KPA1500 TX Sample
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I am trying to get ready for delivery of the KPA1500 and have become
confused about the information available for the TX Sample port. The only information I can find states that this is a low-level signal of -60dBm but dBm is a measure of absolute power which would put this signal at 1 nanowatt. My first thought is that this is a typo and meant to show that the signal level on the port is -60dB with respect to output but need some verification. Is there any information that shows actual transfer function between the output power and the TX sample port voltage into a 50 ohm load? Thanks Dave K5MWR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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David,
It is just a coupler - nothing else makes sense for that use, so your -60dB assumption is correct. Yes, it is relative to the output, so dBm is not the proper designation. 73, Don W3FPR On 3/23/2018 10:09 AM, David Box wrote: > I am trying to get ready for delivery of the KPA1500 and have become > confused about the information available for the TX Sample port. > > The only information I can find states that this is a low-level signal > of -60dBm but dBm is a measure of absolute power which would put this > signal at 1 nanowatt. > > My first thought is that this is a typo and meant to show that the > signal level on the port is -60dB with respect to output but need some > verification. Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Don
Was fairly certain that units were used incorrect but ya' never know so appreciate confirmation. Wanting to get linearity test ready so now I know what is needed to set up. I always want to monitor a new amp and the inclusion of this output allows that. Now I do have one other "assumption" and that is the coupler is before the internal ATU so it is always working with a 50 ohm load, hopefully that is correct. 73 Dave K5MWR On 3/23/2018 10:23 AM, Don Wilhelm wrote: > David, > > It is just a coupler - nothing else makes sense for that use, so your > -60dB assumption is correct. Yes, it is relative to the output, so > dBm is not the proper designation. > > 73, > Don W3FPR > > On 3/23/2018 10:09 AM, David Box wrote: >> I am trying to get ready for delivery of the KPA1500 and have become >> confused about the information available for the TX Sample port. >> >> The only information I can find states that this is a low-level >> signal of -60dBm but dBm is a measure of absolute power which would >> put this signal at 1 nanowatt. >> >> My first thought is that this is a typo and meant to show that the >> signal level on the port is -60dB with respect to output but need >> some verification. > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Dave,
Since that "coupler" has only one output, it is not a full forward and reverse coupler, so it could be nothing more than a toroid output with the wire carrying the full output going through the center of the core - in other words, it can just be an "RF Sampler", and in that case it would not have to be placed in a place where the load is 50 ohms. I think there will be more information to come about its function. For the time being, it is safe to assume it is not a calibrated output, but simply a tap to observe the output waveform, rather than an amplitude measuring device. 73, Don W3FPR On 3/23/2018 2:14 PM, David Box wrote: > Don > > Was fairly certain that units were used incorrect but ya' never know > so appreciate confirmation. > > Wanting to get linearity test ready so now I know what is needed to > set up. I always want to monitor a new amp and the inclusion of this > output allows that. > > Now I do have one other "assumption" and that is the coupler is before > the internal ATU so it is always working with a 50 ohm load, hopefully > that is correct. > > 73 > > Dave K5MWR > > > On 3/23/2018 10:23 AM, Don Wilhelm wrote: >> David, >> >> It is just a coupler - nothing else makes sense for that use, so your >> -60dB assumption is correct. Yes, it is relative to the output, so >> dBm is not the proper designation. >> >> 73, >> Don W3FPR >> >> On 3/23/2018 10:09 AM, David Box wrote: >>> I am trying to get ready for delivery of the KPA1500 and have become >>> confused about the information available for the TX Sample port. >>> >>> The only information I can find states that this is a low-level >>> signal of -60dBm but dBm is a measure of absolute power which would >>> put this signal at 1 nanowatt. >>> >>> My first thought is that this is a typo and meant to show that the >>> signal level on the port is -60dB with respect to output but need >>> some verification. >> >> > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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While all of the info is correct, I also like to mention that an inline station monitor is also a great device. I use a old Kenwood SM-220 as a permenant part of the station. That lets me see the RF amplitude and the linearity of the signal. The trapozoid is used mostly to keep tabs on any hint of distortion. Lots of info on its use.
Mel, K6KBE From: Don Wilhelm <[hidden email]> To: David Box <[hidden email]>; [hidden email] Sent: Friday, March 23, 2018 11:37 AM Subject: Re: [Elecraft] KPA1500 TX Sample Dave, Since that "coupler" has only one output, it is not a full forward and reverse coupler, so it could be nothing more than a toroid output with the wire carrying the full output going through the center of the core - in other words, it can just be an "RF Sampler", and in that case it would not have to be placed in a place where the load is 50 ohms. I think there will be more information to come about its function. For the time being, it is safe to assume it is not a calibrated output, but simply a tap to observe the output waveform, rather than an amplitude measuring device. 73, Don W3FPR On 3/23/2018 2:14 PM, David Box wrote: > Don > > Was fairly certain that units were used incorrect but ya' never know > so appreciate confirmation. > > Wanting to get linearity test ready so now I know what is needed to > set up. I always want to monitor a new amp and the inclusion of this > output allows that. > > Now I do have one other "assumption" and that is the coupler is before > the internal ATU so it is always working with a 50 ohm load, hopefully > that is correct. > > 73 > > Dave K5MWR > > > On 3/23/2018 10:23 AM, Don Wilhelm wrote: >> David, >> >> It is just a coupler - nothing else makes sense for that use, so your >> -60dB assumption is correct. Yes, it is relative to the output, so >> dBm is not the proper designation. >> >> 73, >> Don W3FPR >> >> On 3/23/2018 10:09 AM, David Box wrote: >>> I am trying to get ready for delivery of the KPA1500 and have become >>> confused about the information available for the TX Sample port. >>> >>> The only information I can find states that this is a low-level >>> signal of -60dBm but dBm is a measure of absolute power which would >>> put this signal at 1 nanowatt. >>> >>> My first thought is that this is a typo and meant to show that the >>> signal level on the port is -60dB with respect to output but need >>> some verification. >> >> > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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The P3 TX monitor and SWR/Wattmeter option also does a great job at this. :-)
73, Eric /elecraft.com/ On 3/23/2018 11:55 AM, Mel Farrer via Elecraft wrote: > While all of the info is correct, I also like to mention that an inline station monitor is also a great device. I use a old Kenwood SM-220 as a permenant part of the station. That lets me see the RF amplitude and the linearity of the signal. The trapozoid is used mostly to keep tabs on any hint of distortion. Lots of info on its use. > Mel, K6KBE > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Don Wilhelm
On 3/23/2018 11:33 AM, Don Wilhelm wrote:
> I think there will be more information to come about its function. For > the time being, it is safe to assume it is not a calibrated output, > but simply a tap to observe the output waveform, rather than an > amplitude measuring device. The most obvious use is as a sampling point to feed NR0V's excellent Pure Signal software. Warren received a Technical Excellence award for developing it. The software modifies the driving signal by "pre-distorting" it so that pre-distortion elements cancel distortion within the feedback loop. This is a fairly old technique -- it was, for example, implemented more than 50 years ago in a few professional and consumer power amplifiers, and also within "powered" loudspeakers (that is, those with built-in power amps) using motional feedback from the transducers. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Eric Swartz - WA6HHQ
I use these options and they are superb.
73, Bill K9YEQ -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of Eric Swartz - WA6HHQ, Elecraft Sent: Friday, March 23, 2018 2:12 PM To: Mel Farrer <[hidden email]>; [hidden email]; David Box <[hidden email]>; [hidden email] Subject: Re: [Elecraft] KPA1500 TX Sample The P3 TX monitor and SWR/Wattmeter option also does a great job at this. :-) 73, Eric /elecraft.com/ On 3/23/2018 11:55 AM, Mel Farrer via Elecraft wrote: > While all of the info is correct, I also like to mention that an inline station monitor is also a great device. I use a old Kenwood SM-220 as a permenant part of the station. That lets me see the RF amplitude and the linearity of the signal. The trapozoid is used mostly to keep tabs on any hint of distortion. Lots of info on its use. > Mel, K6KBE > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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