PR781 Heil Mic Issue

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  • Problem
  • Updated 4 years ago
I have a flex 6300. I am using a PR781 Heil Mic, with the Bal Cable. I am getting reports of motor boating audio, almost like computer generated tone. When I use the Flex Mic supplied with the 6300 the motor boating is gone. Any Clues?
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Joseph Rodick

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  • frustrated

Posted 4 years ago

  • 1
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Neal - K3NC, Elmer

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Sounds like RF is coming through the balanced cable, I would put a toroid on it.
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Joseph Rodick

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just added four toroid coils on the balanced cable, till getting the motor boating sound using the PR781
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Burch - K4QXX

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I had this issue the other day with my 6300.  Was using a heil headset with the adapter for the 8 pin mic connection in front of the radio.  Several stations said I had the "motor boating" on my signal.  I turned on the monitor and sure enough, I could hear it.  I unplugged the headset and plugged it back in and it's not done it since.
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Neal - K3NC, Elmer

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Still sounds like you are getting rf in the balanced line (not sure how but if it doesn't happen when coming through the front panel but does through the balanced line, thats all I know it can be!)

73
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Joseph Rodick

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Just ordered another cable from flex.  Thank you for your assistance.


Joseph

WB4SSG

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np2g

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6.1.2 Supported Microphone Types

The FLEX-6000 front microphone connector can support either a dynamic or an electret

microphone. This is an unbalanced high impedance input. The electret bias voltage is not

enabled by default, and must be enabled by SmartSDR.

The DB 15 in the back does not provide a balanced input It provides a Plus audio input and a Frame ground .
(Edited)
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Jon - KF2E

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While adding a toroid to your mic cable may be the answer, people need to understand that all toroids are not created equal. Mix 31 toroids work best for HF frequencies. Mix 43 will work above 10mhz. Unless you are sure of the composition of the toroids you are using, they may not help at all. Almost never are toroids bought at hamfests identified.

Jon...kf2e