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Preamp module 2N5109 manual

This is very simply preamplifier module with 2N5109 transistor based on W7IUV design. You can use it as high IP preamplifier, buffer amplifier or small driver. Gain is up to 18dB and there is also build in variable ATT. You can easy set gain as high as you need! As well you can set right transistor bias with multi turn potentiometer. Two relays offer bypass switching if there is no power supply.



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Applications
Parameters
Schematic
PCB
KIT Assembling
Part list
Transformers
Tunning
Article


Applications

- High IP RX preamplifier - RX antennas
- Buffer amplifier

- Driver amplifier



rx preamp module 2n5109 qro.cz hamparts.shop


Parameters

- Supply voltage 12 to 14 V  HIGHER SUPPLY VOLTAGE NEEDS COOLING AND RESISTORS TO RELAYS
- Supply current up to 180 mA - include relays current

rx preamplifier by qro.cz hamparts.shop



rx preamplifier by qro.cz hamparts.shop



gain for 50 kHz to 1 MHz

measure rx preamp module qro.cz hamparts.shop

gain for 1MHz to 70 MHz

measure rx preamp module qro.cz hamparts.shop

Input SWR, S11

measure rx preamp module qro.cz hamparts.shop


Schematic

schematic rx preamp module qro.cz hamparts.shop


PCB

pcb rx preamp module qro.cz hamparts.shop



KIT Assembling

rx preamp module 2n5109 kit qro.cz hamparts.shop



pcb after assembling all the parts

rx preamp module assembled pcb qro.cz hamparts.shop



Insert two multi-turn trimmers, there is 2 k Ohms (202) and 200 Ohm (201) and insert resistors



Continue with capacitors 100 nF (small yellow 104), two blue electrolytic capacitor

BE CAREFUL on polarity! minus (-) is marked on capacitor, plus (+) on PCB









Insert 1N4007 diode (please follow polarity on PCB), two Omron relays and small inductor (L3)







Transformers

- There is one FT50-75 ferrite core
- Ferrite has got 5 turns of bifilar winding

- Clean coating from the ends. Place wires in right order like on the pictures
- Check it again :)

transformer core

transformer core

Cut/fold wires in half

transformer core cu wire



Make bifilar winding - you can use small PVC tube and ACU drill

transformer core cu wire

transformer core cu wire

transformer core cu wire

transformer core cu wire




Insert transistor to the radiator and wind output transformer

use screw driver to open radiator a little bit if needed

there is small ferrite core T50-75, wind 5 turns of bifilar wires



PLEASE measure start and end of both windings, insert it into the PCB in the right order!


Part list

NAMEPARTVALUE
D1 diode 1N4007
C1, C18 - C19, C21 - C23, C25, C28, C35 capacitor 100nF 100V
C20, C24 capacitor 10uF to 100uF
R1 resistor THT 150R
R5 resistor THT 2K7
R6 resistor THT 680
R7 resistor THT 1K
R8 resistor THT 6R8
R9 resistor THT 12R
T1 heatsink heatsink TO39
T1 transistor 2N5109
RE11, RE12 relay G5V-12
ATT trimmer 200Ohm
R4 bias trimmer 2KOhm
L1, L2 ferrite core FT50-75
L3 inductor radial
Wire wire 0.45 mm wire
wago 2-pole wago
IN, OUT connector SMA




Tunning

- There is nothing to tune on RF side. It is wide band amplifier.
- You only need to set right TRANSISTOR BIAS current and Gain

disconnect jumper JP1
connect mA meter there (200 mA scale is fine)
connect supply voltage you want - from 12 to 14 V
turn the resistor trimmer R4 (BIAS) and set bias current you want - it should be from 60 to 85 mA - depends on application
then connect jumper short back again

- With the resistor trimmer (ATT-TRIM) you can set amplifier gain as you need

from 0 to about 18 dB
turn the ATT-TRIM (201)


Article

   Read article from W7UIV.

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