[Elecraft] K3: Now I've heard everything

[Wes Stewart]

Thanks Joe and Chen,

I'm using a series of power and stepped attenuators to couple the K3 to the SDR-IQ.  The input attenuator is underrated a bit so I've been necessarily limiting transmit time at the higher levels.  When time permits, I'll drag in a directional couple from storage and use it.

Chen does your K3 PA talk back?

Wes

--- On Mon, 7/12/10, Joe Subich, W4TV <lists at subich.com> wrote:

 > Can anyone else confirm or deny that their PA talks back to them?

Does not do it here.  I've made the same tests
 using the SDR-IQ
with the directional coupler from my LP-100 and additional
attenuation for the input to the SDR-IQ.  IMD was stable as long
as the power level was stable (Keep ALC at 5 bars and adjust power
with the power control) and not particularly temperature sensitive
although I did not push long key down times.

I also made measurements of transmit image (+/- 30 KHz) using the
FM filter for transmit in SSB and CW (no measurable image within
the range of the SDR-IQ) using the same test set-up.

The only thing I found necessary was to keep the SDR-IQ and K3
separated (could not leave the SDR-IQ set on the top of the K3)
and use good quality cable between the SDR-IQ and directional
coupler to limit any direct pick-up.

73,

    ... Joe, W4TV



--- On Mon, 7/12/10, Kok Chen <chen at mac.com>
 wrote:

For 
what its worth, when I ran close-spaced IMD measurements (*very* closed 
spaced -- the BPSK31 idle tone :-), I did not notice much drifting in 
IMD values once I got the "ALC" meter up to 4 to 5 bars.  The transmit 
IMD will vary a little (I saw 2 dB) depending on the input drive, even 
while maintaining a constant 5 bars on the "ALC" meter.   But the 
reading was stable as long as I kept the drive stable.

Also, are 
you systematically tapping the signal from the dummy load?  If you are 
just using a short pickup wire on the antenna port of the SQR-IQ, you 
could be seeing other artifacts.  I had used Elecraft's directional 
coupler kit (no one should be without one :-) plus oodles of attenuation
 to directly feed the measurement receiver.

73
Chen, W7AY