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

[Jim Brown]

Heil products are wildly overpriced and highly over-rated. No ham needs 
a boom mic headset better than a Yamaha CM500, which sounds great both 
in the headphones and one the air, is very comfortable, costs about $60, 
and has ZERO RFI issues. I'm a Fellow of the Audio Engineering Society, 
have a storage room full of great mics far better than anything Heil 
makes, do very serious contesting. and I've used nothing but the CM500 
for more than ten years. What pro audio folks say about Bose applies 
equally to Heil -- "better sound through marketing."

The CM500 plugs straight into the back of an version of a K3 (and 
probably a K4), and I'll be happy to list TXEQ settings that make it 
sound FAR better than Heil headset mics.

I've been a member of the AES Standards Committee Working Group on 
Microphones for almost 30 years, and I've never met Bob Heil or anyone 
from his company. That should tell you something about how 
"professional" he and his company are. :)  This whole thing about "I did 
sound for XXX rock band is, as my Black friends would say, "a whole 
bunch of shuck and jive."

73, Jim K9YC

On 6/16/2021 8:36 PM, Drew Arnett wrote:
> Shield of mic jack goes to bare metal Elecraft thoughtfully left on
> the chassis metal.  10 nF shunt to ground.  (Need to see where that
> is, but hopefully SMT and with very small loop area.)  Sheet 9:
> https://ftp.elecraft.com/KX3/Manuals%20Downloads/KX3SchematicDiagramDec2012.pdf
> 
> Heil suggests on their tips page generous ferrite choking of all 3
> leads of their Y adapter cable:
> https://heilhamradio.com/support/tips/
> 
> Drew
> n7da
> 
> On Thu, Jun 17, 2021 at 3:23 AM Drew Arnett <arnett.drew at gmail.com> 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.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to jim at audiosystemsgroup.com
>