[Elecraft] Heil Pro 7 headset with KX3 - RF feedback?

[Rich]

A couple thoughts and questions:

Are you hearing the "RF?" in the headphones?

If so you may want to increase your MONITOR Level.   I have heard what I 
thought was RF in my headphones.  On the air reports were good audio no 
RF.   I believe the real issue was that a LOW Monitor level setting was 
not enough to drive the headphone speakers.   That is my quess, no 
technical data to back that up. When I increased the MONITOR Level the 
audio in my ears was perfect.

Has anyone told you that there is RF on your TX signal?

I would think RF from a 15watt radio should be easily cured with some 
MIX 31 snap on ferrittes

Rich



On 6/16/2021 23:23 PM, Drew Arnett wrote:
> Hi,
>
> In the KX3 for Field Day department, we plan to use it for the GOTA
> station for phone on HF.  (Yes, will have antennas not on top of each
> other and bandpass filters on ALL radios.)  Would be great to setup
> with a headset and foot switch.
>
> Last weekend, I used my KX3 barefoot on 6 and with a
> transverters-store.com transverter (also barefoot) for 2.  6m antenna
> was 2 elements about 15 ft above the ground and 2m antenna 6 elements
> at 10 feet above the ground.
>
> I worked a couple of contacts on 2m phone with the headset.  Later,
> when I tried to use the headset for phone on 6, seemed like I was
> having a feedback problem.  Cabling was the stock cabling that comes
> with the Heil Pro 7 headset and a footswitch.  Monitor was on and set
> to 4.
>
> So, ALC didn't indicate anything at the normal level (60), and
> increasing it very abruptly caused horrible sounding audio.  (Yes,
> acts like positive feedback.)
>
> I have a small electret mic on a 1/8 plug thing I bought some time ago
> from the computer store.  (Meant at the time for adding mic to
> laptops.)  I have a 1/8" audio extension cable for it.  I plugged that
> in instead of the headset mic and it seemed to act normally.
>
> Is this purely an RF from the TX antenna getting into the mic audio
> problem or is it something else?
>
> Best practice to avoid this problem?
>
> On my todo list:
> - ask here
> - look at KX3 schematic to see if it has RF ingress mitigation on the mic jack
> - ask Heil
> - unplug the Heil mic element and gator clip my cheap electret mic on
> instead and try on 6m in driveway with identical antenna/mast/radio
> setup
> - look for or assemble an RF filter to inline with the mic jack (tough
> to do with this little time
> before field day)
>
> Thanks and best regards,
>
> Drew
> n7da
>
> ps.  Other than this, KX3 was great in the VHF test.  Worked great
> with the transverter on 2 and was a lot of fun running barefoot with
> the sporadic E opening Saturday afternoon & evening.
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