Hi San,
In my experience, the L4B can be safely loaded to maximum output, which is
about 1400-1500W. You can't get any more power output than that because the
two 3-500Zs won't load any higher. However, I'd be reluctant to run the
amp at 1500W output key-down for extended time (e.g., for RTTY), because of
cooling limitations. One of the great things about the L4B is how quiet it
runs, but the price is for cooling that doesn't have much reserve capacity.
For typical SSB use, however, you shouldn't have any trouble.
I'm not sure about the L7, however. The RF deck in the L7 is much lighter
duty construction than that in the L4B. I'd be careful about pushng the L7
beyond it's specified ratings.
73,
Jim Garland W8ZR
The At 01:14 PM 12/2/2002, you wrote:
>Would like opinions about what parameters the PS and RF deck components of
>the L4B/L7 can handle power-wise. Knowing the manual states about 550ma
>final plate current with low voltage about 1800v and high voltage in the
>range of 2500 v DC, when one figures the input power and 66% efficiency you
>end up with OUTPUTS of about 650 watts in CW position and 900 in SSB
>position. That is what I and most people get when tuned up correctly. Now,
>since that is only about 325-350 watts dissipation in CW mode and 450 watts
>in SSB position, it seems the 3-500Zs have room for more input power to get
>to the 1000 watts rated dissipation. That would mean a linear producing 2500
>watts input could put out 1600 watts with 900 being dissipated IF the
>components can take it. Can the L4B/L7 be run at say 750ma at 2500 volts(
>1875 watts input )with output of about 1200 watts without problems with the
>PS transformer/components and will the RF deck handle that input? Seems
>like years ago I ran the L4B at 1200 output without problems but the 750ma
>plate current bothers me now. Just need some opinions of how much the
>linears are overrated on components, etc. Can the L4B take 800-900 ma input
>plate current with good 1:1 swr? Thanks for any thought from those who have
>tried the "power creep" on the L4B/L7 amp. San K5YY
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