On Wed, Jan 10, 2024 at 06:34 PM, W7WRX wrote:
If your 8k Ultra sags down to 4800 volts you have something wrong.? Possible weak AC line, or failed Oil caps.? I used a Fluke HV probe and mine sits at 5900 volts.? panel meter shows 6000.? ?At rated 5kw output it sags to 5500.?
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The 8K has a very small power supply. Its only a 1 AMP CCA transformer with 2-amp surge.? It was designed for 5kw pep on SSB and no more than 1 amp plate current in Data modes. That is RIGHT IN the manual.? ?Its rated at 8k INPUT to the power supply.? NOT output.?
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This is a good example of my exact point.? The amp will make 7000 plus pep with video all over the net showing this.? It does this on SSB with a 2 amp transformer That I can pick up and walk away with.
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Which of the 7 versions of the 8K ultra are we talking abt ?? ?The 8k manual I have sez...." 5400 dc no load.? Sags to 4800 vdc with a 1.25 amp CCS? cxr".? On the manual I have, they used? a 6000 vac xfmr...and a resonant chole input. No load B+ is .9? X 6000 = 5400 vdc.? The manual I have sez 3.5 kw pep out...on the higher B+ position..... and 2.5 kw out on the lower B+ position ( data modes).
One thing u gotta be careful with on the 8k..... it uses 5 x 20K? @ 100 watt? wire wounds in series for bleeders.? Each wire wound dissipates 60 watts? (300w in total).? If any one of em goes? open, all hell breaks loose.? Then it turns into a capacitor filter, and B+ is now 6000? X 1.414 =? 8484 vdc.? Something to be aware of.? In normal operation, 300 watts of bleeder is used to make the choke look like a choke.?
Are u saying ur 8k sags to 5500 vdc.... while talking on ssb ???
