From owner-qrp-l@Lehigh.EDU Wed Aug 20 15:56:14 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 PAA03220 for ; Wed, 20 Aug 1997 15:56:13 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.Lehigh.EDU with SMTP id <35052-22972>; Wed, 20 Aug 1997 15:49:25 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.Lehigh.EDU with ESMTP id <34946-41398>; Wed, 20 Aug 1997 15:47:35 -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 PAA49568 for ; Wed, 20 Aug 1997 15:47:13 -0400 Received: from 4708 (pa6dsp20.nr.infi.net [208.128.85.164]) by mh004.infi.net (8.8.5/8.8.5) with ESMTP id PAA32401 for ; Wed, 20 Aug 1997 15:47:06 -0400 (EDT) Message-Id: <199708201947.PAA32401@mh004.infi.net> Date: Wed, 20 Aug 1997 15:26:18 -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 VI 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, this is the continuing Tuner Test series. Tuners included are:MFJ-949E, ZM-1, St. Louis, Murch 2000A, LDG AT-11, and Super Tee for comparison purposes. The new one is the MFJ-971, a small tuner popular with QRPers. It's in a small case, and has adjustable sensitivity, so it can be made to read power down to 6 watts full scale. (it doesn't have a 6 watt scale, but you can convert mentally to six watts) Literature claims the tuner covers 160M, however, I obtained no matches on 160M. (it could match some condtions which I didn't check, but it would have very limited usefulness on 160M) 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: 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 MFJ-971 113/162 (none on 160 M) 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 MFJ-971 21/162 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%) MFJ-971 31% 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 MFJ-971 87/162 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 MFJ-971 50/81 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) 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. MFJ-971: A C-L-C "T" design. Uses a tapped air inductor. Rated to 300 watts. Balun provides balanced output. Has a switchable sensitivity 300 to 6 watts. Tunes 160M (?) through 10M.. Case about 2-1/2" X 6-1/2" X 6" 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