[Elecraft] SSB mods

[Dale Boresz]

Hello Paul,

I have done considerable experimentation with the KSB2, to the point of 
purchasing a second one to use as a reference when making adjustments.

I initially installed all of the KI6WX mods detailed in John's excellent 
article "Improving the Performance of the KSB2". To my ears, the 2.5KHz 
mod sounds the best, and is the bandwidth that I prefer.  The microphone 
which I wanted to use was a Heil HM-10 w/ the HC5 element, because it 
had worked so well with my 746PRO. Unfortunately, I have always found 
the output level of the HC5 element to be too low. I found that an old 
ICOM hand microphone, the HM-12 worked very well, and modulated the K2 
very nicely. However, it just didn't sound as nice as the Heil HM5 did 
on the 746PRO, so I still wanted to make the HC5 work.

I built the single transistor mic preamp described here: 
http://www.elecraft.com/Apps/microphone_pre.htm and installed it inside 
the housing of the Heil HM-10, and the results were exceptional. I now 
have *plenty* of drive from the microphone, and it sounds great.

Back to the KI6WX mods. I recently ran into a problem on the 40m band, 
with RF feedback. I fought this one for a long time, with not a whole 
lot of success, and decided to reverse the "KSB2 Increased Gain 
Modification", to see if the reduction in RF gain might help. It did. 
The rf feedback was no longer a problem, and I still have plenty of 
microphone sensitivity. I did leave in place however, the "KSB2 Reduced 
Intermodulation Distortion Modification". Please note, I am *not* at all 
suggesting that the "KSB2 Increased Gain Modification" caused the rf 
feedback problem. However, I'm guessing that in my particular case, 
where I seemed to have other external conditions conducive to rf 
feedback, the extra RF gain was exacerbating the situation. For what 
it's worth, I also discovered that keeping my key plugged into the K2's 
keying jack while using SSB tends to increase the possibility of an rf 
feedback problem.

So, to sum up:
- I did all of the KI6WX mods except for the "KSB2 Increased Gain 
Modification", and opted for the 2.5KHz bandwidth.

- I built the single-transistor mic preamp noted above, and installed it 
inside the microphone housing of the Heil HM-10 microphone.

- The Heil HC5 element now works very well, as does the old ICOM HM-12 
hand microphone, although in my opinion the HC5 is by far the better 
sounding of the two.

I hope this information helps, Paul.

I'd be happy to set up a sked sometime if you'd like to hear what this 
combination sounds like.

73, Dale / WA8SRA


Paul wrote:

>Board members,
>
>Yesterday Bob G3TTV directed me to John KI6WX's website that explains the Un-Official mode.  Another Question - Does this SSB mod work well with the Elecraft Microphones or would it require another style mic?
>
>Has anyone else done this mod could you please offer some additional feed back on this un-official modification?
>
>Thanks
>Paul
>K8QT
>#3479
>
>
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