I.F. Amplifier


IF Amp.

I.F. Amplifier

 

The original design has been modified by putting a couple of LED's in the source circuit of each Mosfet. The voltage drop across the LED's keeps the source voltage at about two volts. This results in a much greater AGC range. This arrangement was suggested by N6BIU. Thanks Jim.
The I.F. transformer primary has 18 turns, the secondary winding has 4 turns. The capacitors across the IFT primaries are 82pF. The input/output transformer has 12 turns, tapped at 3 turns from ground. This transformer is wound on a ferrite core. The mosfets are 3SK45's. The diodes in the product detector are 1N34's. I use a six pole SSB filter from a scrap CB. The centre frequency is 7.8MHz. The -6db bandwidth is about 2.5KHz.

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