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

Thu Jun 17 13:11:28 EDT 2021

These are K9YC’s settings along with a procedure for setting compression level. 
The info is all from discussions on this list. Several years ago, a bunch of people
shared their TX EQ settings. A few were out in left field, but most were very similar
to this.

This is written for the KX3, but the K3 TX EQ is the same.

https://observer.wunderwood.org/2015/09/09/transmit-audio-and-compression-with-the-elecraft-kx3/ <https://observer.wunderwood.org/2015/09/09/transmit-audio-and-compression-with-the-elecraft-kx3/>

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Jun 17, 2021, at 9:55 AM, AL7CR <al7cr at mooseaviation.com> wrote:
> 
> Please list your TXEQ settings.
> 
> On Thu, Jun 17, 2021, at 12:42 AM, Jim Brown wrote:
>> 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.
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>> 
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