Re: [Elecraft] K3: Now I've heard everything
On Jul 12, 2010, at 7/1210:25 AM, Wes Stewart wrote: > I haven't gotten very far with this because 1) the IMD is apparently > temperature sensitive and drifts, becoming a moving target 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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: Now I've heard everything
> 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 7/12/2010 1:25 PM, Wes Stewart wrote: > Having just acquired an RFSpace SDR-IQ I thought I'd take a look at > the K3's transmit IMD, particularly with respect to input voltage and > output power. > > So I engaged the 2-tone generator, connected a dummy load and > proceeded to take a look at the output spectrum. > > I haven't gotten very far with this because 1) the IMD is apparently > temperature sensitive and drifts, becoming a moving target and 2) I > can hear the two tones acoustically emanating from the PA. The level > is somewhat proportional to RF power and goes away completely when > the power is reduced to the point where the PA drops out. > > Can anyone else confirm or deny that their PA talks back to them? > > Wes N7WS > > > > > > > __ > Elecraft mailing list Home: > http://mailman.qth.net/mailman/listinfo/elecraft Help: > http://mailman.qth.net/mmfaq.htm Post: > mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net Please help support this > email list: http://www.qsl.net/donate.html > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: Now I've heard everything
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 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 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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: Now I've heard everything
On Jul 14, 2010, at 10:31 AM, Wes Stewart wrote: > Chen does your K3 PA talk back? Nothing that I can hear over my tinnitus, Wes. 73 Chen, W7AY __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: Now I've heard everything
Hi Wes, Meant to reply earlier but got distracted. Yes, my PA definitely "sings" with the 2-tone generator on. Like yours it's somewhat dependent on power level. Unlike yours, I can hear mine down to about 2.0w (albeit at a reduced level when the PA drops out.) 73 -- Joe KB8AP On Jul 12, 2010, at 10:25 AM, Wes Stewart wrote: > ...I can hear the two tones acoustically emanating from the PA. The > level is somewhat proportional to RF power and goes away completely > when the power is reduced to the point where the PA drops out. > > Can anyone else confirm or deny that their PA talks back to them? > > Wes N7WS __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3: Now I've heard everything
Hi Joe, One more question, do you have the K3STFNR installed? Wes --- On Wed, 7/14/10, Joe Planisky wrote: Hi Wes, Meant to reply earlier but got distracted. Yes, my PA definitely "sings" with the 2-tone generator on. Like yours it's somewhat dependent on power level. Unlike yours, I can hear mine down to about 2.0w (albeit at a reduced level when the PA drops out.) 73 -- Joe KB8AP __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
