[Elecraft] Elecraft : K2 SSB audio quality

[George W]

Martin.Evans-2 wrote:
> 
> Hello, I've recently started to use my K2/KPA100 on SSB running 100W
> with an MH2 mike mostly on 80m. I use 2:1 compression and mic preamp is
> set to 2. The antenna is an 120ft doublet, 30ft of 300ohm ribbon feeder,
> remote mounted z match tuner right under the centre of the doublet and
> approx 70ft RG58 coax to the rig. I have no RF earth but neither do I
> get much RFI in the house. One end of the antenna is about 10m above the
> operating position and I'm on the ground floor. I've had varying reports
> on the audio quality. Here are a few things I have done/found:
>  
> Every now and then I would get a high current message after which my RF
> peaks (as shown on the K2 bargraph) would drop right down. My remote
> mounted z match tuner uses old broadcast receiver variable caps and I
> think one of them might have been flashing on speech peaks. I have
> backed off the power to 90W and it seems a lot better. The funny thing
> is that when I run at 100W on CW I don't have any probs (ie no high
> current messages). Is there something about the RF peaks on SSB, do they
> overshoot sometimes or is it something to do with rate of rise of the RF
> voltage?
>  
> When I first start an over on SSB the bargraph follows the speech
> waveform and is what I could call "lively" but sometimes it goes very
> sluggish and doesn't seem to be following the audio, is this normal.
> Sometimes the bargraph seems to disappear altogether.
>  
> The antenna and tuner are balanced and I've added a choke balun and
> various ferrites (inc 3 turns on the mic lead and 4 turns on the power
> supply lead) to keep any RF off the rig chassis. I hold the mic about 4
> inches away since I thought I might be overdriving the audio.
>  
>  
> I don't think the audio is bad but perhaps not the best I could get out
> of the K2. Are there any tests/mods/tricks I could try??
> 
> 

Martin,

I run a K2/100 with same mic and settings as you do. I speak right across
the mic face holding the mic right next to my mouth. I get many unsolicited
remarks about  how good the audio is. I am using  double bazooka's on 80 and
40 and a multiband wire antenna on the others. My power setting is 105
watts.  You state that you have no RF earth. I would suggest that you try
grounding the station to get rid of any stray RF that might be coming in
especially on voice peaks. Other than that, the suggestions that Don made
will hopefully cure the problem

73, George, NC5G
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