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3CX1200Z7 maximum safe grid current
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I have an AL-1200 with the 3CX1200Z7. The tube has a grid dissipation rating of 50W, but I've found no spec for maximum grid current. On page 5 of the AL-1200 manual it says do not exceed 300ma during normal operation of this amplifier. On page 14 in step 11 of the CW tuning procedure it mentions both 300ma and 250ma. I have been running my AL-1200 at 200ma grid current because I don't want to risk damaging the tube, but I can't get 1500W output on any band at 200ma grid current. I would like to know what is actually the maximum safe grid current for operation of this tube.
I noticed the last time Ameritron was advertising the AL-1200, the price was for an amp without the tube. I took this as an indicator that the tube is no longer in production. Is this true? Is anyone re-building the 3CX1200Z7? Thanks! 73, John, K9MM |
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The amplifiers were sold without tubes because they cost too much and killed amplifier sales.
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The 3CX1200A7 can also be used in place of a 3CX1200Z7. Look here to see the spec sheet of both tubes: 73, Dave, w6de -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of John, K9MM via groups.io Sent: 14 August, 2024 21:44 To: [email protected] Subject: [ham-amplifiers] 3CX1200Z7 maximum safe grid current I have an AL-1200 with the 3CX1200Z7. The tube has a grid dissipation rating of 50W, but I've found no spec for maximum grid current. On page 5 of the AL-1200 manual it says do not exceed 300ma during normal operation of this amplifier. On page 14 in step 11 of the CW tuning procedure it mentions both 300ma and 250ma. I have been running my AL-1200 at 200ma grid current because I don't want to risk damaging the tube, but I can't get 1500W output on any band at 200ma grid current. I would like to know what is actually the maximum safe grid current for operation of this tube. I noticed the last time Ameritron was advertising the AL-1200, the price was for an amp without the tube. I took this as an indicator that the tube is no longer in production. Is this true? Is anyone re-building the 3CX1200Z7? Thanks! 73, John, K9MM |
开云体育I use 300 mA as a max at 4kV B+ in CW. The issue with grid dissipation is that the tube’s input impedance needs to be known and it’s not a trivial value to determine. I trust Ameritron’s notation of 300 mA and simply use that73, Kim N5OP "People that make music together cannot be enemies, at least as long as the music lasts."?-- Paul Hindemith On Aug 14, 2024, at 5:51?PM, Dave w6de <w6de@...> wrote:
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