[Elecraft] Incidental AM using FSK-D

[Joe Subich, W4TV]

 > My K3 increases power by 10% when in Space as opposed to Mark.

Two things here ...  10% is abut 0.4 dB.  How did you measure the power
difference and did you do so with an instrument with enough resolution
to accurately measure that difference at the power level you were using?
For example a Bird Wattmeter can't possibly measure with that level of
accuracy nor is one likely to be able to read an analog meter that
closely.

I have measured my K3 on RTTY with a wattmeter traceable to NIST and
specified for 3% accuracy and have done so at four specific power
levels (25, 55, 80 and 105 Watts) to eliminate any ALC non-linearity
or PA compression from consideration.  The specific Mark/Space power
levels were measured by placing the rig into transmit in FSK_D mode
with the FSK input closed (Mark), measuring the power output for a
given power setting, then opening the FSK input and noting the PO
(and change).

In all cases, the difference between MARK and SPACE was less than 2%
(less than the meter's specified accuracy) and at two power levels (55
and 80 W) the measured difference was less than 0.2W (<0.2 dB at 55W).

These measurements were made with standard "High tones" (2125/2295 Hz)
and the K3 was equipped with the optional 2.8 KHz, 8 pole IF filter.

73,

    ... Joe, W4TV


On 2014-11-10 8:42 PM, Bill Lewis wrote:
> I am looking for information on how to eliminate incidental AM when using
> FSK-D.
>
> My K3 increases power by 10% when in Space as opposed to Mark.
>
> Thanks much, Bill, W8NN
>
>
>
>
> ______________________________________________________________
> 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
> Message delivered to lists at subich.com
>