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

00:01VK1FELF2mFMElizabeth s59 r59 S2S VK1/AC-043
00:02VK1FDNK2mFMTony s59 r59 S2S VK1/AC-043
00:03VK1LH2mFMLes s59 r59 S2S VK1/AC-043
00:05VK1MCW2mFMBill s59 r59 S2S VK1/AC-037
00:21ZL4BDG/P20mSSBs56 r59 S2S ZL1/WL-016 2350 km
00:25ZL3JD20mSSBPhil s58 r43
00:26VK5IS20mSSBIan s58 r57
00:28ZL1TM20mSSBAndri s58 r55
00:28ZL1BYZ20mSSBJohn s59 r55
00:30VK5PL20mSSBDavid s35 r53 933 km
00:31VK5PAS20mSSBPaul s59 r57
00:34VK6XN20mSSBs58 r51 3088 km
00:36ZL2IFB20mSSBGary s58 r56
00:37VK1LH20mSSBLes s59 r59 S2S VK1/AC-043
00:52VK3CAT40mSSBTony s58 r58
00:55VK5UV40mSSBRod s58 r56
01:06ZL3QR20mSSBs58 r55
01:11VK5AYL20mSSBSue s58 r51
01:13YB1TIA20mSSBTia s58 r35 Indonesia 5453 km at 5 watts SSB
01:14VK5CZ20mSSBIan s59 r58 977 km
01:20VK1MIC/P2mFMWade s59 r59

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.

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


2 thoughts on “SOTA – VK1AD at Isaacs Ridge VK1/AC-041

  1. I love that center insulator. I’ve had good results with RG-174 (at reasonable lengths) over the years. 73, Craig WB3GCK

  2. Brilliant results there, thanks for showing your log. However, I’m surprised with the use of 10m of RG174 as it is extremely lossy in my experience.

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