Very low frequencies, 3kHz to 30kHz and extremely low frequencies, 3Hz to 30Hz. I used to spend many hours tuning around VLF. Sferics or spherics, whistlers, strange Earth music… it was fascinating. Now that I have a Mini Whip Active Antenna, I’ve decided to get back into those very, very low frequencies. The VLF converter I’m using is pictured below, sitting atop my Marconi CR100.
The Mini-Whip antenna is very good down to 10kHz and lower but I’m getting quite a lot of break through from strong medium wave stations. The Mini-Whip is on the right in the photo below. If anything, the antenna is too good! One idea I’m contemplating is to put the converter in the shed at the bottom of the garden with a whip aerial on a pole above the shed. Coax from the converter can then be run to the comms receiver in the house. I’ll be experimenting with different aerials once the weather improves.
I’m now using my Alinco DX70 with the VLF converter, pictured below. The input is 100Hz to 100kHz and the output is 4.0 to 4.1 MHz. The Alinco is tuned to 15kHz.