SDRplay Community Forum

BUILDING A STABLE 1:1 LOW CAPACITANCE TRANSFORMER - 1

The low capacitance transformer needs a stable configuration. I decided to build a suitable housing which keeps input & output common terminals insulated from each other. Here below the building sequence. I used a thick walled PVC pipe.

@glovisol
The discone itself NEVER will receice any reasonable signal at low frequencies! It is much to small compared to the wavelength.

Thanks a lot for making it clear, I was totally confused and puzzled.

Now it makes perfect sense.

... to a HI Z 1 Kohm input with no matching? Please look at the posted photos (even those posted before): I have always connected and tested the Discone antenna (50 Ohm) connected to the 50 Ohm coaxial input of the RSPduo using a 50 to 50 Ohm (1:1) toroid transformer. Up to now I have NEVER connected ...

Did you try to transform the 50 Ohm Discone antenna to a higher impedance? The Hi-Z isn't 50 Ohm but 1000 Ohm, the voltage/amp levels going into the Hi-Z should be more suitable for it. I do not know what the impedance is outside it's design ...

Thank you both. An excellent experiment.

I have removed the electrical ground and found no difference, so the bottom line is that the Discone antenna, plus the support pole, plus the 20 m coax cable "float" with no ground connection at all and provide the already described performance. The 20 m band opened up ...

Some time ago I did run some tests and simulations on the antenna at low frequencies. Here you find a comprehensive presentation of the basics. It may help to answer some of the questions. At my installation (l = 15m) the antenna gives good results up to a frequnecy of a wavelength of 4l=60m or f=5M...

Hi Glovisol, Yes it seemed to me that the electrical earth may be acting as an antenna for things other than interesting radio signals. I have seen noise carried by mains wiring cause significant noise on HF. Normal noise reduction techniques using ferrite cores applied to the wiring brought a great...

... (but I might have misunderstood....) and stated by others, especially ON5HB, has brought this matter to utter confusion....If I cannot connect the Discone directly with a 50 Ohm cable because of noise and if I cannot use an RF choke to insulate common mode and furthermore if I cannot insulate and ...