[Elecraft] What happened to AM mode?

[John [K7SVV]]

The following is the contents of a message that I have sent to the Elecraft 
K3 Support group.
===============================
Since someone else has reported experiencing problems with AM mode with the 
177/158 code on the Elecraft reflector, I would like to tell you what I saw 
after installing 1.75/1.57 (1.77/1.58 has not been installed here yet).  I 
did not hear the " highly distorted audio" that he heard but I did detect a 
small, but very noticeable, amount of clipping on voice peaks while 
listening to the standard broadcast band.  Reducing the AF gain down to 
where the audio could barely be heard did not reduce the amount of clipping 
so it must be happening in an earlier stage.

I can also hear on the stronger stations some heterodyning in both the lower 
and upper sidebands (the K3 was in AM mode).  It isn't loud but it is most 
definitely there and it starts at about 300 to 400 Hz below and above the 
zero beat frequency.  On one local station the heterodyne sounded almost 
like CW.  As the announcer spoke, the heterodyne would be turned off and 
between words it would return.  As I recall , this occurred in the lower 
sideband while the upper sideband had a continuous heterodyne.

The other fellow commented that his VFO A was in the AM broadcast band while 
VFO B was in the 20 meter band.  I really don't understand the conditions 
that caused this but I can say that from time to time after installing new 
F/M code in s/n 148 I have had to manually go through the sequence of bands 
and adjust them so that both VFO's for all bands are indeed in the proper 
band.  This usually manifests itself in the 40 and 60 meter bands, 
Typically the 60 meter band will have a 40 meter frequency in VFO A and a 60 
meter frequency in VFO B.  The opposite will be true in the 40 meter band.

John    [K7SVV]

----- Original Message ----- 
From: "Mike Scott" <mike at paxsen.com>
To: <Elecraft at mailman.qth.net>
Sent: Wednesday, March 19, 2008 4:52 AM
Subject: [Elecraft] What happened to AM mode?


> After uploading new firmware 1.77 and 1.58, AM mode has highly distorted
> audio. I can listen to a strong AM station in sideband mode but AM, no 
> way.
> All I hear is some muffled low frequency audio.
>
> Also as I look at VFO A, I see 0.640 MHz (local AM station) but VFO B 
> shows
> 14.181.23 MHz. I guess this means we can work cross band. I don't remember
> seeing this before.
>
> AM mode used to work but not now.
>
> Mike Scott - AE6WA
> Tarzana, CA (DM04 / near LA)
> K3-100 #508/ KX1  #1311
>