No audio from 6400 rear MIC port

  • 1
  • Problem
  • Updated 2 months ago
  • Solved
I am running a 6400 with SSDR 3.1.8. I run an inexpensive mic called a BM-800. It requires a 48v phantom power supply between the XLR cable coming from the mic and another XLR cable with a TRS plug on the opposite end. I have the TRS plugged into the MIC port on the back of the radio. I have a separate PTT plugged into the back of the radio as well which does key up the radio.The problem is that I can not produce audio through the MIC. It has worked very successfully before when plugged in to my Maestro but will not work when plugged into the rear of the radio.

The AF Input source is set to MIC.
DAX is OFF
DEXP is OFF
BIAS is ON
+20 DB is ON
Level meter during receive is ENABLED
PTT is not inhibited in TX band settings

I have replaced the phantom power supply, replaced both XLR cables and even tried a second BM-800 mic with the same result. I have performed white button resets along with full power removals, etc. No joy.What am I missing guys?

Thanks in advance for any suggestions.

Norm
K3HMA

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Norman Washburn

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Posted 2 months ago

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Photo of Norman Washburn

Norman Washburn

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Official Response
PROBLEM SOLVED!!!

Thanks for all of the great suggestions. It ended up being that the Maestro takes an UNBALANCED XLR to 3.5 TRS plug and the 6400 radio requires a BALANCED XLR to 3.5 TRS plug. A few minutes with my soldering iron and an old XLR cable fixed the problem.

XLR 1  (Shield) --->   Sleeve
XLR 2 --->   Tip +
XLR 3 ---->   Ring -

Thanks everyone!

Norm
K3HMA