[Amps] AL-1200 - MO Power??

[Scott McGrath]

Is it really worth stressing the amplifier for a <1Db gain in output 
power.   Also IMD will increase the warning is probably directed at 
preventing insulation breakdown in the secondary windings and/or eddy 
current problems with the laminations and hardware.

New Peter Dahl transformers are available so why not upgrade the 
transformer to one which has a 4KV secondary at rated input this would 
allow you to dial down the exciter and get a better sounding signal

- Scott

Tony Brock-Fisher wrote:
> I have had an AL-1200 for over a sunspot cycle. It has run well, but never quite made the 'full boat' in terms of output. 1300 watts usually is what I get. HV runs a tad low, around 3450 volts no load. I never drive it with more the 100 watts (don't have a rig capable of more than that stock, and no, I don't want to 'tweak' my Pro2 to make over 100 watts due to IMD concerns).
>
> I am tempted to rewire the transformer primary to boost the HV. If I wire it for 220 instead of 240, it would boost the HV to 3763V. 9.1% boost in HV would give me a 19% increase in Po for 1547 watts out (naturally I would dial back the Pro2 for legality).
>
> Yes, of course I have read the warning in the manual that says not to rewire the primary for more than 3700 volts.
>
> I'm assuming that this warning is because the voltage rating of the string of HV caps is only 3600 volts (8 x 450V). (Which seems like a pretty marginal design in the first place).
>
> Supposin' I was to add another cap to the string, with the proper bleeder resistor. Now the HV rating of the cap string would be 9 x 450 or 4050 volts. Total capacitance would go down from 210/8 (26.25 uFd) to 210/9 or 23.3 uFd - not a huge deal.
>
> Does anyone see any problems with this idea? Any other concerns with boosting the HV?
>
> -Tony, K1KP
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