Flex-5000 not getting 100w out on most bands

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  • Updated 2 years ago
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I have been off the air for a while but now need to sell my Flex-5000 to help pay for my 6400 that is on order. Today out of curiosity I hooked it up to my LP-100 watt meter and a Heathkit Cantenna dummy load and am getting wildly varying outputs and can't figure out why. Below are the readings I got today. The internal ATU is turned off by the way. Did a data base reset just to make sure that that is not the issue. Running the latest version of KE9NS PSDR There is one coax run to the LP-l00 coupler and another to the dummy load. The power supply is a Astron RS-35M.

         LP-100           PSDR

160 1.24:1 83W   1.2:1 89W

80 1.27:1 83W     1.0:1 89W

60 1.28 :1 79W     1.4:1 87W

40 1.29:1 81W      1.4:1 92W

30 1.28:1 81W      1.1:1 88W

20 1.27:1 76W     1.6:1 89W

17 1.26:1 73W      1.3:1 81W

15 1.26:1 74W      2.0:1 91W

12 1.23:1 72W      1.3:1 80W

10 1.22 :1 85W     2.1:1 100W

6 1.26:1 50W        2.5:1 82W

Does anyone have any thoughts as to why I am not getting close to 100W out on most bands? Also how can the output on 6M be explained that the LP-100 is showing?


Zack Schindler

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Zack Schindler - N8FNR

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Posted 2 years ago

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Dudley - WA5QPZ

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Official Response

To be able to draw 22 amps, you will need #10 gauge wire to keep the voltage up at that current.  And if you are using PowerPoles, maybe sure the pins are pushed in and best to use the 40 amp connectors, not the 20 amp connectors.   In PowerSDR  use the internal "Information"  window to give you the voltage and temperature of the internals of the radio ,  best and easiest way to know if you are getting enough voltage to the radio ..   Anything under 13.0 volts UNDER FULL LOAD ,  will be a decrease in RF output.  With all working correctly normally about .6 of a volt drop from RX to full output TX is normal...   If the supply itself is not dropping voltage, but you are at the radio ,  start looking for wiring or connection issues..   by the way,  the older Astron analog regulated power supplies are known for loosing regulation over time due to the regulator chip and pass transistors..   So just because it's an old power transformer regulated power supply ,  does not mean it's good forever and it's good to periodically check your connections at the rear of the power supply, many have issues starting right at the back of the supply ..  

I think that I still have an old Cantenna dummy load some where too, but there are some good commercial dummy loads available on Ebay at a reasonable price too..