From owner-qrp-l@Lehigh.EDU Fri Jan 31 22:48:26 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id WAA29490 for ; Fri, 31 Jan 1997 22:48:25 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id WAA29490 for ; Fri, 31 Jan 1997 22:48:25 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35365-23068>; Fri, 31 Jan 1997 22:48:03 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35096-23068>; Fri, 31 Jan 1997 22:46:46 -0500 Received: from mh004.infi.net (mh004.infi.net [198.22.1.119]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id WAA78888 for ; Fri, 31 Jan 1997 22:46:38 -0500 Received: from pa6dsp6.nr.infi.net by mh004.infi.net with SMTP (Infinet-S-3.3) id WAA30330; Fri, 31 Jan 1997 22:47:04 -0500 (EST) Message-Id: <199702010347.WAA30330@mh004.infi.net> Date: Fri, 31 Jan 1997 22:47:04 -0500 (EST) Reply-To: ae4ic@nr.infi.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Bob Kellogg To: "Low Power Amateur Radio Discussion" Subject: Tuner test results II+ Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: ae4ic@nr.infi.net (Unverified) X-Mailer: Windows Eudora Light Version 1.5.2 X-Listprocessor-Version: 8.0 -- ListProcessor(tm) by CREN Status: RO Gang, I'm still testing tuners and more results will follow. In the meantime, I'm adding another criteria that you will find interesting if not amazing. The new data is "Average Loss Percentage". I didn't include this figure before, because I was afraid it would be misleading. (we all know about drowning in a river that averages 1/2" deep) However, one of the problems with tuners is that they may give the user a false sense of confidence. They may do an excellent job of matching the rig to the antenna system, showing SWR 1.0:1, but while they are doing that, they may convert 90% of the signal energy into heat right in the tuner. The same tuner with a different antenna on a different band may lose only 15%, and still match 1.0:1! With our QRP signals, we may not notice heat in the tuner, but our signal strength will suffer. So, the average loss will give us an idea of overall tuner efficiency. It is important to remember that the information below is a summary, and cannot indicate performance on any individual SWR/Frequency combination. Some perform better on certain frequencies than others. It is important to remember also that these results are based on testing one or two tuners which may or may not be representative of all of the tuners of the same model. (particularly true of kits which may have variations in wire routing) The tuners were tested for five conditions: RANGE - The number of SWR/Frequency combinations, within the advertized frequency range of the tuner, that could actually be tuned to 1.1:1 SWR or better. Results: MFJ-949E 137/162 (137 out of 162 possible) ZM-1 140/144 St. Louis 138/144 EFFICIENCY - The number of SWR/Frequency combinations, within the advertized frequency range of the tuner, which resulted in less than 20% (approx. 1 db) power loss. Results: MFJ-949E 49/162 ZM-1 60/144 St. Louis 1/144 (not an error) AVERAGE LOSS PERCENTAGE - The average signal loss of all of the SWR/Frequency combinations which would match to 1.1:1 or better. Results: MFJ-949E 29% ZM-1 22% St. Louis 43% SWR BANDWIDTH - The number of SWR/Frequency combinations, within the advertized frequency range of the tuner, which enabled a tuning range greater than 5% of the primary frequency. (5% on 7.2MHz is 360Kc) (Once the tuner is set, how far can we tune from the frequency before SWR climbs to 1.5?) Results: MFJ-949E 73/162 ZM-1 61/144 St.Louis 77/144 BALANCE - The number of SWR/Frequency combinations, within the advertized frequency range of the tuner, indicating a balanced output with less than 1.5:1 difference between the lines. Results: MFJ-949E 52/81 ZM-1 72/72 St. Louis 72/72 Several other tuners will be tested, including the Rainbow tuner. CUL, Bob Kellogg, AE4IC, Greensboro, NC Prolably, but not nececelery. - Benny Hill