W6IWI

The call letters W6IWI were first used by Kauko Hallikainen in the 1930s. See the 1938 Amateur Radio Callbook. The 1930s QSL card was similar to that shown above (I may still have one of the originals somewhere). I acquired the call in 2016. Prior to that, I held the call WA6FDN, and prior to that, WN6FDN. The WA6FDN license was probably first granted in 1967 or thereabouts, with WN6FDN a year earlier. However, the earliest record of WA6FDN I can find is the Summer 1969 Callbook .

WN6FDN started with a Heathkit DX-60 transmitter and a National NC-300 receiver running CW on HF. WA6FDN used a Viking Ranger transmitter running AM, CW, and RTTY on HF. RTTY used a Teletype model 15 printer, and a model 14 typing reperf and transmitter distributor. W6IWI now uses an SEA 245 running CW and SSB into an inverted V antenna in Arvada CO. VHF and UHF FM are covered with a Baofeng UV-5R and a Wouxun KG-UV-6X

W6IWI HF Activity

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Power Line Interference Noise

Notes on resolving power line noise have been moved here.

Receiver AGC vs Input

To get an idea of signal strength, data was gathered on AGC voltage (actually AGC count captured from the EIA 485 bus between the radio and the control head) versus receiver input level at the center of each band. A SARK-110 (thanks to Jack, KE0VH for the loan of this excellent instrument) antenna analyzer was used as a signal generator to drive the SEA 245. The raw data is shown here. A plot of the data for 40 meters, as generated by https://mycurvefit.com/ is shown below. This was generated with an auto-smoothed spline fit. It is extended down to the measured noise level on the receiver (AGC count of 10 corresponding to an input level of -118 dBm. From this curve, the 40 meter noise level measured above (AGC = 118.2) corresponds to a receiver input level of about -92 dBm which is 26 dB above the receiver internal noise. S9 is defined as -73 dBm with each S unit being a change of 6 dB. On 40 meters, an input level of -73 dBm gave an AGC count of 184. The power line noise of -92 dBm is 19 dB below -73 dBm or 3 S units below S9. The power line noise is, therefore, about S6.


Based on the data above, a 30 dB increase in the linear region results in an AGC count increase of 98. This indicates we have 0.306 dB/count.

HF Station Details

• HF Transceiver - Seacom SEA 245. This runs 150W CW or SSB between 1.6 MHz and 30 MHz.
• Transmission Line (Transceiver to Antenna Tuner) - 25 feet of RG218XATC 50 ohm coax.
• Antenna Tuner - Seacom SEA 1630. Microntroller-based remote antenna tuner. The microcontroller switches a set of binary weighted inductors and capacitors in and out of a pi network to match the antenna impedance to the impedance of the transmission line to the transceiver (50 ohms). Measures frequency at start of transmission. If frequency used before, tunes to it within 20 milliseconds. If this is a new frequency, it tunes within 5 seconds. A short copper braid connects the tuner to an 8 foot ground rod.
• Antenna Switch - MFJ-4712 - This remote antenna switch selects between the inverted V and the Hy Gain TH-3JRS 3 element 3 band (10, 15, 20m) trapped beam. The antenna switch is put after the antenna tuner so the transceiver is more tolerant of higher SWR from the beam (the beam is somewhat narrow band and tuned for the phone end of the bands). The MFJ-4712 normally uses DC on the coax to switch the relays. However, placing the MFJ-4712 after the tuner would require the tuner pass DC. The tuner would pass DC since it's a pi network with series L and C to ground. However, the tuner also has a transformer across the input to measure the RF voltage (and phase). This would short out any DC on the coax. Therefore, the entire MFJ-4712 antenna switch (control box and RF switch) were located after the antenna tuner. The control box provides a DC block back towards the antenna tuner, and the RF switch provides a DC block towards the antennae (since the beam appears to be a DC short). The MFJ-4712 remote control box is left in the antenna 2 position. The 12VDC power to the control box is switched by a SPST switch in the shack. When that switch is open (no 12VDC to control box), antenna 1 (inverted V) is selected. When the switch is closed, antenna 2 (beam) is selected.
• 3 Element Triband Beam - Details
• Tuner to Balun Transmission Line - About 5 feet of RG218XATC 50 ohm coax. This will typically have a high SWR on it.
• Current Balun - DX Engineering DXE-BAL050H10AT. 50 ohms. 5 kW CW, 10 kW SSB. Located a few feet from the tuner and at the bottom of the mast. On the coax side of the balun, a lightning arrestor with a short copper braid to the 8 foot ground rod.
• Ladder Line, Balun to Antenna - About 27 feet of DX Engineering DXE-LL450-CTL 450 ohm ladder line connects the balun to the antenna. Velocity Factor = 0.91.

  Frequency	Length (wavelengths)
  1.9 MHz	.06
  3.75 MHz	0.1
  5.358 MHz	0.16
  7.150 MHz	0.22
  10.125 MHz	0.31
  14.150 MHz	0.427
  18.118 MHz	0.546
  21.225 MHz	0.640
  24.940 MHz	0.752
  28.850 MHz	0.870

• Mast - About 27 feet (7 sections) of 4 foot fiberglass mast. More sections are available, but it is difficult to erect on my own and probably needs some guying beyond that provided by the antenna.
• Antenna Center Insulator - DX Engineering DXE-UWA-KIT
• Driven Element - 33.33 foot insulated 14AWG wire each side (66.67 feet total) sloping down to about 10 feet above ground on each end. One side goes over the roof of our house. The other side goes through a tree. Not quite balanced, but the best I can do while staying clear of power lines. The 66.67 foot length should be resonant somewhere around 7 MHz. It is non-resonant on other bands, presenting a variable impedance to the antenna tuner.
• Analysis of the 27 foot inverted V

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Fun Stuff

• Jean Sheherd - 1960s DJ at WOR wrote A Christmas Story. Here's the missing scene where he describes being a ham radio operator as a kid. This is from his WOR broadcast in 1965.

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