLEX 6700" that is there currently.

To avoid un-necessary overhead it could only be updated ever minute or so. Has this idea been considered already?

Regards, Al / NN4ZZ

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Steve - N5AC, VP Engineering / CTO

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We have discussed this, but have been putting it off while we work on other things. We also have access to the current consumption in the radio which allows us to measure the resistance of your power cable (assuming no power supply sag) when you transmit. I thought it would be useful to check this on transmit and if the resistance is too high to report this as a problem in your setup. For example, if you went from 2 to 18A on transmit and the voltage went from 13.8 to 12.9 on transmit, your line resistance is 56.25mOhms which is responsible for the sizable voltage drop. On the other hand, if you go from 13.8 to 13.6 with the same current, your line resistance is 12.5mOhms which is much better. We'd have to decide where to warn people that it might be too high for transmit, etc.
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Al / NN4ZZ

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Good to hear....agree this is not a priority but might also help reduce your support calls. Regards, Al / NN4ZZ
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Reggie-k6xr

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A search turned this thread up so I will add to it. 6500 latest ver ssdr. voltage at keydown is 13.97V. Test into dummy load.
80,40,20,17,10,6 all 90 watts. 30 is 84w and 15,12 is 97w.
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Charlie

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I have the same problem with my 6500.  Sent it in to have checked per Tim's recommendation and the tech that worked on it said that it was fine and the lower power output was a software problem in the current version.  It is suppose to be corrected in a later version.
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Tim - W4TME, Customer Experience Manager

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Charlie is correct.  There is a software defect in v1.3.8 that dropped the power output that will be fixed in v1.4
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Steve - N5AC, VP Engineering / CTO

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We lost 0.5dB in software.  It is fixed in v1.4, due out soon.
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Steve Gw0gei

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I have only run 1.3.8 so far with my new 6300 and it is now reading under 90w on all bands - usually around 85w. Not an issue really as I run a valve amp that does not require much input. However I am sure that I was getting 95 to 101 on the bands when I first ran it. Is the software issue likely to have caused the drop in power over a few weeks of use? Or did I dream the higher output power?! Not a major issue for me but if it's not the identified software issue I will start checking my voltages. Nice to see a company being honest and acknowledging issues which are being worked on - in sharp contrast to my experience with Icom previously. I look forward to trying 1.4 when it is ready.
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WW1SS - Steve

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How soon will it be out???
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Ed.G, Software Engineer

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In v1.3.8 there is a bug in the TX Signal Chain that results in 0.5dB of attenuation. This is an initialization problem within the Hardware ALC attenuator. For v1.3.8, If you enable the Hardware ALC, it is possible that this will reset the offending attenuator and you should get full 100 Watts out.   This bug is fixed in v1.4.


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KY6LA - Howard, Elmer

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1.4 will be out when they release it into the wild!!!
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Steve W6SDM

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I use DDUtil to monitor my voltage and temperature.  It's not as accurate as measuring at the back panel with a good multi-meter, but it will give you a constant readout.  If you have a bad power cable or connection, you will see it.  You will also see how much of a drop you get when you're rig draws current when being keyed.  Once when I was experiencing strange problems with my 5000, I ended up replacing a faulty power supply once I realized what was happening.

It would be nice if the voltage and temp showed up somewhere on the main form of SSDR.