I forgot to mention. I do not use the ATU on my K3 on 40m since I have the SteppIR BiggIR vertical, and the K3 SWR reading shows only 1 bar which tells me it is seeing 1:1 SWR which is close to the LPA100 reading of 1.04:1. The LP100 just shows the unvarnished truth sometimes about the actual antenna resonance. It is a great tool.
John K8WDN -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of John Gaynard Sent: Friday, January 02, 2009 2:24 AM To: 'Michael E Fox (N6MEF)'; elecraft@mailman.qth.net Subject: RE: [Elecraft] k3 SWR readings seem generous Isn't the LP100A giving you the actual SWR, not the tuned SWR since the LP100A is getting current samples from the feedline to the antenna and is independent of the K3 tuner. The K3 tuner is making the K3 see 50 ohms. The LP100 is telling you the actual SWR that exists prior to the K3 tuning it to the 50 ohm. I have the LP100 using it with a SteppIR BiggIR vertical and also a Gap Voyager vertical for 160m and 80m. The LP100 reads around 1.04:1 on the SteppIR on 40m as does the K3 (shows 1 bar), which is close to what my old Diamond meter use to read. However, the Gap SWR is around the 2.3:1 range when the K3 (or PW-1 tuner) reads about 1.5:1 or less. I then realized it was showing me the real SWR, not the tuned SWR. I think I am correct in this assumption. John K8WDN -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Michael E Fox (N6MEF) Sent: Friday, January 02, 2009 1:18 AM To: elecraft@mailman.qth.net Subject: RE: [Elecraft] k3 SWR readings seem generous I noticed the same thing. My factory-assembled K3 is reading 1.0 SWR while my LP-100A and tuner both agree on about 1.4-1.5. Michael - N6MEF ------------------------------ Message: 45 Date: Thu, 1 Jan 2009 17:47:04 -0800 From: "Mike Scott" <m...@paxsen.com> Subject: [Elecraft] k3 SWR readings seem generous To: <Elecraft@mailman.qth.net> Message-ID: <7a956b0039b848bd89a04d31855c4...@dbqj5v71> Content-Type: text/plain; charset="us-ascii" I have been working on antennas today and have a puzzle. I am finding that the K3 SWR indications are unbelievable generous. With my 40M inverted V fed with RG8X (50 ohm) coax I see that the K3 seems generous in the SWR indication on tune with ATU bypassed. I have noticed a slight change in SWR with K3 power setting so the following was taken with K3 tune power set to 100 watts. If I set it to 10 watts the discrepancy is greater... SWR SWR SWR Freq. K3 VA1 Daiwa 7.00 MHz 1.3 1.92 2.0 7.05 MHz 1.2 1.92 1.9 7.1 MHz 1.2 1.98 1.95 7.15 MHz 1.3 2.26 2.1 7.2 MHz 1.9 2.60 2.3 7.25 MHz 1.5 2.88 2.6 7.3 MHz 1.6 3.32 2.7 The Daiwa is the CN-101L cross needle meter. The VA1 is the Autek Rx Vector antenna analyzer. The VA1 does not have a tuned input so it is possible that it can be fooled by local broadcast stations. I don't suspect this issue here as there aren't any close by broadcast stations that I am aware of. The Daiwa and the VA1 tend to agree pretty well anyway. The K3 measurements are the outliers. This antenna on a "Tenna Dipper" shows minimal SWR at 7.040 MHz, just where I tuned it a few years ago. The LED does not extinguish indicating higher than 1:1 SWR at the minimum. If you look at the numbers, I guess I don't believe the K3, Do you think my antenna is below 1.6 to 1 across the entire 40M band? So now on to 20M dipole fed with RG58 (50 Ohm Coax)... The Tenna Dipper fully extinguishes at 13.805 MHz indicating that my antenna is bit too long but is close to 1:1 at that frequency. Freq K3 VA1 Daiwa 13.81 -- 1.12 -- 14.0 MHz 1.1 1.24 1.31 14.1 MHz 1.1 1.30 1.70 14.2 MHz 1.1 1.55 1.85 14.3 MHz 1.2 1.69 1.85 RG58 may have some losses on this band so perhaps all of the SWR indications are generous, some more than others. The dipole is a low one and probably isn't 72 ohms at the feed point. Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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
