Today, November 2nd, I successfully tested a homemade 1.2m telescopic antenna on 20m, but spotted my reference incorrectly. I was actually on the Bröhn, DM/NS-122. Please correct.
In the following video you can see and hear 2min of activation with the surprise call from G4AFI. Dear Andrew, thank you for the proof that this little thing works and thanks also to the other good rapports.
One more thing. The empty beer and schnapps bottles that you can see on the video are of course mine. That’s why I made a mistake with the reference, cheers…
again a very interesting and entertaining video, as always.
It seems to me that you are now fully equipped for the Transatlantic event on Saturday.
In times of climate crisis, I’d rather recommend to drink local beer like Lindi or Herri.
You are right, the fifth of the “Kleiner Feigling” must have been bad too, I felt really nauseous afterwards.
As promised, here is the circuit diagram of the antenna.
The number of turns of the coil can be set from 1 to 144 with the two step switches and thus the resonance from 7-30MHz.
The additional ring core (toroid FT 37-43)is used to display the antenna current via LED and is helpful for tuning without an SWR meter.
After some research on this telescopic antenna, like the Elecraft AX1/2 and similar, it turns out for me:
- It’s a dipole antenna (like almost every antenna, hi).
- The radial is one branch of the dipole, the telescopic rod - electrically extended by the coil - the other.
- Firstly, the radial is mainly responsible for the radiation and must therefore run as high as possible.
- Secondly, the radial also essentially determines the resonant frequency through its length and position.
Here are two measurements I took indoors. The radial was 5m and 7.5m long respectively.
The telescopic antenna also made a good impression on 30m. Uwe, DK8OA tested them and got 2 S2S on 30m and euro-wide chasers on 20m.
I can follow your logic regarding the influence of the counterpoise / radial. We have seen various contributions about elevated vs. grounded, one vs. two or three or dozens of radials. Recently, I tried a λ/4 40 m antenna shortened by a loading loading coil in the middle and with the balcony railing as counterpoise. It is impressive what is possible with a rather “undefined” counterpoise. David, DL1DN, has shown this with whip antennas (+ base loading coils) and actually his handheld transceiver and human body as counterpoise.
Please stay curious and continue with your experiments. I enjoy watching your videos. Thanks for sharing!
73 de Peter, DM7KN
My friend Uwe, DK8OA rebuilt my telescopic antenna.
As usual in the olden days in a Willem II brand cigar box. With the serial number II, so to speak.
Today at DM/NS-160 there were the first successful tests. Wilhelm II bravely fought the first part of his spot on the 20m band and reached the Spanish chasers, including Ricardo and Pablo. Comparing the antenna with the 20m long EFHW, it was 1-2S steps weaker as expected.
The qso with a Bulgarian om on the 15m band was very special. But see for yourself in the clip below: