SOTA – VK1AD at Isaacs Ridge VK1/AC-041

Saturday 13 March 2021 – working DX SOTA chaser stations in New Zealand and Indonesia, SSB voice mode.

13 March 2021 – VK1AD SOTA activation of Isaacs Ridge. Mt first SOTA QSO with a station in Indonesia, YB1TIA. Map courtesy of SOTA Maps.

Equipment – Yaesu 2m HT, Yaesu FT817ND, 7m telescopic pole, homebrew 40/20m inverted V linked dipole and an experiment with the use of a 10m length of RG-174 coax. I normally carry a 10m length of RG58AU.

Batteries – 8 x Ni-MH LADDA 2.450 Ah AA HR6 batteries

Logging – Lenovo Tab 3 running VK port-a-log

Time	Callsign	Band	Mode	Notes
00:01	VK1FELF	2m	FM	Elizabeth s59 r59 S2S VK1/AC-043
00:02	VK1FDNK	2m	FM	Tony s59 r59 S2S VK1/AC-043
00:03	VK1LH	2m	FM	Les s59 r59 S2S VK1/AC-043
00:05	VK1MCW	2m	FM	Bill s59 r59 S2S VK1/AC-037
00:21	ZL4BDG/P	20m	SSB	s56 r59 S2S ZL1/WL-016 2350 km
00:25	ZL3JD	20m	SSB	Phil s58 r43
00:26	VK5IS	20m	SSB	Ian s58 r57
00:28	ZL1TM	20m	SSB	Andri s58 r55
00:28	ZL1BYZ	20m	SSB	John s59 r55
00:30	VK5PL	20m	SSB	David s35 r53 933 km
00:31	VK5PAS	20m	SSB	Paul s59 r57
00:34	VK6XN	20m	SSB	s58 r51 3088 km
00:36	ZL2IFB	20m	SSB	Gary s58 r56
00:37	VK1LH	20m	SSB	Les s59 r59 S2S VK1/AC-043
00:52	VK3CAT	40m	SSB	Tony s58 r58
00:55	VK5UV	40m	SSB	Rod s58 r56
01:06	ZL3QR	20m	SSB	s58 r55
01:11	VK5AYL	20m	SSB	Sue s58 r51
01:13	YB1TIA	20m	SSB	Tia s58 r35 Indonesia 5453 km at 5 watts SSB
01:14	VK5CZ	20m	SSB	Ian s59 r58 977 km
01:20	VK1MIC/P	2m	FM	Wade s59 r59

FT817ND on 14.320 MHz SSB at 5 watts

Operating position

Homebrew linked dipole 40/20m

Isaacs Ridge

Linked dipole

Edit 10 February 2023. I have updated the inverted V dipole antenna with a 15m link (21MHz). Centre frequencies are 7.090, 14.300 and 21.250 MHz. When both links are closed the antenna is resonant on 7.090 MHz.

End Insulator

20m Link (14MHz)

15m Link (21MHz)

Center insulator

*Post update – If you are wondering? The center insulator is a cut-out section of 6 mm (1/4 inch) kitchen cutting board I purchased from a local supermarket. Drill three small holes on each side and thread the wire through each hole to create small loops. This technique is known as strain-relief. The RF socket is a BNC, 4 hole panel mount.

Note: Assuming a VSWR of 1:1, a 10m length of RG174 at 14 MHz has approximately 0.9dB loss and at 7 MHz 0.6 dB loss. If the power level is 5 watts into the coax, the power out at 14 MHz will be 3.9 watts.

A 10m length of RG58AU at 14 MHz has a loss of approximately 0.5dB. 5 watts in = 4.45 watts out at the antenna feedpoint.

Saving weight in the backpack by substituting RG58x MIL-Spec with RG174 is a compromise and the potential losses should be understood.

Was the experiment with RG174 coax worthwhile, yes it was. 🙂 Will I use RG174 in future SOTA activations? Yes, when I’m hiking 10 km or more and weight saving in the backpack is desirable. 1kg saved in equipment = an extra litre of water I can carry.

Oh, and just to be perfectly clear, I won’t use RG174 for VHF or UHF activations. 🙂

Last Update: 10 February 2023

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