2SC2879 datasheet question

[nomadradio]

The first chart is the power gain. Compares drive power to output power.

Second chart shows how IMD distortion is lowest at roughly the 60-Watt output level, higher below and above that.

73

 

[2NC995]

The first chart is the power gain. Compares drive power to output power.

Second chart shows how IMD distortion is lowest at roughly the 60-Watt output level, higher below and above that.

73

Got that...by why two freqs listed on the first chart?

 

[nomadradio]

Intermodulation distortion is the mixing together of two separate signals. If they mix, the audio quality suffers. An amplifier should feed out just what you feed into it. They need to remain separate coming out of the amplifier, the same as they came into it.

But bigger. When the two input signals "intermodulate" you get distortion.

Only way to test for this is with two separate input signals.

Or more than two. The measurement is a ** LOT ** easier to make with only two.

This "mixing" behavior is different at different drive levels. That's what the graph is about, to show how the IMD changes from one input level to another.

73

 

[blasphemy000]

Got that...by why two freqs listed on the first chart?

They use a 2-tone signal for the power/gain chart (IP vs OP) because the transistor is meant for use in SSB linear applications, according to the datasheet, so output power is specified in PEP under those conditions. It also allows the use of the same test setup for both the power and IMD tests.

 

[2NC995]

They use a 2-tone signal for the power/gain chart (IP vs OP) because the transistor is meant for use in SSB linear applications, according to the datasheet, so output power is specified in PEP under those conditions. It also allows the use of the same test setup for both the power and IMD tests.

That’s pretty much what I was trying to ask in my post, but I certainly enjoyed learning about IMD along the way!