>
>Hi Chuck,
>
>The club at my workplace recently picked-up an AL-82. So far it
>seems like a very nice amplifier.
see photo of arced AL-82 bandswitch on my Web site.
>It uses 2 x 3-500Z tubes which
>are considerably cheaper than the 3CX1200 and the 8877 tubes
>used in the AL-1200 and AL-1500.
The 3cx1200A7 is virtually immune to grid/fil. shorts. 3-500Zs are not.
>The 3-500Z's are instant
>on, so there is no waiting if you stumble across a pileup with
>your amplifier off. Unlike many other 3-500Z amps, the AL-82
>runs a fairly high plate voltage (3600VDC resting in the SSB
>position), so the amp is easily able to produce legal limit output
>with 100 watt rigs like the TS-850 we have at work.
>
>I have also used the AL-1200, and the engineering model
>of the AL-1500 (an old contesting buddy is a good friend of
>W8JI). Both amps worked very well (the AL-1500 engineering
>unit would run 2500 watts output key down, but I think it had
>a slightly larger than stock transformer in it). From my recollection,
>the AL-1200 performed similarly to the AL-82 (its been over 10
>years since I have used the AL-1200). The only caveats I can
>think of for the AL-1500 are the higher tube cost, sensitivity to
>excessive grid current (characteristic of the 8877 tube), and
>warm up time of the indirectly heated cathode. The AL-1200
>doesn't have the problem of grid current sensitivity, but it
>does use a pretty expensive tube. I don't recall if the 3CX1200
>tube used in this amp is instant on or not. I should also mention
>that the AL-1500 will require less drive power to reach legal
>limit (~65 watts versus ~100 watts) than the AL-1200 or AL-82.
>
>The other technophiles on the reflector may be able to fill you
>in on some of the finer points
The AL-1500 has a reputation for premature 8877 failure. It is the only
commercially built HF 8877 amplifier that uses no parasitic suppressor
whatsoever. see Figure 24 on my Web site. / The AL-1500 has no
cooling air on the bandswitch & tank inductors. .
cheers, Mike
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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