While making a contact last night with K5W on 40 meters he told me I had RF in my audio. 1: What does that sound like? 2:How do I fix it? 3: Could it just have been a random occurrence at that time? (I have never received that complaint before.)

Icom 7200
LDG AT-100PROII
G5RV

The signal will generally have a raspy, distorted quality to it when RF gets in the audio. Sometimes it's just a ground issue (bad audio cable) but can be worse. High SWR or bad/leaky RF cables/coax can be at fault too. Heck, even "clean" RF getting back into external speaker wires can be the cause depending on how the RF is modulated in the rig.
On another note, low voltage to the rig can cause the transmitted signal to become distorted, sounding like RF on the audio. Older Icoms are finikey about voltage and remember getting reports of this at Field day running an IC-735.
ETA -- Check all your RF and audio connectors for tightness.

What are you mic and processor gains?

Stock mic?

Looked at your ALC while TX?


Oh and PS, curious how my audio was in the net?  N4STG, for anyone that could hear me. ;)

Compression off/Mic Gain 35 ish

Mic is a heil hm-pro - Didn't think of it but it is new to the equation. Only been used on a half dozen or so.

ALC = 5-7 range

Wrap the mic cable through a toroid core and see if that helps.

Your audio sounded good out here in Vegas last night.  There was quite a bit of noise with you, but when you were above that it was clean and intelligible.

Is your radio grounded? If yes, how is it grounded?
I had a similar issue when I purchased a Heil microphone with a Heil cable. I called Heil. They said it was a common problem with some Yaesu and Kenwood radios. They advised to disconnect the cable's shield wire from the grounding pin. I did that and it fixed the problem.
Are you using a Heil cable adapter with a DC blocking capacitor? Most Icoms use condenser microphones and supply DC voltage on the microphone cable to power up the microphone. A dynamic microphone (Heil) does not need this and there should be a DC blocking capacitor installed in series with the microphone cable. A proper Heil adapter should have a DC blocking capacitor installed inside the connector.

It's not a good sign when 500W doesn't make you clear!

Thank you, I played with it tonight some and think I have a happier audio situation now.

Heil mics are prone to this.  Often from RF coming down the coax shield from the antenna, yes, even with
a well balanced antenna such as a dipole.

Put 10-12 ferrite beads on the coax just below the antenna's feedpoint.

OR, put a choke balun there.

Don't freak out when someone say you have RFI on your audio. A lot of times it's just regular signal conditions making it sound funny. Confidence that it is an RFI problem is only assured if multiple people under the same conditions (band, amp, antenna, power level) who have S9 or better copy on you consistently note problems with your audio. The other flare-lit tip-off is an echo of your audio (not a long echo like long path/short path). Echo is a particularly evident on SDRs that have RFI issues because the latency between mic out and ant out is typically 100mS.

That said, chokes, ferrites and high quality grounding and bonding are cheap insurance. Low VSWR, while not an absolute requirement, is also generally helpful.

I only had the RF in my audio when:

(1) Using the amplifier,

(2) Holding the Heil mic (metal body),

(3) My elbow was resting against the metal trim strip along the front edge of the bench
work while transmitting,

(4) Ground strap touching the metal trim strip passing over the edge of the bench, going
down to the floor of the workshop, and out throug a hole to the ground rod.

My elbow completed the circuit, and I would feel a little tingle in my hand and elbow.

Putting a number of ferrite beads on the coax stopped it cold.  Later replaced the ferrites
and centerfed insulator with a 1:1 current balun is the solution on this.  Aside - many 1:1
current baluns are really a series of ferrite beads around the coax encased in a PVC tube.

As a follow up here.

I tinkered with the audio some more tonight using the 857D as the receiving rig and the 7200 as TX.

I was able to turn the mic gain all the way down to 10 and still not affect power levels getting output and the signal got clearer the further down I went...to a point.

I have completely removed all compression.

And then I fired up the SDR dongle and GQRX to check how much bandwidth I am using and I appear to be all neat and pretty at exactly 3kHz wide.  You can even see the audio span when talking if you zoom in enough.

I think I will leave it here and see if I get any comments.