From owner-qrp-l@Lehigh.EDU Sat Mar 8 23:36:08 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 XAA22518 for ; Sat, 8 Mar 1997 23:36:07 -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 XAA22518 for ; Sat, 8 Mar 1997 23:36:07 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35485-35050>; Sat, 8 Mar 1997 23:35:37 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35412-22252>; Sat, 8 Mar 1997 23:34:14 -0500 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 XAA35824 for ; Sat, 8 Mar 1997 23:34:09 -0500 Received: from pa8dsp24.nr.infi.net (pa2dsp9.nr.infi.net [208.128.85.57]) by mh004.infi.net (Infinet-S-8.8.5) with SMTP id XAA13508 for ; Sat, 8 Mar 1997 23:35:21 -0500 (EST) Message-Id: <199703090435.XAA13508@mh004.infi.net> Date: Sat, 8 Mar 1997 23:35:21 -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 - LDG AT-11 QRP Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: ae4ic@nr.infi.net X-Mailer: Windows Eudora Light Version 1.5.2 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Hi Gang, The tests on the LDG AT-11 QRP automatic tuner are completed. Unfortunately, because it is an automatic tuner, I had to modify the test methods. This means that the summary below will not compare directly to the previously reported numbers. I've tried to make a statement in each of the usual test areas. The AT-11 was very efficient on the bands tested. In addition, the SWR bandwidth was very wide. In most cases, one tuner setting would cover 1 mHz or more with less than 1.5 SWR. The AT-11 was tested on 80M, 40M, 30M, 20M, and 10M. A noteworthy omission is 160M. (other bands omitted - 17M, 15M and 12M) My tests gave inconsistant results on 160M so I chose to eliminate that band from the test report. Many tuners are inefficient on this band, and had I been able to include 160M data, this tuner would probably have been less efficient. (opinion, not fact) 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) 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) 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. 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) 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) 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". 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