Can I replace BF197 with BF199 transistor in this VHF amplifier?

Hi there,

I'm doing this amplifier for the last stage of my transmitter.

http://www.electronics-lab.com/proje...009/index.html

I wonder it's suitable and i'm trying to replace BF197 with BF199 transistor. I'm wondering if it'll work for 100Mhz

Alex

Hi,

Yes, you can use BF199 instead of BF197 transistor. It will also amplify about the same around 100MHZ in that circuit your link shows because its unity gain transit frequency is around 400-500MHz.

Just another question,

When i'm dealing with VHF, the only parameter that i need to consider in the transistor is the unity gain transit frequency? or there's other parameter in different transistor that i need to consider as well.

Alex

Other parameters are: Gain, Noise Figure, Linearity, Stability, Supply voltage, Current consumption.

I think freeacale's LDmos transistors are good chioce for the VHF PA design.
I have completed many PAs wroking from 30mhz to 500mhz, All used freeacale's transistors.
Btw, Point 9's transistor for VHF is a another good chioce.