De-noising the active magnetic receiving antenna.
pa0nhc 20161220 / 20180116
- RF noises which possibly are induced onto the OUTside of the coaxial cable screening, can travel to the antenna unit PCB ground connection. From
there they will, through the INside of the coax cable, run back to the
receiver. And will there be heard.
- For minimal noise hinder, the ground surface of the antenna unit MUST be connected onto
a noise-free grounded mast. This will drain noises, which could be injected to the antenna's PCB-ground surface, directly to the lowZ
grounded mast. The receiver will be grounded to that same mast too, via the screening of the coax cable. The receiver then may NOT be
connected to any (mains-safety) ground.
- If grounding via the antenna mast is impossible, the receiver MUST be
grounded for safety reasons.
- TIP : A low-Z noise-free ground possibly can be made by a connection to the steel reinforcement of concrete structures.
Use THIN (1.6 - 2.8 mm) coax. This can be wound several times loosely through
the big holes in BIG ferrite clamps. Reason :
- 3x though a ferrite hole = 9x more effective than 1x
- Do not worry about cable losses, they are neglect able on these low frequencies. The circuits
of this sebject are designed for low VSWR.
Ferrite material and application.
- For de-noising cables, use ferrite clamps or
ring cores with a high Ui
value, for instance :
Conrad orderNr 1086902, 1086901, 500623 of 1086873).
- Wind thin coax several times LOOSELY through the big hole of the ferrite clamp.
3x though a ferrite hole = 9x more effective than 1x
CHECK for a well closed clamp. Both halves should lay in
flat contact to each other.
- In this newer version, the antenna unit
already contains a ferrite ring mantle current choke. This makes connecting the
coax to the antenna easier.
- Install a ferrite clamp over the coax at the tuning unit.
- Install several ferrite clamps in between, divided over the whole coax cable.
- Burry the coax cable into the soil.
- Install ferrite clamps at the receivers antenna plug and at the receiver-output
of the tuning unit.
- Install a ferrite clamp near the receiver over the mains cable.
- If a separate power supply is used, install near the receiver a ferrite clamp over the DC supply cable.
At your own risk.
ONLY if :
1. The antenna unit is well grounded
2. Your mains power system is equipped with automatic ground leak switches :
You then could disconnect any (mains-safety) ground
at the receivers power