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Here is a schematic of a UHF Pre-Amplifier using the NE34018 HJ-FET device.
You may be able to plug other devices into the same circuit with minor tweaking.
The NE34018 HJ-FET device gives excellent performance, is reliable, cheap and pretty stable.
This is the device I used the most for repeater and satellite use. You do not have to etch a circuit board. You
can mount all the components right on top of the board. Or just etch a hole where the device will be placed on mount everything else on top.
It is very important that the source leg chip capacitors are right at the legs of the HJFET.
Don't try to use cheap or larger capacitors there. Use a low power grounded soldering
iron - say 15 watts.
Parts List
- NE34018 HJ-FET
- 2pf mylar capacitor
- 3/4" x 1/4" x 3/4" piece of silver plated wire or copper if you must
- 25pf high Q variable capacitor
- 2 - 200pf surface mount chip capacitor
- 75ohm 1/4w carbon resistor
- 1:1 transformer
- 220pf mylar capacitor - not critical
- 100ohm 1/4w carbon resistor - if you need it
- 27ohm 1/4w carbon resitor
- 3Volt zener diode
- 200pf mylar capacitor
- 200ohm 1w resistor
- 2 - .1uf ceramic capacitors - not critcal
- 1 3/4" x 2 1/4" piece of circuit board
- a box to put it in
- 2 connectors
Sorry for the poor photos, the device is in there somewhere!!! You should cleanup the flux when you are finished. I got lazy.
Here's a schematic of a design using the NE34018 HJFET device. (approx 15db gain)
Here are some pictures of this design using the NE34018 HJ-FET device.
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