Matti Hohtola OH7SV Amateur Radio Projects

50 MHz "Door Frame" Loop Antenna (2021)
Mobile antenna location (2021)

80 meter Circular Polarization antenna comparison (2021)
Optimal 160 meter dipole height for NVIS (2021)
Optimal 80 meter dipole height for NVIS (2021)
Nanocrystalline Toroidal Cores Measurements (2021)

Dummy Load for JUMA TC (2021)
JUMA TC Turnstile Controller Rev D for Circular Polarization (2021)
Modern Dummy Load (2021)
40m door frame loop (2021)

160m full wave loop impedance versus height (2021)
160m full wave loop gain versus height (2021)
80m full wave loop impedance versus height (2021)
80m full wave loop gain versus height (2021)

160m half wave dipole impedance versus height (2020)
160m half wave dipole gain versus height (2020)
80m half wave dipole impedance versus height (2020)
80m half wave dipole gain vs height (2020)

JUMA IC-705 Bluetooth Gateway (2020)
The challenging UNUN Transformer for End Fed Half Wave antenna (2020)

Takeoff angle calculator (Excel file 2020)
OH2AP Autumn Camp presentation (PDF file) (2020)
Simple Foot Switch (2020)
Man Made Noise Filtering (2020)  

Coil Loaded Dipole for 80 meter (2020)
Coil Loaded Dipole for 160 meter (2020)
Square Dipole for 160 meter (2020)  
Z-Dipole for 160 meter (2020)                                    

Common Mode Balun for Antennas (2020)
OH7SV Door-frame loops for 20m, 15 and 10m 2019 (PDF file)
SRAL Summer Camp 2019 in Petäys (PPS presentation in Finnish)
OH7AA Summer day 2019 in Rautalampi (PPS presentation in Finnish)

Practical Ferrite Guide for HF 2018
Ionosonde links near Finland 2018
Circular polarization presentation SRAL Äänekoski 2018 (Video in Finnish)
Coaxial Cable Repair 2018

Useful script for AFEDRI SDR Net users 2018
Antennirakennuskurssi. Antenna building course in Finnish, PPS file 2018
Circular polarization HF antenna with JUMA TC Turnstile Controller 2017

JUMA ASW5 Automatic Antenna Switch 2017
JUMA DFR1 Direction Finder Receiver 2017
External RX port for Kenwood TS-480 2017
GP5 Five Band Vertical Antenna 2016

Remoterig improvement for Kenwood TS-480 PDF file 2016
JUMA HF Tuner Modules 2016
Esitelmä SRAL kesäleirillä 2016 (Presentation in Finnish)
Improved Ferrite Rod Antenna Amplifier PDF file 2015

Enhanced OCF Dipole (Windom) Balun 2014
Measuring Tape Antenna in Flag Pole 2013
Balun Presentation 2013 (pdf file in Finnish)
Electric bicycle charger RFI Modification 2013

Magnetic loop made of copper tube coaxial cable 2013
Magnetic loop for 1.8MHz...7MHz 2013
Magnetic loop presentation in SRAL spring event 2013 (pdf in Finnish)
Dipole impedance 2012

Common mode 1:1 balun for kW power level 2012
JUMA PA1000 Linear Amplifier 2011
JUMA FM70 70 MHz FM Transceiver 2011
JUMA TX136 136 kHz Transmitter 2009

JUMA TX500 500 kHz Transmitter 2009
MOHAIR ONE miniature 3.5 MHz transceiver 2009
JUMA PA100 100 W Linear Amplifier 2008
JUMA TRX2 High performance CW/SSB Transceiver 2007 

JUMA TRX1 DDS controlled CW/DSB Transceiver 2006
JUMA KEYER1 Miniature CW keyer 2006
High performance SSB filter for Direct Conversion RX 2006
Simple CW keyer 2005 

JUMA TX1 DDS controlled CW transmitter 2005
Active ferrite rod antenna for HF 2005
JUMA RX1 Direct Conversion Receiver 2005
Five cent CW key 2005

Twin lead telephone line "killu" RF characteristics 2005
Direct Conversion HF Transceiver with DDS LO 2004
50 ohm to 200 ohm HF wide band low level transformers 2004
Wilkinson splitter for RX measurements 2004

Windom (OCF) baluns 2001/2004
Ferrite rod antenna for 80 meter 2004
Magnetic Loop Antenna for 80 m 2004
Mascot Switched PSU 9320 modification to 8A peak current 2004

150W MOSFET linear amplifier for 80m 1996
Power supply 13.8V 20A schematics (gif) 1996
80 m HF SSB/CW Transceiver 1988
PLL VFO 5.5MHz…6.0MHz for TS130S 1988