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TOPIC: Low Power Output on ALL Bands--Why?

Low Power Output on ALL Bands--Why? 25 Sep 2021 16:17 #1

Just as the title says--
160 meters--89 watts
80 meters--26 watts
40 meters--30 watts
20 meters--65 watts
17 meters--65 watts
10 meters--85 watts

We get the same results on both versions of the software (ExpertSDR3 0.9.0 alpha and ExpertSDR2 1.3.1 update 9)
Power corrections are all set to 100%
Same results whether using the TUNE or SSB mode.
Any help most appreciated.

Regards,
Larry
n7zdr
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Low Power Output on ALL Bands--Why? 25 Sep 2021 20:07 #2

  • Svante
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Input power? 12 V 12.5 13 V 13.,8V ? It makes a Big differens.I use 14.2 volt in standby and when I transmit it drops to about 13.5V. When tuning I see from 97 to 107 watt
sm6usu Svante.
sm6usu
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Low Power Output on ALL Bands--Why? 26 Sep 2021 00:51 #3

Great thought Svante! I just checked it and even hooked up a variable power supply at 14.2 and saw no differance compared to the 13.6 volts running on and back wall.
I sure hope some others will chime in on this as its a bummer on 40 and 80 meters.
Regards,
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Low Power Output on ALL Bands--Why? 26 Sep 2021 14:22 #4

  • DL5RK
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Larry, the same here...
17m 70W max, internal shows 110W SWR 1:1 Dummy
My output is 70-85W across the Bands. The internal Meter is showing wrong things (PWR wrong, SWR wrong, Volt wrong).
I have to use external meters.

My Sundsdr2 Pro and QRP in the past have done this very good, no external meter needed!
Maybe EE give us the answers, few customers asked the same questions in the past but the answer was not official...

73
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Low Power Output on ALL Bands--Why? 28 Sep 2021 01:38 #5

  • KR9Q
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Mine does the same thing. Input from power supply is 14.6 at idle. Full tx is 14.1 with 70-85W output across bands into a dummy load. I have often wondered if the very long power cord affects this, but at the same time, it seems to be of heavy enough wire diameter to not cause problems. So far, have not discovered remedy.
73
Jack
KR9Q
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Low Power Output on ALL Bands--Why? 28 Sep 2021 14:52 #6

  • Svante
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sm6usu Svante again. test to dummy load 14.2 V standby 13.6 volt tx mode. 80m 98.8 watt 40m 101.1 watt 20m 108.0 watt 17m 106.9 watt 15m 110.3 10m 94.2 watt
14.4V standby 13.8 volt tx mode 80m 98.8 watt 40m 102.3 watt 20m109.2 watt 17m106.9 watt 15m 111.5 watt 10m 95.4 watt
sm6usu
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Low Power Output on ALL Bands--Why? 28 Sep 2021 15:47 #7

  • Svante
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Hope that we can get numbers from more users with external meters. I do not have any meter except the internal.
sm6usu Svante
sm6usu
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Low Power Output on ALL Bands--Why? 24 Oct 2021 16:55 #8

Hello good afternoon, I have the same problem maximum output power 70w pep, the meter sunsdrdx says 110... if I try to remove agc or any other option, modulation distortion. It's frustrating to start with this rig and have so many modulation and power output problems. I don't know what to do ... If someone can give advice I would be grateful.
73
Franc
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Low Power Output on ALL Bands--Why? 24 Oct 2021 20:16 #9

  • Svante
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Yes Hmmm. I only have the internal meter.,When using agc I never se mpore then 95 watt and mostly 60 -80 watt I have then experimented with different microphone and external soundcard vac and all that.. If I run with limiter instead of agc I see in the internal meter 100 to 135 watt and that is changing a lot depend how much mic gain I use. (Be careful ) When using agc it is whery hard to get a dx contact but when using limiter and about 130 what( according to internal )meter I got dx contact much much more often. My old 718 have easier to make dx contacts then sunsdr2 dx when using agc that is my opinion.. It feeels more an 80 watts tranceiver then a true 100 watt tranceiver. But I like all others what this tranceiver can do and the quality of reciving.
Sorry about my english
Svante sm6usu
Svante sm6usu
sm6usu
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The following user(s) said Thank You: giru22

Low Power Output on ALL Bands--Why? 24 Oct 2021 22:06 #10

Hello Svante, I was thinking if the problem is my old intel i5 2400, I will try to test what you say agc off limiter activated. Hopefully this of ssb and power output with perfect modulation could be solved. I will have to look for ldmos amplifier ...
73
Franc
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Low Power Output on ALL Bands--Why? 26 Oct 2021 12:27 #11

  • kc2rgw
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I have variations in output levels band to band, but roughly in the high 70s at worst.

I also have three meters and none of them agree and I do not have lab instruments to calibrate them.

I’ve never had a situation where 70 vs 100W would make any difference to anyone.

Why the OP has 29W on 80m I can’t explain, definitely something wrong, but what is the load the OP is using to test? What is the meter used? What mode is the meter in?
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Low Power Output on ALL Bands--Why? 26 Oct 2021 14:17 #12

Just to put this to bed---We had a remote session where they re-calibrated the power out settings. They set all levels to 100 watts on the radios meter, however the LP-700 with coupler on the output of the radio still shows 60-70 watts output into the 50 Ohm load (I will trust the lp-700 and Wavenode meter first). You are right about 70 watts compared to 100. Point being--- are we are buying a 100 watt rig or 70?
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Low Power Output on ALL Bands--Why? 26 Oct 2021 15:03 #13

Good afternoon, the difference is to have paid 100w and have 70w .... and if you want 100w, just nfm or turn off the agc and go out into the air distorted.
Or you can have an om power amplifier like me, and even if you do not need the output at full power, because with the sunsdr in ssb you can not see it at maximum.
So I hope it resolves
Greetings
Franc
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Low Power Output on ALL Bands--Why? 09 May 2022 19:58 #14

  • N0BS
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Having just received a used but new to me SDR2 DX, I also noted low power output on all bands ranging from a best case of 89w on 160m to a worst case of 63w on 30m. The other bands are all in the 70w range. These power levels are as measured by an LP-500. I see the same values within 2 - 3 watts on 2 other wattmeters in the shack, so I have to believe these numbers are correct. Also, several other 100w class xcvrs in the shack all produce 100w on these same meters. I am using a 30 amp supply and the PS meter shows about 20 amps key down (TUNE slider at 100%). The power output meter in the software shows very close to 100 watts in most cases, so there is a definite disagreement here. The software "analog" meter display shows different numbers (higher) than the slide rule display - also disturbing. Just trying to rule out excessive PS voltage sag, I connected a DVM to the PS output and observed the voltages under no load (rx only) and key down. Under no load the DVM reads 14.14 and the software indicates 13.9v. However, key down, the voltmeter reads 13.2v and the software reads 11.2. What gives here? Why such a large difference? What voltage is the software displaying?
It seems that some users here are satisfied that this is not a problem. That's ok if you feel that way. Personally, it seems like a problem to me. It's advertised as a 100w radio.
I am guessing that most people drive an amp with these radios and there is no need to run 100w to drive the amp. Well, I plan to do that too, so I can live with it, but it just doesn't seem "right" to me.
I will be happy if someone can show me that I'm doing something wrong or provide a fix for this.
Aside from this and a few other minor niggles, I am finding the radio very nice.
Tnx, Tom N0BS
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Low Power Output on ALL Bands--Why? 11 May 2022 14:14 #15

  • KD8CGH
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N0BS
I see a similar thing. My measured supply voltage of my Samlex SEC-1223 with a Fluke multimeter is .4 volts higher than what the SDR2 DX reports on receive. According to my SDR2 DX the voltage drops from 14.0 on receive to 13.0 on 40 m CW transmit at 100% drive. The measured voltage at the supply drops .5 volts, from 14.4 to 13.9 under Xmit load. A resistance of .045 ohms in the wires, connectors and distribution box would yield a 0.9 V drop at 20 amps.
You have almost a volt of sag in your power supply and another 2 volt drop getting to the Xceiver. Both are double what I see. I would carefully check the route from the power supply to the SDR2 DX.

Here's what I see key down CW into a dummy load using a Diamond SX-200 SWR/watt meter. The meter claims to be good to UHF, but doesn't read at 2 meters. It's HF readings agree well with output from my K3 that was recently factory repaired and calibrated.
Band SDR2 meter ** note - SDR2 DX power reading drifts down with time
160 105 88
80 105 85
40 102 85
30 105 90
20 110 95
10 120 100
6 110 95
2 11.5 ??

There is some variation over a band. On 20
MHz meter
14.04 85
14.34 90
73
Bob KD8CGH
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