[Elecraft] K3: Strange behavior on 80m

[Rich]

I also noticed this, but on 40m and I think on 20m.  No 80m antenna this 
weekend.  Would not have connected it with the K3 but for your note.

Rich
NU6T

On 11/8/2010 5:34 AM, Luis V. Romero wrote:
> All:
>
> In SS this weekend, I noticed something "new" with my K3:
>
> When attempting to transmit a low power tune signal (I'm set for 10 watts
> out on tune) below, say 3.520, the power out and swr meters begin to
> oscillate wildly.  Going above 3.520, everything looks and works normally.
>
> If I key the transmitter using the TUNE function (press and hold XMIT), then
> sweep the VFO below 3.520, the rig transmits fine at any power level but
> does not receive (see below) until I move the vfo, whereupon it starts the
> oscillation again.
>
> Listening on the receiver, when I tune below 3.517.70, the receiver stops
> hearing anything on the band and what sounds like distorted voice audio from
> a local Broadcaster is heard.  I have a 50kw AM Broadcaster 5 miles away on
> 970kHz, BTW, its their audio that I'm hearing.  Its completely
> unintelligible, but I can correlate that it's the same audio when they stop
> modulation or go to commercials.  Immediately when passing 3.517.70 going up
> in the band, the receiver returns to normal amateur band reception, and the
> distorted audio goes completely away.  I have made a recording in case
> Elecraft wants to hear what this sounds like.
>
> Tested this on SSB and CW, and find that the change to distorted voice audio
> happens at 3.517.70 on cw, 3.519.30 on LSB and 3.516.30 on USB.  This switch
> point appears consistent, as I have repeated it several times.  I don't have
> the NB or NR on, and turning these on don't change the result.
>
> This is with K3 # 3192 using the recalled beta firmware version 4.18.  I
> have not noted this issue before, but to be honest, I don't often use the
> low end of 80m in the course of my normal operation.  I came upon this while
> looking for stations in SS CW this past weekend.
>
> Anybody else seen this behavior?
>
> I don't know if this has anything to do with the issues experienced with
> 4.18, but I thought I would report it to make sure all the information is
> out there.
>
> I too have found that the transmit audio parameters that I normally used
> with 4.14 now sound a bit distorted with 4.18.  I ALWAYS install EVERYTHING
> ( check all the boxes) on a firmware update, not just the portions that have
> changed, as suggested by Eric in his previous email.  I have a direct RS232
> connection from a "real" com port on my computer, through a data switch
> between my MicroKeyer II and said com port that I use to delegate what
> serial connection sees the radio's com port.
>
> I will be backrevving to 4.14 tonight, but kept 4.18 installed for SS CW.
> The new APF, although rather ringy, was extremely useful in grabbing 15m ESP
> QRP signals during SS CW.
>
> I think it's a great first effort by Lyle.  I'm sure further tweaking will
> ensue and as everything in the K3, it will just keep getting better.
>
> -lu-w4lt-
> K3 # 3192
>
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