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I use 75 ohm, foam filled, all copper satellite TV coax, with braid and foil for my active antennas.

Low loss and effective screening, don't worry about the slight impedance mismatch to 50 ohms.

Something like WF100 costs around £30 for 50m.

Don't use stuff with air spacing, or aluminium foil, or copper clad steel.

Regards,

Martin

They are most likely pirates, probably fishermen.

They often like to find "private" frequencies in order to conduct their "private" conversations, and these tend to be on frequencies with number sequences that are easily remembered.

There tend to be lots of them speaking all sorts of Asian languages, and frequently performing lots of chanting.

5 to 12MHz seems to be the most used frequency ranges, but they can pop up almost anywhere.

Regards,

Martin

As I said previously, the majority of Bias Tees have very poor filtering between the DC line and the RF path.

Nearly all the circuits you find on the internet tend to be outlining theoretical designs, that concentrate on providing the least attenuation and impedance "bumps" in the direct RF path, but don't worry about what happens with RF entering via the DC path.

The better designs for our reception purposes, incorporate additional filtering components in the DC path, in order to reduce this problem. But very large values of L and C are required in order to be effective at the low frequencies, especially at less than 100kHz.

Regards,

Martin

Check the antenna Bias Tee first.

Many don't have enough filtering built into them.

Regards,

Martin

Before swapping supplies, make sure that it is the Apple power brick that is causing the problem. It may well be something else.

The signal will most likely change its characteristics if the power supply load is altered in some way.

Try a different make of supply and see if the interference on that frequency changes or goes away completely.

Regards,

Martin