JFet Selection

[linguist]

In the diagram attached I noticed they have a NTE452 JFet that is used for UHF/VHF applications.
Why do you think have they chosen it for this application being an amplifier, is it for signal quality reasons or just the gain available etc, or other reasons.

Is there a modern readily available equivalent so I can try it out?

Cheers

 

[Roff]

Spec-wise, **broken link removed** looks very similar to **broken link removed**.
I saw another Google result that said they were equivalent.

 

[crutschow]

JFETs can have good high frequency gain and noise characteristics, and that is why they are often chosen for high frequency amplifier circuits.

 

[Roff]

JFETs can have good high frequency gain and noise characteristics, and that is why they are often chosen for high frequency amplifier circuits.

This looks like an audio preamp to me. I think the OP's question was about the choice of a UHF/VHF JFET for an audio application. I'm assuming it is because it was available, and works.

 

[crutschow]

This looks like an audio preamp to me. I think the OP's question was about the choice of a UHF/VHF JFET for an audio application. I'm assuming it is because it was available, and works.

You are right. I didn't look carefully at the schematic.

JFETs are sometimes used in audio applications because they are low noise and have characteristics similar to a pentode vacuum tube with a high input and output impedance. And a UHF/VHF type JFET will typically work fine at audio frequencies also.

 

[linguist]

Thanks for the replies,

I thought it was a strange choice of JFet but maybe not from the replies.

I can get the 2N4416 mentioned.

Cheers

 

[RCinFLA]

JFET's are square-law devices. They produce less intermodulation distortion then bipolar devices.