bhi Ltd
PO Box 318, Burgess Hill, RH15 9NR England.
Tel: +44 (0)1444 870333
info@bhi-ltd.com - www.bhi-ltd.com
bhi GroundBreaker Datasheet
Audio Isolation unit
A simple solution to RFI and ground loop audio breakthrough problems!
Introduction
A simple solution to RFI and ground loop audio breakthrough problems!
RF breakthrough and earth loop current issues tend to happen when a transceiver is in transmit
mode (keyed). You will hear a buzz or your own distorted voice coming out of the audio. The
two main reasons are a poorly matched antenna which results in RF being reflected back into
the radio room or a difference in ground currents between pieces of equipment. RFI issues are
usually caused by reflected waves coming back down the outside of the coax whilst earth loop
problems are usually caused when the same power supply for the radio and “add-on” audio
equipment is being used. The bhi GroundBreaker is a quick and easy solution for this issue as
it isolates the grounds of your external audio equipment from those of the radio system and
prevents ground loops and associated RFI problems from getting into your audio. The bhi
GroundBreaker is easy to install and simply fits in between your radio and audio equipment.
Connections are 3.5mm mono or stereo and no extra leads are usually required.
One of the simplest ways to sort out any earth ground loop and RFI issues with bhi DSP noise
cancelling products is to use a separate DC power supply. This in most cases has the effect of
breaking the earth loop and keeping the stray RFI out. We sell a range of mains plug-in DC
power supplies with world-wide power adapters for most countries that will work with your bhi
DSP noise cancelling product. Please check the accessories page on our website
https://www.bhi-ltd.com/noise-cancelling/power-supplies-and-power-leads/.
bhi GroundBreaker solution
Having tried improving your ground system using ferrites and a separate power supply and you
still have issues then the bhi GroundBreaker is probably the solution to the problem as this
passive in-line audio unit will totally isolate the grounds of bhi DSP noise cancelling product or
other ancillary equipment you are using from those of the radio system, preventing the
unwanted noise from getting into the audio path.
Document: HBA28-80X Issue: 1 Date: 12-01-2018
These small compact in-line audio units come in three different impedances (10 k Ohm, 600
Product Code
Type
Maximum power
GB8M
8 Ohm Mono
500mW
GB600M
600 Ohm Mono
100mW
GB10KM
10 k Ohm Mono
100mW
GB8S
8 Ohm Stereo
500mW/Channel
GB600S
600 Ohm Stereo
100mW/Channel
GB10KS
10 k Ohm Stereo
100mW/Channel
Ohm and 8 Ohm with mono and stereo connections).
Installation
The bhi GroundBreaker is easy to use and simply connects between your radio and audio
DSP/ancillary equipment using 3.5mm connections. The unit works both ways round.
The GroundBreaker can also be used to isolate headphones when plugged into the
headphone socket on the radio.
Balanced to Unbalanced audio systems
Most audio amplifiers used in radios are Class A or AB. They normally have a single ended
(unbalanced) output that works against ground, however, some manufacturers have started
using balanced audio amplifiers and Class D (switch mode) amplifiers. These present a
different problem as most audio ancillary products on the market (unless they are for
professional audio) use unbalanced inputs.
The GroundBreaker can be used to isolate the balanced audio output of the set and allow the
ancillary unbalanced input to be unaffected.
Maximum Power Handling
The GroundBreaker does have limits to its power handling. The 600 Ohm and 10k Ohm
devices are capable of handling the normal audio levels that can be found in most audio
systems. The 8 Ohm units are only meant to be used at powers up to 0.5 Watts input. This
allows interfacing to most bhi DSP audio products and is not meant for the transfer of power into
un-powered speaker units.
Note: Select the relevant GroundBreaker unit above to suit your connection type and
impedance.
Document: HBA28-80X 2
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