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The jumpers must be moved as a pair - both in the 150 ohm or both in the 600 ohm positions or
there will be no audio output.
If you have high-impedance headphones with low audio levels, move the output audio jumpers from
150 ohm to 600 ohm.
If your receiver audio output is low at normal control settings, move the input audio jumpers from
150 ohm to 600 ohm.
If the operators are using headphones with greatly different impedances or the operators have large
differences in hearing sensitivity, experiment with different settings of the jumpers to find the best
balance. It may be easiest to simply have both operators use the same type of headphones.
Ground Jumper H1
The ground jumper is provided to allow control of input and output audio
grounding. The default is for the jumper to be in the INPUT position so the
input audio common circuit is connected to the enclosure. (The enclosure also
has a ground terminal on the back panel for connection to the station ground
system.)
All stations have different configurations of wiring and RF field strengths vary greatly so in some
cases, moving the jumper from the INPUT to the OUTPUT, connecting the headphone common
circuit to the enclosure or removing the jumper entirely may avoid RFI to the audio. The audio
isolation transformers break the direct path for RF between the input and output circuit. No
combination of ground jumper setting will damage the RXSHARE or any connected equipment in
any way - feel free to experiment if you experience RFI in the audio.
Troubleshooting Audio Problems
A sinusoidal 60 Hz (or 50 Hz outside the US and Canada) tone (i.e. "hum") is most likely caused by
a magnetic field from a power transformer or ac wiring. Move audio cables away from the source
of the field and minimize cable lengths to reduce hum.
A sharper "buzz" at 120 Hz (or 100 Hz) is caused by rectified ac power or currents flowing on the
ac neutral of your power wiring. Bonding equipment to a station ground bus or directly from
enclosure to enclosure is most likely to reduce buzz.
Cross-talk between the audio outputs of each radio may be due to the audio common conductor of
the radio-to-RXSHARE cable being broken or too light. Use good-quality shielded cables to avoid
cross-talk. Bonding of the radios to a common ground bus or directly together also reduces cross-
talk.
If RF is being picked up in the headphones, first check that the headphone common conductor is not
broken or compromised. Moving the RXSHARE internal ground jumper from INPUT to OUTPUT
may help. Keep cable lengths to a minimum, as well.
Summary of Contents for DXE-RXSHARE
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