[Elecraft] K3: 6M SSB audio hash

[Don Wilhelm]

Jamie,

Since you did not have a problem with the K2/xvtr with the same setup 
brings up another thought - the K2 required a high level of mic audio 
input while the K3 has plenty of mic gain.
If you have not tried it yet, you may want to reduce the mic gain 
setting on the K3 and increase the gain in your external units.  Using a 
higher level of audio drive to the K3 just might reduce the problem or 
even eliminate it.  If nothing else, it might point the finger at 
something you may not have considered.

I know I am posing more questions rather than providing answers, but 
that is partly how troubleshooting is done.

73,
Don W3FPR

James C. Hall, MD wrote:
> Thanks Don:
>
> I still suspect the 10' cable to the NCS Multi-Switcher is acting like an
> antenna at that high a frequency - however, nothing changed with multiple
> ferrite chokes along this line. Good idea to check the back mic connector,
> although direct attachment of the hand mike and the headset to the front
> connector did not cause the hash. The cable is a very well constructed cable
> made by NCS for the K3 (Kenwood). I can certainly ask NCS (I forgot his
> name, but he's very approachable) regarding the shielding characteristics. I
> use the same cables for the other radios.
>
> You asked if it gets worse with increase in power - yes, but not very much.
> It's nearly an all or nothing deal.
>
> When using my K2/100 with 6M transverter through the W2IHY unit, there is no
> problem at all. The only difference is a longer cable to a different port on
> the multi-switcher to reach the K3 - which is on the other side of my
> monitor/desk.
>
> 73, Jamie
> WB4YDL
>
> -----Original Message-----
> From: Don Wilhelm [mailto:w3fpr at embarqmail.com] 
> Sent: Friday, June 06, 2008 5:17 PM
> To: James C. Hall, MD
> Cc: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] K3: 6M SSB audio hash
>
> Jamie,
>
> The Heil headset will plug directly into the rear panel jacks - why not 
> give that a try as an added piece of evidence that it is not the microphone.
>
> Most likely, something is being picked up on those long microphone 
> cables and is not a K3 problem at all.  Are all the mic cables 
> shielded?  Are all the cable shields connected to the plug/jack shell?  
> They should be.
>
> I have not investigated the W2IHY equipment, but my understanding is 
> that it is setup primarily for pro mics which use balanced AF lines for 
> the mic audio.  My suspicion is that there is something awry with the 
> balanced to unbalanced arrangement when used with unbalanced line 
> microphones such as you have there.
>
> As far as why it shows up only when the PA turns on, I can only 
> speculate there too, but remember that there is more gain in the 
> transmit stages when the PA turns on, and that added gain may make any 
> small AF line pickup more pronounced in your transmit signal.  If it 
> were from RF coupling into the audio, it would vary smoothly from low 
> power to high power and all RF levels in between - you indicated only 
> that it was there with the PA on, but did not say that it got worse as 
> power was increased.
>
> 73,
> Don W3FPR
>
> James C. Hall, MD wrote:
>   
>> Bob:
>>
>>  
>>
>> As a follow up, I doubt it's the Goldline mic/cable itself, as I get the
>> same hash with a Heil headset plugged into the switcher. 
>>
>>  
>>
>> 73, Jamie
>>
>> WB4YDL
>>
>>  
>>
>>
>> From: James C. Hall, MD [mailto:nwtcc at earthlink.net]
>> Sent: Friday, June 6, 2008 04:27 PM
>> To: elecraft at mailman.qth.net
>> Subject: [Elecraft] K3: 6M SSB audio hash
>>
>> Hello: I've noticed some audio hash on my SSB signal on 6M only when the
>>     
> PA
>   
>> relay kicks in at 13 watts. My long microphone cable goes to a
>> Multi-Switcher -> W2IHY Noise Gate/Equalizer -> Heil Goldline microphone.
>> This completely disappears when I use a Kenwood hand mike direct to the
>>     
> K3.
>   
>> Thinking that this was a classic "RF on the line" problem, I clipped on
>> multiple ferrite chokes with many turns on the cable coming from the K3,
>>     
> the
>   
>> Goldline mike, and in between the switcher on noise gate. This didn't even
>> slow it down ! Hmmm. Interestingly when the PA relay is off at 8 watts,
>> there is absolutely no hash. For now, I'll just use the hand mike on 6M
>> (which requires a bit more mike gain) to keep a clean signal. Has anyone
>> else noticed this ? Got a solution ? 73, Jamie WB4YDL
>>   
>>
>>     
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