JI1FGX/DU9 Amateur Radio Diary, Mindanao, Philippines, IOTA OC-130.
English. Japanese.



Yesterday's access.
Introduction. [Lily Diary.】
A diary of life in Mindanao.

25/11/20  Satellite tracking Sat Track - Development Version
25/11/19  Kenpro KR-400 arrived by EMS
25/11/18  3.5MHz Antenna Toroidal Core
25/11/16  WiMO V/UHF Cross Yagi
25/11/16  WSJT-X Automatic operation Ver0.1.1
25/11/09  Eyeball with DU9JJY in Cotabato
25/11/04  TNC software for APRSVer1.2
25/11/03  Indonesian satellite IO-86 event
25/10/29  Active Satellite List
25/10/24  FTDX3000 repair completed
25/10/17  Kenpro KR-500 Repair Completed
25/10/15  ARISS SSTV DIPLOMA
25/10/14  International Space Station Information
25/10/13  ST2 interface for driving AC motor rotors
25/10/12  Received APRS signals from ISS
25/10/11  TNC software for APRS manual
25/10/10  TNC software for APRSVer1.0
25/10/09  Making myopia glasses
25/10/09  ICOM IC-820H PLL UNLOCK repair
25/10/05  435MHz Cross Yagi antenna production preparation
25/10/04  Receiving SSTV from the International Space Station
25/10/03  Repair of elevation rotator KR-500
25/10/02  145MHz Cross Yagi antenna production preparation
25/10/01  received APRS signal from ISS
25/09/29  CQ WW RTTY contest
25/09/27  SSTV from the ISS
25/09/26  WARC band fan-out antenna
25/09/25  levation rotator KR-500 acquired
25/09/23 APRS TNC software Dire Wolf with Hamlib
25/09/23 TNC software direwolf
25/09/21  Russian satellite RS-44 beacon
25/09/20 Installing a radio in a car
25/09/17 DH1NGP Peter radio vehicle
25/09/13  3.5MHz SWR increased
25/09/12 3.5MHz Zepp antenna adjustment
25/09/10  Geostationary satellite QO-100
25/09/09  Preparing for the satellite station
25/09/08  DU9JJY satellite station
25/09/07  14MHz late at night
25/09/03  Mitsubishi Strada Pickup Truck
 Oil Change
25/08/18 WSJT-X Automatic operation Ver0.1.0
25/08/18  JTDX Autonomous operation Program Ver0.6.3
25/08/10  Software List
25/07/26 AutoCWType_Ver1.5.8
25/07/20  Create one month's worth of ADIF files from JTDX Ver 2.6.5
25/07/19  Japan's Radio Wave Usage Tax
25/07/13  IARU HF Contest
25/07/10 Software updates
25/07/08 DXV500ZS linear amplifier repair
25/07/07 CQ Machine Program
25/06/21 LoTW system upgrade
25/06/18 RG8 for 3.5MHz arrived
25/06/15  Time setting Ver0.5
25/06/14 Drone Habsan ZINO arrives
25/06/12 Philippine Independence Day
25/06/11 Algeria 7X2RF QSL card.
25/06/10 Translation API Program
25/06/09 DXCC150 award certificate arrived
25/06/08 AutoCWType_Ver1.4.1
25/06/07 Introducing the Shack
25/06/06 A portrait drawn by ChatGPT.
25/05/26 Windows full-width/half-width switching.
25/05/17 OK2ZAW BCD to 16 converter.
25/05/16 For 3.5MHz Zepp antenna.
Stepping motors
25/05/15 3.5MHz stepping motor design.
25/05/14 3.5MHz tuning coil installed.
25/05/11 3.5MHz antenna installation completed.
25/05/03 JTDX Autonomous Driving Program Ver0.4.3.
25/04/26 Drone Habsan ZINO.
25/04/25 Time setting Ver0.3.
25/04/24 AutoCWType_Ver1.3.
25/04/23 Preparing for FTDX3000 LCD repair.
25/04/22 Installation plan for 3.5MHz Zepp antenna.
25/04/21 AutoCWType_Ver1.1.
25/04/20 10,14MHz antenna installation completed.
25/04/19 JTDX Autonomous Driving Program Ver0.4.1.
25/04/19 14MHz antenna pole installed.
25/04/18 ThinkPad X390 repair completed.
25/04/17 Search is now possible.
25/04/15 Preparing the 10MHz dipole.
25/04/12 Hexbeam Part8.
25/04/06 My ThinkPad X390 is broken.
25/04/05. Time setting program.
25/03/31 JTDX Autonomous Driving Program.
25/03/30 Automatic log sending from CWType to Hamlog.
25/03/21 Hexbeam Part 7.
25/03/20 FreeDV Part 3 First QSO.
25/03/18 FreeDV Part 2 QSO in the shack.
25/03/16 Hexbeam Part 6.
25/03/15 Install FreeDV Part1.
25/03/09 Hexbeam Part5.
25/03/07 Hexbeam Part 4.
25/03/05 28MHz antenna modification
25/03/01 FTDX3000 is broken!
25/02/28 Pileup at 50MHz FT8.
25/02/28 DXV500ZS linear amplifier repair.
25/02/27 Tower pipe rebuilding plan.
25/02/26 Direction to Japan from Ozamiz.
25/02/26 28MHz is not available.
25/02/23 DXV500ZS linear amplifier repair.
25/02/22 Hexbeam Part 3
25/02/21 Hexbeam Part 2
25/02/18 28MHz antenna construction.
25/02/17 18,24MHz antenna height construction.
25/02/16 Z26NS Cosovo.
25/02/14 21MHz FT8
25/02/12 7,21MHz antenna repair.
25/02/08 Operating CW at 21MHz.
25/02/05 DXV500ZS linear amplifier failure.
25/01/19 Input Director.
25/01/14 Temporary license renewal.
3.5MHz Antenna Toroidal Core FT240-31 (2025/11/18)
September 13, 2025.

The SWR of the Zepp antenna for 3.5MHz did not drop below 2.
So I wrapped 12 turns of RG58U around one FT240-31 and the SWR dropped nicely.
However, the SWR gradually increases during continuous transmission with FT8.
If you stop transmitting for a few minutes, the SWR drops to around 1,
but when you start transmitting again, the SWR rises again.

When I went outside and touched the ferrite core, it was too hot to touch.
It seems to be causing 'Saturation (magnetic saturation)'

When a large RF current flows through a ferrite core, the magnetic flux density reaches its limit and the permeability drops sharply.
If the temperature rises further, some materials will approach the Curie temperature and lose their magnetism.
In actual operation, this appears as the 'Heat generation reduces the blocking impedance, making the choke ineffective.' phenomenon.

So I bought the FT240-31 on Amazon.
I asked a friend in Japan to forward it to me, and it took two months for the toroidal core to arrive.
I used 3 layers of core and 12 turns of RG58U.
This is the wooden box containing the coil for the 3.5MHz Zepp antenna.
I connected a toroidal core to it.
After transmitting continuously for 30 minutes via FT8, the device becomes too hot to touch.
However, when using one core, the SWR would increase halfway through,
but when I changed to a triple core, the SWR remained stable at 1.5.
However, I encountered a strange phenomenon where the SWR on all bands except 3.5MHz was over 3.
I thought the AMERITRON RCS-10 was broken, so I checked the controller BCD code, but it was normal.
Relay unit installed outside.
Check the BCD code on the terminal block.
Then the lower 2 bits of the signal are not coming.
RCS-10 port number. BCD code. BAND.  
1 000    
2 001    
3 010    
4 011    
5 100 3.5MHz OK
6 101 7, 21, 28MHz NG
7 110 10,14MHz NG
8 111 18,24MHz NG
One of the two control cables was broken.
It looks like it was gnawed by a rat.
 
I connected them with crimp terminals and waterproofed them with liquid tape.
The antennas for each band were switched properly and returned to normal.
 
November 16, 2025.   November 19, 2025.