[Amps] Can I cool too much the tubes?

[Steve Thompson]

I've observed this across a wide range of class AB linear 
amplifiers - device dissipation is very roughly constant between 
10 and 100% output.

With a tube amp you can adjust the tuning to get higher efficiency 
at lower output power, which will reduce the tube dissipation as 
well as giving the PSU an easier time.

Steve

> Gentlemen,
> 
> You should take a look at the plate dissipation at the reduced power levels.
> 
> In my amp, as the power output drops back, the efficiency drops at a faster 
> rate on some bands.  Which means that running the amp at half power, for 
> example, as is the current rule of thumb for RTTY operation, may not 
> actually reduce the effective plate dissipation very much.
> 
> Of course, one point does not make a trend.  But it's easy to make the 
> calculation and then a guy can KNOW rather than just guess.
> 
> And if we were perhaps talking about an SB220, that transformer is pretty 
> light weight to begin with, and a guy would definitely want to check the 
> efficiency there.
> 
> Hope to see you in the SARTG.
> 
> 73/jeff/ac0c
> www.ac0c.com