K2 Power Control
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I finally finished my K2 and installed the various accessory pieces. I had two problems both solved with the reapplication of a soldering iron!!! It's a great little radio and I enjoy breaking DX pile ups and rag chewing at the 5 watt level.
I have a question regarding the power control. I can adjust the power in 0.1 w increments per the manual. However for example, if I set the level at 5.0w the resultant output is usually higher. Sometimes by almost a watt. Other times it will be a little lower. I am using the ATU that is calibrated properly. From band to band the same power isn't always the same with no adjustmnet to control. Wonder if RF is getting in the ATU control circuitry or the feedback path from the RF board? Otherwise the radio is a joy to operate. Happy New Year to all, Elliott WA6TLA _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I would only do measurements using a dummy load that presents a
constant to the transmitter output.. Art W6KY Elliott Lawrence <[hidden email]> wrote: I finally finished my K2 and installed the various accessory pieces. I had two problems both solved with the reapplication of a soldering iron!!! It's a great little radio and I enjoy breaking DX pile ups and rag chewing at the 5 watt level. I have a question regarding the power control. I can adjust the power in 0.1 w increments per the manual. However for example, if I set the level at 5.0w the resultant output is usually higher. Sometimes by almost a watt. Other times it will be a little lower. I am using the ATU that is calibrated properly. From band to band the same power isn't always the same with no adjustmnet to control. Wonder if RF is getting in the ATU control circuitry or the feedback path from the RF board? Otherwise the radio is a joy to operate. Happy New Year to all, Elliott WA6TLA _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Elliott Lawrence
Elliott Lawrence wrote:
>I finally finished my K2 and installed the various accessory pieces. I had two problems both solved with the reapplication of a soldering iron!!! It's a great little radio and I enjoy breaking DX pile ups and rag chewing at the 5 watt level. > >I have a question regarding the power control. I can adjust the power in 0.1 w increments per the manual. However for example, if I set the level at 5.0w the resultant output is usually higher. Sometimes by almost a watt. Other times it will be a little lower. I am using the ATU that is calibrated properly. From band to band the same power isn't always the same with no adjustmnet to control. Wonder if RF is getting in the ATU control circuitry or the feedback path from the RF board? > >Otherwise the radio is a joy to operate. > >Happy New Year to all, > >Elliott WA6TLA >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com > > > > resistive load. With a reactive load I would assume that your mileage will vary. Or as said by someone else, accuracy can likely only be assured into a 50 ohm dummy load that is resistive (no complex impedance). bb _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Art - W6KY
Gentlemen and Ladies, Have any of you compared the K2 DSP with a SCAF audio filter ? I have a SCAF and am considering the K2's integrated DSP but really wonder if there, in the end, will be a significant change in my ability to copy weak signal CW signals. Regards, Brian n6iz _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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brian wrote:
> Have any of you compared the K2 DSP with a SCAF audio filter ? I have a > SCAF and am considering the K2's integrated DSP but really wonder if > there, in the end, will be a significant change in my ability to copy > weak signal CW signals. I have the DSP and an OHR SCAF (no longer available). The DSP seems to provide slightly less ringing at narrow bandwidths. It also has the noise reduction, which I find helpful on CW. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by brianboschma
Comparing DSP to SCAF is not easy to do since they are not the same thing.
In SCAF, you're dealing purely with the Analogue signal and varying the BW of the audio signal using switched capacitors. This is effective but lacks noise reduction. DSP on the otherhand will not only give you auto notch and allow you to vary the BW of a received signal, it also provides noise reduction by actively filtering out background noise to its allowable DB level. Unfortunately in doing so, digital artifacts can remain on the signal. In most cases, these artifacts are not very noticeable. Some have complained that DSP does not work well on CW. My personal experience is that the DSP for the K2 does an admirable job and in most instances is not needed with the already excellent filtering available as standard in the K2. SCAF filtering works well in narrowing the BW but does not have Noise Reduction like DSP has. In fact it is not always necessary to narrow the BW of a signal when using DSP. Many occasions Noise Reduction is all that is needed. I have 2 K2 radios and one has the DSP while the other has the SCAF filtering. I'm very pleased with both but the edge goes to my K2 with the DSP filter. Robert VE3RPF ----- Original Message ----- From: "brian" <[hidden email]> To: "Elecraft List" <[hidden email]> Sent: Thursday, December 30, 2004 12:59 PM Subject: [Elecraft] K2 DSP vs SCAF audio filter > > Gentlemen and Ladies, > > Have any of you compared the K2 DSP with a SCAF audio filter ? I have a > SCAF and am considering the K2's integrated DSP but really wonder if > there, in the end, will be a significant change in my ability to copy > weak signal CW signals. > > Regards, > > Brian n6iz > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > > -- > No virus found in this incoming message. > Checked by AVG Anti-Virus. > Version: 7.0.298 / Virus Database: 265.6.6 - Release Date: 12/28/2004 > > -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.298 / Virus Database: 265.6.6 - Release Date: 12/28/2004 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Elliott Lawrence
> Elliott Lawrence wrote:
> > > > >I have a question regarding the power control. I can adjust > the power in 0.1 w increments per the manual. However for > example, if I set the level at 5.0w the resultant output is > usually higher. Sometimes by almost a watt. Other times it > will be a little lower. I am using the ATU that is > calibrated properly. From band to band the same power isn't > always the same with no adjustmnet to control. Wonder if RF > is getting in the ATU control circuitry or the feedback path > from the RF board? > > > Hi, Elliott, The short answer to your questions is... your K2 is just fine. Everything is within limits. The longer answer is... 1. Measuring power is one of the hardest things to do accurately. The venerable Bird wattmeter, which is the de facto amateur radio standard, has an accuracy of +/- 5% of full scale, which means that with a 100 W element in a Bird its reading could be as much as 5 W too high or 5 W too low! Therefore, a question that I have is: since your wattmeter is unlikely to be any more accurate than this (+/- 5%), both it and the "wattmeter" in the K2 seem to be well within limits if they agree to within 1 watt. 2. The next question is... is the K2 or your external wattmeter correct? Without doing a lot of reference measurements, or without using a calorimeter as a power measurement reference, you don't know! You will just have to either decide to believe your wattmeter, especially if it is a Bird-type design, or decide to average the measurements to arrive at a figure. Even using an oscilloscope is unreliable because you won't know the exact impedance of your line or load, which is necessary to calculate power. 3. The next questions is... does the difference you are seeing matter? Well, if you set the K2 to 5 W and you actually read 6 W on the external wattmeter, and assuming that 6 W is the right answer, your K2 is reading less than 0.8 dB low. As power measurements go, this is fantastic accuracy from a simple detector such as is in the K2. This instrumentation error is the predominant error at HF frequencies, the next highest error coming from mismatches in the cables, connectors, and power detector circuitry. Eight-tenths of a dB is a difference far too small to detect on-the-air. 3a. This error varies for different power levels. Thus, you are seeing the K2 readings sometimes high and sometimes low. The error will also change at different frequencies, especially if there is some mismatch in the system. 4. Now, if you are a true QRPer who enters contests and goes for awards and such at the QRP level, then to play fairly you will set the K2 power output so that neither the K2 nor the wattmeter reads more than 5 W. This is a direct result of not knowing which measurement is correct. And in case you are worried about cheating yourself out of every last millliwatt by doing this, see #3 above. The next time you see a power specification in an advertisement, a product review, or a message from one of us on the reflector, remember that it is probably +/- 5% accurate. At best. Sorry for the long message, but this is a subject near and dear to my heart and my line of work. Regards, Al W6LX _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K2 DSP vs SCAF audio filter
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In reply to this post by brianboschma
I am not as descriminating as many on the list and I operate cw almost
exclusively. I have the DSP and know that it works well and is occassionally useful. However, the stock filters in the K2 are so good that I rarely use the DSP filters or de-noiser. SSB may be a different story though. Don K7FJ > > Have any of you compared the K2 DSP with a SCAF audio filter ? I have a > SCAF and am considering the K2's integrated DSP but really wonder if > there, in the end, will be a significant change in my ability to copy weak > signal CW signals. > > Regards, > > Brian n6iz > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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