RF IN MARSHALL MICS

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KB5MD:
I have a Marshall MXL condenser microphone that is very susceptable to rf interference.  It is the microphone and not the audio chain that is picking up the rf and distorting the audio.  I have tried connecting another brand of condenser mic and it works fine.  So, has anyone else had a similar experience with a condenser mic and what, if any, solution was found for the problem?

The Slab Bacon:
I have one and NEVER had any RF problems with mine. Even when sitting 30' below the center of the antenna. Maybe you have a defective mic? ?

ke7trp:
I used to run an MXL mic.  There are two issues common for studio mics.

One, is that the sheild/Ground is floating.  Some cables have Pin 1 hooked to Ground and NOT shield, If you touch the mic while transmitting and you see the RF on scope or hear it through transmitter, Then you can inspect the XLR cable to see if the shield runs to the gear.

The second and most common mistake is that pins 2 and 3 are swapped. There is no standard for XLR mic wiring and it seems that half the gear expects 3 as HOT.  Example, My Blue microphone and my ART voice channel are swapped.  Hooking a standard xlr cable up will work but not in an RF environment.

Recap,  

1. Make sure the Barrel of the connector on BOTH ends is the shield in RF rich applications.

2. make sure of the wiring of Pin 2 and 3.  Look in the manual and see what pin is HOT and look on the microphones manual and see which pin is HOT.  

P.S,  I had to switch my Pin 2 and 3 and when I did that, ALL of the RF issues where gone.

Good luck and hope band conditions improve soon, I miss talking with you guys!

Clark

K5WLF:
When I started doing audio back in the 60s, in lieu of a formal standard, we all used XLR Pin 3 as hot. Sometime in the late 70s/early80s I think, the tide changed and, still lacking a formal standard, folks started using Pin 2 as hot. So, Pin 2 is currently the popular choice for XLR hot. And I still don't know if there's a formal standard or not.

W1DAN:
Folks:

In the 1990s the Audio Engineering Society (AES) formalized pin 2 as being hot for XLR's and balanced analog audio.

On the Marshall mic, sometimes I have to add a ground strap to the XLR at the mic. At one location replacing the mic cable with a higher quality cable (Mogami wire) solved the issue. I think the case might be plastic (??). If so, shielding the case might solve it. This is why I now run a dynamic mic. No RFI.

73,
Dan
W1DAN

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