[Elecraft] K2: Attempting K2 SSB modulation and ALC mods, but board too old?

[Andreas Hofmann]

Don (and others),

One problem down, one to go.

I believe I have solved the modulation issue.  I started fresh and did all alignments, from Freq calibration, PLL, Filters, BFO passband (with your excellent descriptions on how to use Spectrogram).  Especially the BFO was way off. I am not sure if these settings somehow deteriorate overtime or what happened.  I know that stored digital values cannot simply change, but analog components can and maybe that's what it is. Or (not impossibly) I screwed up big times 9 years ago when I built the K2.  I listened in a SDR and really noticed how the BFO passband changes the overall modulation.  Great.

Now, my SSB power output is still not very good.  I would think that this is an ALC issue.  On the same frequency on 40m, using a dummy load, I can get 110 W out in CW, but about 40 W in SSB (and me screaming into the mike), with ALC showing four LEDs on the right display. On 20m, I get about 40 W out without an ALC.  This is with both the Elecraft MH2 and the Elecraft Heil pro 2.

So, I think I am kind of back to my original issue of trying to attempt the QRP Projekt mods for more mike drive and ALC circuits.  Or are there other things I should be checking first?  Is there a way to temporarily "disable" the ALC to see if the output is artificially controlled down?

Thanks,
Andy, KU7T




-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don Wilhelm
Sent: Saturday, September 29, 2012 5:25 AM
To: Elecraft at mailman.qth.net
Cc: Andreas Hofmann
Subject: Re: [Elecraft] K2: Attempting K2 SSB modulation and ALC mods, but board too old?

Andy,

Does your SSB OP1 filter look good on the Spectrogram display?
You must select the OP1 filter for the SSB FL1 filter position.
SSB FL1 is the filter used for SSB transmit - there is no choice, and you must adjust the BFOs for good response - filter passband low frequency corner at 300 Hz and the high frequency corner at 2600 Hz.

73,
Don W3FPR


Thanks for the prompt reply.

  I have made both the mods you mentioned below (filer bandwidth and A2B).  In CW the K2 functions flawlessly, I get out more than 100W out on most bands.

  I am using the MH2 or Heil Pro set and just get horrible audio reports and the ALC does not play well.  On 40, the ALC comes on with 4 LEDs, but without reaching 100W; on other bands ALC never lights any LEDs.  It may be possibly that the SSB board is just misaligned.  It was my understanding that the filters for SSB are only used in receive, but in transmit the same filter as in CW is used, so alignment may not be the problem.

Should I start with redoing all alignment steps for the SSB board?

Thanks Andy, KU7T
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

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