The Most Common Frequencies

About The Most Common Frequencies

RF = Radio Frequency – above 10 kHz

AF = Audio Frequency – at or below 10 kHz

HF = High Frequency – usually in the 82 kHz range of RF (some use much higher)

LF = Low Frequency – usually in the 571 to 512 range AF

(‘HF” & “LF” used for locating frequencies in this locating discussion only, not to be confused with Broadcast Bands.)

Some locators use the 8 to 10 kHz frequencies of AF. They claim to be LF but actually are in the Mid-range and have some of the advantages and disadvantages of both HF and LF. In the MAC-51B x we chose to give you the option to pick HF, LF, or both, plus magnetics so that you could have the full advantages of them all.

RF or HF Properties
  • RF power restrictions hold down Transmitter power – keeps distance down.
  • HF has a fast signal wave which uses energy fast. Both above are indicators that HF is good for short distances.
  • HF signal is excellent for jumping gaskets & gaps – looses energy doing so.
  • HF can be used in both the Inductive & Conductive Modes.
  • HF in the Inductive Mode is most convenient, as the utility does not have to be exposed to clip onto.
  • HF can be induced into a line via an Inductive Signal Clamp which clamps around an exposed target line to apply the HF signal to a particular line. Can penetrate insulation to avoid clipping on.
LF Properties
  • A slow signal wave which does not dissipate energy as fast as HF, and will not re-radiate a signal as HF does.
  • LF Transmitter can use a higher power to drive signals farther. Both above are indicators the LF is good for long distances.
  • LF signal does not jump gaskets & gaps – can be used to estimate the location of a break in a line.
  • LF can only be used in the Conductive Mode since it does not radiate.
  • LF use requires the Transmitter to be clipped onto (conductive) the target line – so the target line must be exposed & uninsulated … Caution must be used not to clip onto live power lines.
  • LF cannot use an Inductive Signal Clamp because it cannot be induced; it does not jump the gap between the clamp & the target line.
  • LF will stay on the line you put it on & not bleed on to other lines.