[Elecraft] K2: PSK-31 Power Settings

[Don Wilhelm]

Jon,

That sounds like a classic case of RF where it is not supposed to be - 
in other words, first check for RF feedback - lay out a 33 foot piece of 
wire connected only to the K2 at the near end, and insulated at the far 
end.  If the effects decrease, then look to your antenna system for the 
cure to your 40 meter problems.

OTOH, there was a problem with the KPA100 developing parasitic 
oscillations under certain conditions (like high SWR when using an 
auto-tuner like the KAT100), and that parasitic was most prevalent on 40 
meters.  That problem was addressed by the KPA100UPKIT and is included 
on newer KPA100s.  If your KPA100 has blue toroids at L15 and L16, then 
adding the KPA100UPKIT would be a prudent step.  If you have blue 
toroids at L16 and RFC1, then your KPA100 is up to date, and my 
suspicion about the RF Feedback situation is amplified.

The fact that you can use the procedure for adjusting the output level 
on 20 meters says that the method is valid, but you have some sort of 
other situation present on 40.

73,
Don W3FPR

Jon Perelstein wrote:
> Don,
>
> I'm having trouble with this approach on 40 meters.
>
> I set the power on the K2 to 30 watts and then adjusted
>  the TX volume on the SignaLink as high as I could without getting any ALC reading.  
>
> When I do that, I essentially have zero power output.  There's no deflection on the
>  K2's RF meter and someone who was monitoring my signal said that my signal just dropped off the waterfall.  I have a KAT100 and with these settings the SWR light would not light, indicating that there isn't even enough power out for the KAT100 to measure SWR).
>
> When I increased the SignaLink TX volume to get a 30 watt reading on the K2's RF indicator, I was getting 2-4 bars of ALC. 
>
> On my FT-897, the power display when I'm transmitting PSK is fairly steady.  On the K2 on 40 meters, it was bouncing all over the place, but that may be a function of how the K2 measures RF power out??
>
> I had no trouble using the suggested technique on 20 meters.
>
> Any ideas as to why I'm having problems on 40?
>
> Jon
> KB1QBZ
>
>
>
> I had no problem using this approach on 20 meters, so I'
>
> --- On Wed, 4/28/10, Don Wilhelm <w3fpr at embarqmail.com> wrote:
> I would recommend setting the power to 30 watts.  Then hold DISPLAY to change the metering to ALC - adjust the audio up just to the point where there is no ALC indication (adjust until you see ALC bars and then back off until there are none).  That should give you a cleaner signal and better control of the output level.  Since the gain of the K2 transmit chain varies from band to band, you may have to check the audio drive level again when changing to a different band.  For further explanation, read on.
>
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