Intermittent drop of power output

  • 1
  • Question
  • Updated 2 months ago
Flex6500, Maestro, Windows 10, SSDR 2.3.9  I am experiencing an intermittent random drop of RF power output whilst transmitting on CW. (presume it would be the same on SSB) It typically drops to about one third of the set output power level.  It lasts for a few seconds but always recovers then may do it again or continue to remain at the correct power. It is intermittent and difficult to recreate under test.  I cannot tie it to any specific PA temperature being monitored via FR Stack and there is no input DC voltage level change. This happens on a dummy load as well as external ant and the SWR does not alter when the power drops.  I have confirmed that the power does actually drop using an external power meter and not some kind of meter indication fault.

Unfortunately a Flex service centre would have to spend some dedicated time trying to recreate the problem with the risk of declaring it ok.  I have carried out a factory reset on the rig and the effect happens when either using it with the Maestro or PC.

Any thoughts or suggestions of further tests would be useful.
Photo of Mal G3PDH

Mal G3PDH

  • 48 Posts
  • 2 Reply Likes

Posted 3 months ago

  • 1
Photo of Martin Ewing AA6E

Martin Ewing AA6E

  • 292 Posts
  • 58 Reply Likes
Is it a function of the power level? Do you see the effect if you keep the key down continuously? (On dummy load)
Photo of Mal G3PDH

Mal G3PDH

  • 48 Posts
  • 2 Reply Likes
Martin, it seems to happen at any power level. I carried out checks with key down at 10w into a dummy load. On first test it dropped down to about 3w after a minute or so and then recovered. A further 4 tests of a few minutes each with the PA temp ranging from 33 to 60 degs it did not occur at all so it is extremely and annoyingly intermittent. Have also tested by reverting to ssdr version 2.2.8 just in case it was anything to do with the power stabilization algorithms in 2.3.9 but it did the same so now back on latest software again. Will continue key down checks but reluctant to send off for repair until it is a more definite repeatable fault.
Photo of WQ2H - Jim Poulette

WQ2H - Jim Poulette

  • 118 Posts
  • 29 Reply Likes
Is your external power supply maintaining a minimum of +13.8Vdc? If there's any droop - that could be an issue. Good luck !

73
Jim, WQ2H
Photo of Sergey, R5AU

Sergey, R5AU

  • 846 Posts
  • 111 Reply Likes
Hi Mal !
could you check please power supply before fuse and after fuse (then power drop)with Flex meter  from here http://www.denzone.com/
How looks like transmitted signal quality at time power issue ? 

I wanna to say that on my 6700  power coming down on 10% roughly like  on any others modern solid state PA in case temperature up, i am not care
(Edited)
Photo of Mal G3PDH

Mal G3PDH

  • 48 Posts
  • 2 Reply Likes
Many thanks for all your suggestions, I will try a different PSU and take a close look at the DC voltage levels but with the voltage adjusted to 14v on RX and 13.7 or 13.8 on TX the drop off happened again in QSO's today. I did not see any voltage issue at the time. Using a GSV3000 psu. Will alsoinvestigate the Flexmeter software.
Photo of Mal G3PDH

Mal G3PDH

  • 48 Posts
  • 2 Reply Likes
Many thanks for all your suggestions, I will try a different PSU and take a close look at the DC voltage levels but with the voltage adjusted to 14v on RX and 13.7 or 13.8 on TX the drop off happened again in QSO's today. I did not see any voltage issue at the time. Using a GSV3000 psu. Will alsoinvestigate the Flexmeter software.