On Wed, Apr 16, 2025 at 08:20 AM, KG2RG wrote:
Jim, W6SAI, best book around!!! Sometimes called the West Coast book, sometimes called the big green book, the Radio handbook by William ?I Orr, great stuff!!!
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Heathkit and Ameritron were able to convince Eimac to give a 1 year warranty. This was also back when tubes were plenty and cost less. ?
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the question is what happens when you run a Eimac at Ip at 550mA CW? You exceed the Eimac specs by 37.5%
what is the most fragile part of a tube? the grid, and it¡¯s rated at 20W dissipation.?
so what happens at 200mA of Ig with 100W of drive? ?
the drive impedance of the 3-500Z is 115 per Eimac.?
Grid dissipation is peak voltage X grid current.?
at 100W drive, peak grid voltage is 150V
150x0.2=30W. At 30W, max specified Grid dissipation is being exceeded by 50%?
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As I mentions, I do run a little over for SSB since voice modulation duty cycle is 50% or less, so I may run around 150mA of grig and a little over 400mA on the Ip. But for CW, I do not exceed the Eimac specs. I also run it with just a little color to activate the getter.?
###? ?On the SB-1000,? AL-80B, they rate it at 1000w? pep out on? SSB? (550 ma).....and? only 850 watts out on CW (450 ma).??
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