[AMPS] 60Hz versus 50Hz in PA

[yo3ctk]

Hi Rich, Peter and all,

Concerning blower performance, this is what I found in an excellent
article by G8WRB in October QEX:

Free air-flow rate is proportional to N (rpm), therefore proportional
with f (Hz)
Cutoff back pressure is proportional to N square

I'm familiar with the problem reported by the SM amateur. I encountered
the same with a MLA2500 from USA, but with a twist: in addition to
reduced plate voltage (due to 220V versus 240V mains and no primary
taps), the main transformer runs pretty hot, even on standby. That means
the "idle" primary current is excessive, and that is likely the cause
for the mechanical noise, in addition to heat.

Conclusion: the price for second-hand equipment may be excellent in USA,
but no necessarily a good deal for EU hams.

73 de Mike, YO3CTK


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