From owner-qrp-l@Lehigh.EDU Sat Aug 2 22:18:01 1997 Received: from fidoii.CC.lehigh.EDU (fidoii.CC.lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.8.5/8.8.5) with ESMTP id WAA11562 for ; Sat, 2 Aug 1997 22:18:00 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.Lehigh.EDU with SMTP id <35015-60194>; Sat, 2 Aug 1997 22:17:07 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.Lehigh.EDU with ESMTP id <34934-54564>; Sat, 2 Aug 1997 22:15:17 -0400 Received: from mh004.infi.net (mailhost.infi.net [208.131.167.6]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id WAA28342 for ; Sat, 2 Aug 1997 22:15:07 -0400 Received: from 4708 (pa6dsp3.nr.infi.net [208.128.85.147]) by mh004.infi.net (8.8.5/8.8.5) with ESMTP id WAA21910 for ; Sat, 2 Aug 1997 22:15:04 -0400 (EDT) Message-Id: <199708030215.WAA21910@mh004.infi.net> Date: Sat, 2 Aug 1997 22:14:48 -0400 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 - V MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-To: "qrpforum" X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Gang, I'm testing tuners again. This test was on the Super Tee tuner as described in SPRAT No. 72 and ARCI QQ June '92. Bill Kelsey of Kanga USA sells a kit of parts to build it. Several QRP-L members reported using the Super Tee, and Bill asked me if I would test it. The Super Tee is an unusual design. It is actually an "L" design with seven individually switched inductances and a variable capacitor. It has a 4:1 balun on the input side and matches both balanced and unbalanced lines. The tuner is designed to match impedances of 12.5 ohms and up. I tested the Super Tee in the unbalanced condition first and was disappointed in the results. Bill suggested that I remove the balun and test again. With the balun removed, the tuner was one of the most efficient on the list!! (with the balun removed it would not match less than 50 ohms, of course) Since then, we've been trying to find a more efficient balun. When I tested the balanced condition, there was an entirely different result. The tuner was much more efficient (1 to 3dB better) and even broader range. It matched 160M balanced lines, but not unbalanced! We decided to publish the test results for the tuner as it is, although Bill plans to improve it if he can. It is important to remember that the information below is a summary, and cannot indicate performance on any individual SWR/Frequency combination. Some tuners perform better on certain frequencies than others. 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) Test Results: POWER REQUIRED - Normally, I do not make power tests. The AT-11 tuner requires a certain amount of power to make it cycle, however, so this is of interest to QRPers. The literature indicates .1 watt minimum. However, .1 watt would cycle the tuner only if the antenna load was 50 ohms. Otherwise, up to .7 watt was required to produce an accurate cycle. In some cases, if the tuner was fed less than adequate power, it would give a false reading. (indicate a match of less than 1.5 SWR, when actual SWR was 2.0 or higher) The tuners are normally 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 Murch 2000A 71/72 LDG AT-11 (see notes 1,2) Super Tee 89/126 Note 1: The AT-11 is designed to tune to 1.5 SWR or less. It would often tune to 1.0, 1.3 or something else below 1.5. From a practical standpoint, these SWRs are acceptable. Within it's advertised range, (excluding 160M) there were just 3 combinations tested which did not tune to 1.5 or better. (This is similar to the results obtained with the other tuners tested.) Note 2: LDG spells out the range their tuner will cover clearly, ie., from 6 ohms to 800 ohms impedance. This was an accurate representation. 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 Murch 2000A 35/72 LDG AT-11 30/40 (excluding 160M) Super Tee 9/126 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% Murch 2000A 22% LDG AT-11 14% Note: Match was 1.5:1 or better, not 1.1:1. Super Tee 39% (Bal = 30%, UnBal = 49%) 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 Murch 2000A 22/72 LDG AT-11 36/40 (excluding 160M) Super Tee 67/126 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 Murch 2000A N/A (Murch is an unbalanced only tuner) LDG AT-11 N/A (unbalanced only tuner) Super Tee 63/63 TUNER DESCRIPTIONS: MFJ-949E: A C-L-C "T" design. Uses a tapped air inductor. Rated at 300 watts. Balun provides balanced output. Tunes 160M through 10M. Case about 3-1/2" X 10-1/2" X 7-1/4" ZM-1: A "Z-match" design. Uses a ferrite core inductor. Rated at 15 watts maximum. Link coupled for balanced output. Tunes 80M through 10M. Case about 2-1/2" X 5" X 1-1/2". St. Louis: A C-L-C design. Uses a tapped ferrite core inductor. Rating unknown, probably 25 watts or more. Balun provides balanced output. Tunes 80M through 10M. Case about 2-3/4" X 6-1/4" X 5". Murch UT 2000A: An "Ultimate Transmatch" design popular in the 1980's and found in the 80's Handbooks. (This one did not have the "SPC" mod) Rating 2000 watts. Unbalanced output only. Tunes 80M through 10M. Case about 5-1/2" X 12" X 12". LDG AT-11: An automatic tuner consisting of the "L" design with switched capacitance and inductance. Power rating is 10 watts. Tunes 160M through 10M. Case about 5" X 6-1/4" X 1-1/4". Super Tee: An "L" design with seven switched inductances and a variable capacitor. Includes a 4:1 balun on the input side. Power rating unknown, probably 25-35 watts. Tunes 160M through 10M. Home Brew or kit, but will fit in a small rig sized case. The test methods used were described by Frank Witt, AI1H, in his April, May, 1995 articles in QST, and in the Antenna Compendium V. CUL, Bob Kellogg, AE4IC, Greensboro, NC Prolably, but not nececelery. -- Benny Hill