[Amps] Westinghouse BC Ammeter QX-37

[Steve Thompson]

Bill Turner wrote:
> 
> ORIGINAL MESSAGE:
> 
> At 12:23 AM 1/9/2006, Steve Thompson wrote:
> 
>> Most amplifiers can achieve 65% efficiency but will be noticably cleaner
>> if they're correctly tuned/loaded for 50-55%.
>>
>> Steve
> 
> 
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> I'm sure your statement is correct in a technical sense, but is more 
> "cleanliness" necessary? I prowl around the bands a lot and the only 
> evidence I hear of unclean amps are from ones that are overdriven. 
> Overdrive can happen in a class A amp too, so what does one gain by 
> running at 50% efficiency?
> 
> In other words, if an amp already meets FCC specs for IMD, what does a 
> five or ten dB improvement get you?

For high order IMD - which is what affects your neighbours most, the 
improvement can be higher. It gets you a slightly higher electricity 
bill, and (hopefully) thanks and respect from your fellows.

> 
> It makes me think of Charlie Brown's statement: "It's like wetting you 
> pants wearing a dark suit. It gives you a warm feeling but nobody 
> notices." :-)

I know that one well (not literally, I hasten to add!) from charity 
work. The truth is that people do notice, they just don't tell you.

I see two 'problems' - it's easy to monitor and tune for maximum output, 
much less easy to monitor and tune for good linearity. It's also all but 
impossible to convince people that it's good to run 20% less than their 
amp is capable of, and that it won't change what they can work (ok - I 
know the eme guys can show me different, but it's true for most contacts 
on most bands). I wonder if there's a gender difference in attitudes?

Steve