SSDR V 1.8.3 Update Problem

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  • Problem
  • Updated 3 years ago
  • Solved

I have a Flex 6300 and have been running SSDR 1.6.21 successfully for many months, and am able to drive my amp to full power.  I decided to upgrade to SSDR 1.8.3., which went successfully, but now when I use the amp, I get a short burst of full power and then it drops back to almost zero.  In TUNE mode it will drive to almost full power, but as soon as I stop tuning and try to operate, it drops back to a very small power.  If I don't use the amp, the 6300 seems to put out power normally, but only 75 watts max.  The input SWR on the amp is low, but I used the autotuner to make sure.

I subsequently dropped back to SSDR 1.6.21 and everything returned to normal, with full power out of the amp getting about 85 watts max from the 6300.  I notice that there was a "fix" which relates to cutting back power on adverse SWR, and I'm wondering if this is causing my problem.  I'd like to be able to upgrade.

Anyone else seeing this?

Paul - AA6Z

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Paul Burton

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Posted 3 years ago

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KY6LA - Howard, Elmer

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You are seeing @500W no foldback but @600W fold back to zero

My best guess is that you still have RF in the shack but the ferrites are reducing the RF in the shack when you are below 500W so the RF in the shack does not reach a threshold where it may cause fold back. 

Solution: More Ferrites in more places (Power leads and anything else that can pick up RF from common mode currents) and a better grounding system to reduce current loops... Suggest you read my "How to build a Quiet Station" paper posted in this community...

@Steven  - since the code works well for virtually all modern Solid State Amps - you are likely totally wrong about your guess that there is an error in the code relating to the foldback circuit.  

My Expert 2k-FA Amp is capable of running 2,300+W key down.  During beta tests there was NO FOLDBACK whatsoever running this amp so clearly the software is working as it should.  But then I have spent a lot of time and effort to make sure there are minimal common mode currents on my leads...

Also it would appear that you do not understand the benefits of introducing the foldback feature.  Flex PA are very robust. However there may be extra-ordinary circumstances (such as an antenna failure) where having an extra layer of protection on expensive final transistors would be quite beneficial to most people.  I do agree that a simple solution might be to make it optional for those who don't mind blowing finals and have older tube amps with lots of RF in the shack... I suspect however, if your finals blew, then you might one of the first to curse Flex for not having a foldback feature and/or making it optional.    Personally I would rather fix the RF in the shack issue and save my finals...

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Terry Tankersley

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1.8.3 works fine with my 6500 and ALS-1300, I will try it with my SB221 later this weekend.

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