How accurate is the K3 SWR meter
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I am pretty new to the K3 world and just getting acquainted with the
radio. I have a Vectronics Vector 500 antenna tuner with a cross needle swr meter. I notice a disparity between the swr readings on the K3 and on the antenna tuner. So, how accurate is the K3 swr reading? I can imagine that the Vector cross needle reading is not particularly accurate, but I don't know that for fact. I don't have access to a high quality swr bridge, so I'm trying to figure out which reading to trust. Any comments are much appreciated. ...robert -- Robert G. Strickland, PhD, ABPH - KE2WY [hidden email] Syracuse, New York, USA ______________________________________________________________ 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 |
Re: How accurate is the K3 SWR meter
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If the K3's antenna tuner is not set to 'Bypass' then there will almost certainly be a
difference, since the external tuner is reading the SWR between the output of the internal tuner and the antenna, while the K3's reading is between the K3's final amplifier and its tuner. This difference can be very great, because the internal tuner is doing its job! If your K3 does not have an internal tuner or you have set it to Bypass, then there may be a small difference due to inaccuracies in the tuners, and stray inductance and capacity in the K3's output circuitry. You can ignore this -- I would use the K3's reading in this case because it represents what the K3's final amplifier is seeing. On 3/19/2012 6:42 PM, Robert G. Strickland wrote: > I am pretty new to the K3 world and just getting acquainted with the > radio. I have a Vectronics Vector 500 antenna tuner with a cross needle > swr meter. I notice a disparity between the swr readings on the K3 and > on the antenna tuner. So, how accurate is the K3 swr reading? I can > imagine that the Vector cross needle reading is not particularly > accurate, but I don't know that for fact. I don't have access to a high > quality swr bridge, so I'm trying to figure out which reading to trust. > Any comments are much appreciated. > > ...robert -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ ______________________________________________________________ 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 |
Re: How accurate is the K3 SWR meter
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In reply to this post by RobertG
Robert,
I will not answer your question, but may offer some things to contemplate. If I had to make a guess, I would say that the K3 SWR readings should be accurate. Now, while saying that, if you are adjusting for a 1:1 SWR, the exact calibration of the wattmeter will not be any issue, just adjust for minimum reverse power and operate - that will be the correct setting. You have the same problem as the man with two watches and never knows what time it is. I really cannot answer your question because I do not haqve enough data. The measurement of SWR with easy to connect SWR meters is not going to give you great and reliable results. My advice is to trust none of them unless they have been calibrated and proven their worth. If you want to do some tests with 2:1 SWR loads, I suggest you look at the Caddock Thick Film Power resistors. Two 50 ohm resistors in series will give you a precision 100 ohm (SWR = 2.0) dummy load, while 2 of the 50 ohm resistors in parallel will give you a 25 ohm (SWR = 2.0) precision load. Of course, these resistors must be mounted on a heatsink to yield there advertized power rating, but a heat sink salvaged from a computer CPU application will do a great job. This are the loads I use when calibrating the SWR on wattmeters. I cannot project accuracy beyond the SWR=2.0 point, but I do understand my measurement limitations. Good engineering requires that I understand and reveal my measurement limits and the accuracy (1% in this case) of the measurement. 73, Don W3FPR On 3/19/2012 9:42 PM, Robert G. Strickland wrote: > I am pretty new to the K3 world and just getting acquainted with the > radio. I have a Vectronics Vector 500 antenna tuner with a cross needle > swr meter. I notice a disparity between the swr readings on the K3 and > on the antenna tuner. So, how accurate is the K3 swr reading? I can > imagine that the Vector cross needle reading is not particularly > accurate, but I don't know that for fact. I don't have access to a high > quality swr bridge, so I'm trying to figure out which reading to trust. > Any comments are much appreciated. > > ...robert 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 |
Re: How accurate is the K3 SWR meter
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In reply to this post by Vic Rosenthal
If you have an SWR greater than 1:1, there will be standing waves on the
coax between the K3 and the external SWR meter and the length of the coax between the two will change the SWR difference and it will vary with frequency due to the change in wavelength of the piece of coax. If the SWR is 1:1 (try with a dummy load), the two meters should both read 1:1. Try a very short piece of coax or a PL-259 to PL-259 coupler between the radio and the external meter and see if that gets you a closer reading. In any case as stated below it is the SWR at the final amplifier that counts. 73, - Craig, AE6RR -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Vic K2VCO Sent: Monday, March 19, 2012 6:59 PM To: [hidden email] Subject: Re: [Elecraft] How accurate is the K3 SWR meter If the K3's antenna tuner is not set to 'Bypass' then there will almost certainly be a difference, since the external tuner is reading the SWR between the output of the internal tuner and the antenna, while the K3's reading is between the K3's final amplifier and its tuner. This difference can be very great, because the internal tuner is doing its job! If your K3 does not have an internal tuner or you have set it to Bypass, then there may be a small difference due to inaccuracies in the tuners, and stray inductance and capacity in the K3's output circuitry. You can ignore this -- I would use the K3's reading in this case because it represents what the K3's final amplifier is seeing. On 3/19/2012 6:42 PM, Robert G. Strickland wrote: > I am pretty new to the K3 world and just getting acquainted with the > radio. I have a Vectronics Vector 500 antenna tuner with a cross > needle swr meter. I notice a disparity between the swr readings on the > K3 and on the antenna tuner. So, how accurate is the K3 swr reading? I > can imagine that the Vector cross needle reading is not particularly > accurate, but I don't know that for fact. I don't have access to a > high quality swr bridge, so I'm trying to figure out which reading to trust. > Any comments are much appreciated. > > ...robert -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ ______________________________________________________________ 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 ______________________________________________________________ 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 |
Re: How accurate is the K3 SWR meter
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In reply to this post by RobertG
Just a Post Script (or Note) to the discussion:
I was seeing high SWR using my K3 to drive my new 300w HF amplifier, with amp bypassed and QRO tuner (that follows the amp) switched directly to dummy load. This was on 20m. I have the K3 ANT1 (no internal tuner) connected to a MFJ tuner and then thru the 150w Mirage 6m amp and then to the HF amp. DPDT TR relay. The 6m amp bypasses when powered off. Well the solution was removing the 6m amp from the path. Some ham equipment is not well designed for other frequencies it appears! MY SWR went from 1.8 to 1.1 with this simple change. Actual input SWR when driving the HF amp is about 1.4 but the bypass thru the TR relay shows no impedance issues as the 50-ohm dummy is seen by the K3 with no "bump". Since I have a MFJ945E tuner follow the K3, I have two SWR indications to observe and I do often see a difference in indication if the SWR is high. Once the MFJ tunes out any SWR they agree. I have to use a tuner on my triband yagi (very old), but my 80/40m inverted-V is resonant so tuners are not needed. HF amp input matches better at lower freq. bands, though the K3 has no trouble at any band with driving the amp. The Drake MN2000 was added when I installed the new HF amp since it can run up to 2kW. It makes sure the amp sees a good load and also gives me a monitor for the amp output. Summarizing: Check every part of your system from K3 to antenna; you may find some surprises! Always check coax line by line! 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep [hidden email] "Kits made by KL7UW" http://www.kl7uw.com/kits.htm ====================================== ______________________________________________________________ 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 |
Re: How accurate is the K3 SWR meter
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Hi Ed,
I have also high SWR (up to 3:1) on my K3 on 20 mts when the amp is operating. IN the Powermaster it show a 1.5:1. When the amplifier is in Standby the SWR on the K3 was 1.5:1, so something bad when the amplifier is running. I need to do another tests, but your email took my attention. 73, Jorge CX6VM/CW5W K3 #4077 -----Mensaje original----- De: [hidden email] [mailto:[hidden email]] En nombre de Edward R. Cole Enviado el: Martes, 20 de Marzo de 2012 04:16 p.m. Para: [hidden email] Asunto: Re: [Elecraft] How accurate is the K3 SWR meter Just a Post Script (or Note) to the discussion: I was seeing high SWR using my K3 to drive my new 300w HF amplifier, with amp bypassed and QRO tuner (that follows the amp) switched directly to dummy load. This was on 20m. I have the K3 ANT1 (no internal tuner) connected to a MFJ tuner and then thru the 150w Mirage 6m amp and then to the HF amp. DPDT TR relay. The 6m amp bypasses when powered off. Well the solution was removing the 6m amp from the path. Some ham equipment is not well designed for other frequencies it appears! MY SWR went from 1.8 to 1.1 with this simple change. Actual input SWR when driving the HF amp is about 1.4 but the bypass thru the TR relay shows no impedance issues as the 50-ohm dummy is seen by the K3 with no "bump". Since I have a MFJ945E tuner follow the K3, I have two SWR indications to observe and I do often see a difference in indication if the SWR is high. Once the MFJ tunes out any SWR they agree. I have to use a tuner on my triband yagi (very old), but my 80/40m inverted-V is resonant so tuners are not needed. HF amp input matches better at lower freq. bands, though the K3 has no trouble at any band with driving the amp. The Drake MN2000 was added when I installed the new HF amp since it can run up to 2kW. It makes sure the amp sees a good load and also gives me a monitor for the amp output. Summarizing: Check every part of your system from K3 to antenna; you may find some surprises! Always check coax line by line! 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep [hidden email] "Kits made by KL7UW" http://www.kl7uw.com/kits.htm ====================================== ______________________________________________________________ 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 ----- Se certifico que el correo no contiene virus. Comprobada por AVG - www.avg.es Version: 2012.0.1913 / Base de datos de virus: 2114/4882 - Fecha de la version: 20/03/2012 ______________________________________________________________ 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 |
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