K2: Excessive ALC on Sideband

[Jon Perelstein]

I've just recently started using phone on my K2/100 (s/n 6550) and I've
noticed that even at an SSbA setting of 1, I'm getting a lot of ALC (3-7
bars when I talk in what I believe to be a normal voice).  I'm using an
Elecraft MH-2 mic.  I checked the wiring for the mic last night and I
believe it is correct.  I also notice that the problem is worse on lower
bands than on higher bands.  I've been operating the radio at about 80
watts on phone.

That's consistent with my experience in digital modes, where I have to turn
the output of my computer down to around 20% and keep the TX control of my
Signalink turned down to around 2/10ths (the 9 o'clock position).  I have
checked the jumper settings in my Signalink to make sure I'm not using the
special jumper for increased gain on Tx.  I operate the radio at 30 watts
on digital modes.

The KSB2 manual says that the value of R15 can be changed to increase the
attenuation on SSbA.  What kind of values should I be thinking of?

Are there any other adjustments I can/should make to improve the situation?
 I caught some comment in a post a few years ago about there being an issue
with the KSB2 on lower bands and mention of their being a fix, but I'm not
sure what to search for in the archives (or rather, the terms I was
searching for didn't give me anything that seemed relevant).

Thanks and 73s
Jon, WB2RYV
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Don Wilhelm-4]

Jon,

It is normal to have more TX RF Gain on 80/40 meters than on the higher
bands.  It is the gain through the transmit stages and will vary with
frequency.  The ALC circuits on the KSB2 board normally handle that
variation.
Make certain you have the normal value for R14 (1k) on your KSB2 board,
and leave R15 at 180 ohms.
You will normally use an SSBA setting of 1 with the MH2 microphone.
Note that there are really only 2 SSBA settings for the KSB2 - 2 and 3
are the same.

There is a mod to increase the KSB2 RF gain, but none to level it out
across the bands.

73,
Don W3FPR


On 3/25/2012 11:09 AM, Jon Perelstein wrote:

> I've just recently started using phone on my K2/100 (s/n 6550) and I've
> noticed that even at an SSbA setting of 1, I'm getting a lot of ALC (3-7
> bars when I talk in what I believe to be a normal voice).  I'm using an
> Elecraft MH-2 mic.  I checked the wiring for the mic last night and I
> believe it is correct.  I also notice that the problem is worse on lower
> bands than on higher bands.  I've been operating the radio at about 80
> watts on phone.
>
> That's consistent with my experience in digital modes, where I have to turn
> the output of my computer down to around 20% and keep the TX control of my
> Signalink turned down to around 2/10ths (the 9 o'clock position).  I have
> checked the jumper settings in my Signalink to make sure I'm not using the
> special jumper for increased gain on Tx.  I operate the radio at 30 watts
> on digital modes.
>
> The KSB2 manual says that the value of R15 can be changed to increase the
> attenuation on SSbA.  What kind of values should I be thinking of?
>
> Are there any other adjustments I can/should make to improve the situation?
>   I caught some comment in a post a few years ago about there being an issue
> with the KSB2 on lower bands and mention of their being a fix, but I'm not
> sure what to search for in the archives (or rather, the terms I was
> searching for didn't give me anything that seemed relevant).
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Jon Perelstein]

As always, thank you Don.  I have confirmed that R14 is correct.  I'll
leave SSBA setting of 1 with the MH2.

73s
Jon, WB2RYV
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html