JI1FGX/DU9 Mindanao, Philippines Amateur Radio Diary IOTA OC-130
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Introduction. 【【Lily Diary]
Diary of Life in Mindanao

24/12/11 CVS conversion software for DXCC listings
24/12/05 Aggregation by country from JTDX
24/12/02 ADIF for one month from JTDX
Programs that create files
24/11/24 CwGet and CwType settings
24/11/24 WWDX Contest
24/11/21 CQ Ham Radio
24/11/20 Call Sign Assignment IOTA Number
24/11/13 IOTA 100 Awards Arrival
24/11/12 LoTW WAZ and DXCC
24/11/04 PLDT Optical Internet
24/10/30 Pile-up of 50MHz FT8
24/10/28 Camiguin Is Crowdfunding
24/10/26 50MHz Yagi feeder
24/10/21 RTTY with MMTTY
24/10/19 Firmware for UV-5K
24/10/17 Antenna group seen by drone
24/10/16 7MHz Antenna Pole
24/10/15 3.5MHz zepp transceiver antenna
24/10/14 Hexbeam Purchase Plan
24/10/13 24MHz dipole addition
24/10/13 50MHz Yagi repair completed
50MHz FT8 first pile
24/10/12 Antenna production for 24 MHz
24/10/09 Trouble with Gmail
24/10/09 The Shack
24/10/07 JO1CRA/7 AS-206
24/10/05 3D2V Rotuma Island IOC-060
24/10/01 Camiguin Island Trailer Video
24/09/30 Uruguay
24/09/29 50MHz antenna installation
24/09/25 Pile up on the caller's side
24/09/19 IOTA 100 Award
24/09/18 IOTA Application
24/09/12 DXCC Application
24/09/11 FT8 in communication with KH8T
24/09/08 50MHz Yagi Antenna
24/08/28 Pile up at FT8
24/08/07 Pile up from FT8EU
24/07/19 JW/WE9G in Svalbard
24/06/27 Purchase of air conditioner for wireless room
24/05/28 antenna switch
24/05/27 MFJ-259B Repair
24/05/10 Completed 3-band antenna
24/05/03 7MHz Dipole
24/04/30 7MHz Domestic
24/04/29 Reopening Project
24/04/04 Repair of FTDX3000
24/03/21 To NTC Cagayan
21MHz on a 7MHz dipole (2024/05/03)
It is said that 21MHz, the third harmonic, is carried on a 7MHz full-size dipole
However, if you actually try it, you will need to reduce the SWR by using the radio's internal tuner, etc.
However, it is not a good idea to use Samway's DXV500ZS linear amplifier with an antenna that has a 22.140MHz SWR drop!
I was looking for information on the Internet and found a Youtube channel called "Momo Channel! on Youtube.
https://youtu.be/LbjRYRG9x9I?t=487

It is recommended to put a 4-turn coil 3.5m from the end of the element of a 7MHz dipole.
By extending the element end by 4 turns of element winding, the SWR of 7MHz also drops at the target frequency.

However, when I actually tried it, the center frequency of 21MHz was lowered by setting the coil to 6 turns.

There is no capacitor in this coil, just wind the coil.
Screen capture of NanoVNA's nanovna-severs software
The center frequency that was 22.140MHz is now 21.220MHz and SWR is 1.2
7MHz also has an SWR of 1.7 at 7.100MHz
April 30, 2024   May 10, 2024