25 watts is NOT enough drive to get the load control up of full capacitance. ?You need to drive the amp with much more power. ?Once you head around 50 watts the load control will begin to go higher off 1 on the dial. ?80 watts or more is typical drive for a pair of 3-500 tubes.
On Monday, April 28, 2025, 8:48 AM, Fran?ois via groups.io <18471@...> wrote:
Make sure the input circuit is lined up with the proper output band.
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On the input side, it seems fine. I'm driving L7 with an FTDX-3000. I performed a TUNE, forcing the RLY relay to close, and I have a VSWR of 1.
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Test conditions:
¡¤???????? Idle: 2600 V, 140 mA for a 6.5 V bias.
¡¤???????? At the output, I'm on a 50-ohm dummy load; the L7 doesn't indicate any output VSWR.
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However, I just noticed that on the 7.100 MHz band where I was testing, the LOAD capacitors (C4, C47) are at their maximum. I checked; they are indeed in parallel on this 40 m band. The amplifier can't output more than 400 W.
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On 3.650 MHz, the same problem: this LOAD capacitor is at its maximum. The amplifier peaks at 400 W for 400 mA at 2300 V and 25 W input.
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At 14,200 MHz, the LOAD capacitor is at its midpoint, and a 25 W input produces 500 W (2300 V, 390 mA).
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I don't know what to think anymore.
De la part de mike repinski via groups.io
·¡²Ô±¹´Ç²â¨¦?: lundi 28 avril 2025 13:37
