Fieldday 31-jul-2017

On 31-jul I was in the field, a CG3000 tuner and a wire round around the mast up to the tip. The ground connector of the CG3000 goes to three 10 meter radials. Benefit of this set-up is that you are QRV on all bands from 160 to 10m. The CG3000 can handle up to 200W, the FT-857D produces no more than 100W. Use 10W AM to activate the tuner.

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12,5 meter glass fiber mast
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use the chair for the radio
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CG3000 tuner and three radials
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this is what you need to carry

Last update: 13-aug-2017.

800 Watt 1:4 Balun

The site of DG0SA Wolfgang Wippermann has a large collection of baluns. I replaced the 1:4 guanella balun with the 800 Watt 1:4 balun designed by Wolfgang, goal is to be able use it for higher power. Two ferrite cores are used, the first is a common mode filter to go from unbalanced to balanced for undefined impedance, the second is a 1:2 voltage transformer. I used volcanic wrap tape to isolate the leads between the transformers. As you can see in the images below, PVC tubing of 75 mm is well suited as housing, so this is what you eventually get:

And this is what is inside, the wiring is PTFE AWG18, so teflon coated rugged litze which is somewhat difficult to wind. This was the last view before I glued the cap on the side of the SO239 connector.

And this is a similar view at the other rise, I used plastic and metal rings to keep any water and debris out of the housing. Prefer to leave the cores loose in the tubing, the may generate some heat, once installed it does not move, could be done better but I ran out of ideas here.

And this is what the SWR looks like when I measure it with a 200 Ohm resistor terminated at the end of the balun.

Last update: 2-Jul-2017

New HF antenna

The last month I worked on a new HF antenna, there is no space for anything fancy in our garden, but one thing I could improve is the height of the antenna at the side of the house. For this I installed a mast right of the bathroom window for which I needed to put mounting brackets in the wall. It looks like this and it required me to drill 12 mm holes for 5 expansion bolts for which you need an SDS+ drill (the older drills only go to 10 mm diameter):

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Next is to install the mast, it consists of glass fiber army mast parts that you secure together with aluminum tubes and hose clamps. Four mast parts are put on top of an aluminum part that is clamped in the antenna mounts:

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The new mast
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The antenna is a G5RV junior, I could not fully span it so there is one arm going sideways to the roof of the garage block.
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Looking up under the mast, the matchbox is a 1:4 current balun, the coax-cable goes back over the roof under the roofing tiles to the shack.

What comes out of the antenna is 450 Ohm twin line that goes in the 1:4 guanella balun. For this antenna you need a tuner, and since I didn’t have anything free for this I used the T-match tuner that I built last month.

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The noise floor of this long wire antenna is substantially better than the CG3000 long wire running to the aluminum support mast at the end of the garden.

Tuner settings for this antenna

Freq         L     C1     C2
3603   16,25     +5    -45
3777   10,10   +90    -10
7080     3,50   +45    -20
7130     3,30     +0    -30
7160     3,25     45    -45
14195     1,50   +20    -45
14255     1,50   +20    -45
14310     1,60   +45    -45
14305     1,60   +45    -45
18130     1,50    -45   +45
28300     1,33   +80     +0

So the conclusion is, you can practically use this antenna for 40 to 10 meter, for 80 meter you have to be careful with the inductor, but it can be done, NVIS on 80m was fine up to 200 km away with my set-up. But probably the inductor will dissipate most of the power on the eighty meter band. Another thing is, tuners need to be in a closed case because the capacitors should not spark because of dust etc. What it also proves is that my two ring guanella 1:4 balun does work fine between 3 and 30 MHz for a power up to 100W. For higher powers I probably need to look at a larger ferrite ring.

Last update: 9-jun-2017

Manual antenna tuner

29-4-2017: The antenna tuner is something you can do yourself, variable capacitors, roller inductor and knobs are all used components and they come from the Rosmalen radiomarket. The case is from CONRAD. Unfortunately there is no step counter with the inductor, but it has a stop which you can feel, so just count the left hand turns.

The antenna tuner (also called matchbox or antenna coupler) is a T-shaped network, the inductor does something like 35 microhenry (and probably more), and the capacitors are 30 to 300 pf. I mounted the components on wood because they need to be isolated from the metal case. Straps keep them on the board, and rubber thules are used to isolate the components from the metal case.

Performance-wise this tuner is able to adapt a 200 dummy load to 50 Ohms between 1.8 MHz and 30 MHz, I checked this with my antenna analyzer, it works. There is still space to store a 1:1 or 1:4 balun if needed (see entry on 7-5-2017 how I solved this). I’m not sure how much power the tuner can dissipate, the heat could go in the inductor, or, the capacitors could spark, etc. These capacitors are rated for 1200 Volt, so maybe we can go up to a kilowatt. (hi) (see the entry on 4-5-2017 that discusses where the dissipation could occur in the tuner)

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Added on 4-5-2017, a note:

 

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7-5-2017: Added a 1:1 balun to be able to handle twin-lead lines. Glue, polycarbonate, green tape, some banana jacks and an extra SO-239 case part do the job. The balun is separate from the tuner, you need a patch cable to connect the output of the tuner that goes to the right most SO-239 connector to the left most connector which is the input of the balun. The input of the tuner goes via the middle antenna connector. The balun is nothing more than a common mode filter. The magnetic field lines will stay inside the ferrite core, and any forward magnetic field leaving the tuner will cancel against a returning current that has an opposite magnetic field. This will work fine up to 30 MHz which is the design area for ferrite (it is a 4c65 material), beyond this point you need another trick to design your balun. I added some green tape around the 4c65 core although it is not strictly necessary, on both sides you glue two pieces of polycarbonate and with two parker screws you attach the balun to the aluminum back plate. Check the end result with an antenna analyzer and a multimeter.

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Bill of materials:

  • three SO239 connectors, (relatively easy to get via stores in Rotterdam or Delft)
  • a 300 by 200 by 100 mm aluminum case (difficult to get, consider CONRAD)
  • two banana jacks and the matching case parts (a store in Delft had them)
  • a 4C65 ferrite core, you need it for HF and it shouldn’t saturate below 1 kW (got it from dx-wire in Germany, see also my article on the 1:4 guanella balun)
  • two 30-300pf variable capacitors (got it from a hamradio market)
  • roller inductor (got it from a radio market)
  • wooden ground plate, cut it as required
  • three tules, three knobs (hamradio markets have them)
  • 0.8mm or thicker copper wire (again, the ham radiomarket)
  • 30 cm of 50 Ohm patch cable with two SO239 connectors (I found a store in Rotterdam that I refuse to reveal, it is the only one in town, otherwise, CONRAD or radiomarkets)
  • various M4 nuts and bolts and straps (via any hardware store)

Options to consider: possibly an integrated SWR power meter, this is what I currently solve with a separate AV-CN600 cross-needle meter. The schematics is well known, however, I could not find a cross-needle microamp meter, the electronics is not very difficult, perhaps the calibration is.  Also, many transceivers already have a SWR/Power meter, so perhaps you can skip this step as well.

Last update: 7-May-2017

Chriet Titulaer 1943 – 2017

Op 23-April is Chriet Titulaer overleden. Hij was bekend van televisie uit de jaren 70 en 80 waar hij programma’s zoals de Wonder Wereld presenteerde.  Chriet had een Limburgs accent, en presenteerde het programma geheel in eigen stijl. Ik zat vaak ademloos te luisteren.  Het mooiste aan Chriet Titulaer is dat hij weigerde zijn Limburgse accent aan te passen, ze nemen me maar hoe ik ben, en anders zoeken ze maar een ander. En die vinden ze niet. Inderdaad, die hebben ze nooit gevonden. Chriet was een icoon uit de jaren 80, de Wondere Wereld werd veel bekeken en verschillende voorspellingen zijn uitgekomen. Op een gegeven moment liet zijn gezondheid het niet meer toe op televisie te verschijnen. De laatste paar jaren van zijn leven werd hij verpleegd in een instelling. Chriet, bedankt voor alles wat je achtergelaten hebt.

Last update: 24-April-2017