160M Receive Pre-Amp

After deciding to operate on 160M I was searching for a pre-amp to use with my newly built 160M receive only loop.

It was recommended that I try the Pre-amp designed by KD9SV this is a pre-amp with variable gain so i set about trying to build an example.

The major problem i found was locating a copy of the schematic diagram various web links mentioned in such publication’s as the ARRL hand book no longer worked.

After putting out a request on the topband contest news group I received many offers of a copy of the required information.

I have received many e-mails requesting copies of any information that I received. I did not know what interest I had stirred by requesting information on this preamp. I have now made this information available here for all to share.

Please note that I accept no responsibility for the design or the suitability of this preamp’s use.

160m-Pre-amp

160M Receive Pre-Amp

Download the above as a PDF file

80160

Switchable 80/160M Receive Pre-Amp

Download the above as a PDF file

board

You will need to adjust the actual size of the board with a graphics program so the size is 64mm wide by 40mm high.

Parts List

C1 COMPRESSION TRIMMER 50-300 pf
C2 COMPRESSION TRIMMER 50-300 pf
C3 . 05uf
C4 . 05uf
C5 . 05uf
C6 . 05uf
capacitors are disc ceramic
R1 8k2
R2 22
R3 750k
R4 16k
R5 47k
R6 100
R7 8k2
R8 100
R9 1k
Resistors are 1/4 watt
R10 10K panel mount potentiometers with ON/OFF switch
CR1 IN914( or equivalent) silicon diodes
DS1 LED
CR2 IN914( or equivalent) silicon diodes
Q1-3SK88, 40673 or ECG/NTE 455 (other dual-gate MOSFETS will work as well)
L2, L3 FT50-61 TOROID
Switch 1 Part of potentiometers
Switch 2 SPCO
Printed circuit board FAR Circuits

L2-FT50-61 TOROID 22 turns # 26 enameled copper wire tapped at turn 11 with 2 turns wound over L2
L3 FT50-61 TOROID 22 turns # 26 enameled copper wire tapped at turn 11 with 2 turns wound over L3

Ready built and tested units from Gary KD9SV.