Efficiency of amps

[Heavy Metal]

what makes or gives the amp their efficiency and how do you do figure out the efficiency. For example Ameritron says 65% efficiency how did they determine that as well, just curious, again I know I ask some reall weird and sometimes stupid questions but who is going to ask them LOL and how many wonder themselves too.

Again as always thanks.

 

[Beetle]

The class of amplifier (A, AB, B, or C, generally) determines how efficient the design is. To determine efficiency you need to calculate how much power (E x I) the primary power source (wall socket or battery) has to supply and how much RF power (E x I) is put out at the amplifier output. Do the simple math and there you are.

 

[Heavy Metal]

Take it A is best and C is least efficient correct?


And Ameritron amps fall
Under which and heathkit SB-220 falls under?

 

[Beetle]

Google is your friend. And Class A is more linear, but class C is the most efficient of the four classes listed.

 

[bob85]

in theory class C should be the most efficient and A the least efficient in properly designed amplifiers,

on the other hand class C davemade clones are very inefficient when run on stock voltage when compared to conventional design AB amps so you can't always only look at the class of operation.

 

[Heavy Metal]

But class C also is most distorted too.

 

[Beetle]

Correct.

 

[Heavy Metal]

So AB is about the best you can achieve at this point.

 

[bob85]

That depends on what mode you want to use the amplifier on,
for fm class C is ideal, for AM/SSB class AB is ideal,

class A rf amps are often found in low level IF stages and sometimes in the PA stage of HF sets but most HF PA's are class AB.

 

[Heavy Metal]

Ok understood, I was wondering seeing Ameritron advertises @65% efficiency but some are saying heathkit SB-220 and SB-221 are more efficient with right mods and can produce @2kw or more depending on drive and drive can be run up to 200 watts. That's kinda insane or am I wrong?

 

[ExitThirteen]

They can't take 200 watts input, unless there's a swamping network on the input. You'd roast the tubes in short order. The SB-220/221's do best with about 75-100W drive.

Also, your efficiency goes down as you go up in frequency. That's also a factor. You may be 65-70% efficient in 160-40 meters, but once you get above 20 meters it starts going down. Get into 10 and 6 meters and you're going to be in the ballpark of about 50% efficient.


~Cheers~

 

[BBB]

The Swan Mark II amplifier with it's (2) 3-500z's was designed to handle the matching Swan 500CX transceiver that could do up to 300 watts PEP on SSB on it's own.

I have not tried that yet

 

[Heavy Metal]

Wow even 300 watts PEP that's still considerable power driving those 2 3-500z