



[1] Transmission
Line Transformers Handbook. Jerry Sevick, W2FMI, Amidon
Associates Inc. 1997. [2] Building and Using Baluns and Ununs. Practical Designs for the Experimenter" (2nd printing 1995) Jerry Sevick, W2FMI, CQ Communications 1994, ISBN 0943016096. [3] Transmission Line Transformers (4th edition 2001) Jerry Sevick, W2FMI, Noble publ., ISBN 1884932185. Jerry Sevick W2FMI, balun articles in Communications Quarterly: [4a] "Baluns Revisited", Summer (July) 1992, p1318. [4b] "The 4:1 Balun", Fall (Oct) 1992, p2329. [4c] "6:1 and 9:1 Baluns", Winter (Jan) 1993, p43 51. [4d] "1.5:1 and 2:1 Baluns", Spring (April) 1993, p3944. [4e] "The 12:1 Balun", Summer (July) 1993 p3638. [9] "Automatic Tuning of Antennae". M J Underhill [G3LHZ] and P A Lewis. SERT Journal, Vol 8, Sept 1974, p183184. Reprint of paper in Mullard Research Labs Annual Review, 1973. Introduces the idea of using phase, resistance, and conductance for unambiguous adjustment of the matching network in automatic antenna tuning systems. Describes the matching process using Zplane diagrams, and operations involving lines of constant resistance and circles of constant conductance. Advocates the use of a πnetwork with one or other of the capacitors set as near as possible to zero capacitance (i.e., using the πnetwork as an Lnetwork, but without the need for switching), on the basis of minimised voltages and lowpass filtering. Notes that the input impedance of a 'typical' antenna operating between 1.5 and 30MHz can have a resistive component between 3 and 2000Ω, and a reactive component between 2500 and +500Ω. Gives criteria for achieving 1.2:1 SWR, i.e., 45 ≤ R ≤ 56Ω, 17.5 ≤ G ≤ 22.5 mS, 7° ≤ &phu; ≤ +7°. [10] "Antenna Tuner With a New Twist", Bob Baird W7CSD, Ham Radio June 1990, p59 & 61. Uses tapped coil and interpolation capacitor. Unusual use of LCL Tnetwork configuration with mutual inductance between the coils. [11] The metal enclosure of a matching network forms a shorted turn around the inductor. Hence the eddy current losses in the case appear as a resistive component in the impedance of the coil. Lowest losses are incurred by using a large box, or failing that, a box made from material having high RF conductivity. Ferromagnetic materials having high resistivity (such as steel) are unsuitable. Silverplated brass or plain copper may be too expensive for commercial designs, but aluminium is affordable and acceptable. Resistance at the joints between chassis and removable cover should be kept to a minimum by securing bare metal to bare metal at all overlap points, using plenty of screws. [12] It is sometimes argued that since the (unloaded) Q of a roller inductor increases as the inductance is increased, it is best to use the largest possible inductance. This is true when the inductance is in parallel with the the signal path, but not when it is in series. The unloaded Q of the coil does not dictate the efficiency of the system. What matters in this case is the series resistance, and this increases as the length of the conduction path through the inductor is increased. [13] "Clean Up Your Signals with BandPass Filters" Ed Wetherhold W3NQN, QST May 1998 p4448, June 1998 p3942. Threeresonator bandpass filters for 160, 80, 40, 20, 15, and 10m, using Micrometals (same as Amidon) powderediron and phenolic toroidal cores and highvoltage NPO ceramic capacitors (200W throughput, 50Ω termination). Design information and return loss measurements. Filters prevent radiation of spurious signals, and prevent receiver blocking and damage due to strong outofband signals (i.e., for multiple HF transceivers and antenna systems operating on the same site). [14] "A GeneralPurpose Antenna Matching Unit", M J Grierson, G3TSO. Rad Com, Jan 1987, p1822. Reprinted in "HF Antenna Collection" Ed. David Erwin G4LQI, RSGB publ 1991 ISBN 1872309089. p119124. Constructional article describing Tmatch tuner with integral SWR meter and outputside balun. Author considers SPC and differential capacitor configurations but rejects them on grounds that harmonic suppression is provided by modern TX. Balun is voltage type 1:1  4:1 switched, with powdered iron toroidal core [for preference, see refs 1  4]. Suggested tuning procedure involves beginning with both capacitors set halfway. Observes "it is not uncommon ... for one capacitor to be very sharp ... while the other is flat and unresponsive". [15] "Understanding the Ttuner (CLC) Transmatch" William E Sabin, W0IYH, QEX, Dec. 1997, p1321. Suggests that shorting out C1 and C2 will improve efficiency in some situations. States [incorrectly] that efficiency increases as L is reduced. [16] "Save Your Tuner for Two Pence", Tony Preedy, G3LNP, Rad Com, May 2000, p2025. The "two pence" in question are copper cams used to make shorting switches for the capacitors in a commercial Tmatch tuner [note that defacing coins is illegal in many countries]. Article contains much useful information on ATU design and coil losses, with graphs of Q vs frequency for various roller inductors [unfortunately, working out which graph corresponds to which coil is left as a puzzle for the reader, but the solution appears to be a=1, b=2, e=5. If this is correct, graph e is for the inductor from an MFJ 989C tuner, and shows a Q of about 100 at 4MHz, and about 40 at 29MHz]. Author demonstrates that lowest losses occur in the Tmatch when one capacitor is set to its maximum value, and consequently gives correct procedure for adjustment. Goes on to describe shortingswitch modification, noting that in addition to reducing losses, it permits higher power on higher frequencies, and extends the upper frequency tuning limit for a given range of load impedances. In practice, notes that there is sometimes insufficient capacitance (in the commercial tuners modified) to effect a match with the Lconfiguration at lower frequencies, and the intermediate transformation (Tnetwork) is required. [17] "The EZ Tuner", James C Garland W8ZR, QST Apr 2002 p4043. May 2002 p2834, Jun 2002 p3336. Reduces the number of coil tappings required for a Tnetwork tuner on the basis of constant SWR curves and power loss curves [but considers only resistive loads in the design procedure]. [18] MFJ986 DifferentialT™ Antenna Tuner. Advertisement 2001. www.mfjenterprises.com . "Replacing two variable capacitors with a single differential capacitor gives a widerange Tnetwork tuner with only two controls. .. You get minimum SWR at only one setting and a broadband response that ends constant retuning". [19] "A differential Tmatch antenna tuner", Mike Grierson, G3TSO, Rad Com, Sept 1990, p4849. Constructional article. The differential Tmatch is capable of matching a similar range of impedances to the traditional Tmatch. Efficiency is not discussed. [20] "The Ultimate Transmatch" Lew McCoy W1ICP, QST July 1970 p2427, 58. The use of a roller inductor (as opposed to the then common amateur practice of using switched inductors) gives "almost unlimited" matching range. Uses 1:4 (Z) antennaside balun. Claims efficiency of over 95% for mismatches up to 15:1 with an "adjustable dummy load" [resistor]. [21] "Ultimate Transmatch Improved" Doug DeMaw W1FB, Technical Correspondance, QST July 1980 p39. W1FB states [incorrectly, see 21a] that the original circuit was developed by the James Millen Co. and was popularised in QST by W1ICP as the "Ultimate" transmatch. Goes on to point out that the inputside parallel capacitor is redundant and the circuit is effectively an expensive Tmatch. The problem with the Tmatch is that under some circumstances it degenerates into a highpass filter. Introduces the SPC circuit, which gives better harmonic attenuation and extends the lowfrequency limit. [21a] "Set the Record Straight" Lew McCoy W1ICP, Correspondance, QST March 1981 p56. [22] "The Ultimate vs the SPC Transmatch", Walt Maxwell W2DU, Technical Correspondance, QST Aug 1981 p4243. [23] "Ultimate vs SPC Transmatch" Tech Topics, Rad Com, Sept 1984, p771. G3KSU points out that the 'Ultimate' transmatch is still being advocated in books and journals, despite the shortcomings documented in the technical correspondance columns of QST in July 1980, March 1981, and August 1981. Essentially, the extra shunt capacitance across the TX terminals is useless and causes a reduction in efficiency. The drawback of the Ultimate was overcome by the 'SPC' (SeriesParallel Capacitance) configuration devised by Doug De Maw, W1FB, which offers improved harmonic attenuation [but reduced efficiency] compared to a straight Tnetwork [the SPC configuration was also dropped by the ARRL Antenna Book by the 19th edition]. [24] "Which Transmatch?" Tony Smith G4FAI, Practical Wireless, Aug 1985, p2223. G4FAI Modifies his 'Ultimate' to make it into an SPC. Also briefly discusses the history of the two networks: Lew McCoy W1ICP introduced the 'Ultimate' transmatch in a QST article in [July] 1961 [actually July 1970], several versions appeared in subsequent issues of the ARRL handbook, and commercial versions were produced. The SPC transmatch by Doug DeMaw W1FB appeared in the 1981 ARRL handbook. DeMaw had written to QST in July 1980 pointing out that the Tmatch would function as a HPF under some conditions, and a LPF between TX and transmatch was required. The SPC was developed in an effort to maintain a bandpass response under all load conditions. He claimed better harmonic attenuation and wider range compared to the 'Ultimate', and included details of tests carried out using a spectrum analyser. McCoy responded in March 1981 claiming that the extra 10dB of harmonic attenuation given by the 'Ultimate' was sufficient. In August 1981 [22], Walt Maxwell, W2DU, produced a detailed analysis of both circuits, observing that the input shunting capacitor of the 'Ultimate' was useless for impedance matching and reduced efficiency, but that the circuit did attenuate harmonics slightly. The harmonic attenuation of the SPC was substantially better. The 1983 ARRL handbook observed that harmonic attenuation with the 'Ultimate' can be as low as 3dB under some load conditions; whereas the SPC maintains a bandpass response with loads of <25 to >1000 Ω, this being due to the capacitance in parallel with the inductor. [25] "The ATU Debate Continues" Tech Topics, Rad Com, Dec 1984, p10556. "It would be a brave or foolhardy writer who claimed categorically that any one network was clearly superior to all others". Peter Chadwick, G3RZP, finds the SPC transmatch less eficient than a 4:1 transmissionline transformer and a series capacitor for matching an impedance of 12.5+j22Ω. The problem is that of excessive loaded Q. He prefers a paralleltuned autotransformer, adjusting the working Q by selecting the input and output taps and the L:C ratio, and canceling inductive reactance by means of a series capacitor in the output line. Admits that such tuners require elaborate switching and are not easy to set up. Discusses problem of arcing in unshorted overwinds, and eddy currents in shorted overwinds. Rejects the idea of trying to get harmonic attenuation from an ATU, preferring the efficiency gain from operating the matching network with low working Q. Ivan James, G5IJ, favours the 'Ultimate' transmatch for voltage fed antennas, since the configuration reduces the required voltage rating of the ganged capacitors. Rejects the harmonic attenuation argument and recommends a multisection LPF between the TX and the ATU. Also objects to the 1980 QST harmonic reduction tests, which used a 1000Ω test load for fundamental, 2nd, and 3rd harmonics, pointing out that the antenna impedance is hardly likely to be the same on all three frequencies. "the arguments about harmonic reduction depend so much on the actual antenna impedance that no definite conclusions can be drawn from such tests". Frank Rogers, G3BFR, converted a Tmatch to an SPC and found it extended the lowfrequency limit. The Coil was 27μH, but C values are not given. Also, some material by Rob Gurr, VK5RG, on the Zmatch, is reprinted. [26] "Estimating Tnetwork losses at 80 and 160 meters", Kevin Schmidt, W9CF, QEX, July 1996 p1620. Approximate formulae for estimating losses and peak intermediate voltages of Tnetwork tuners on the basis of inductor Q. This approach indicates that the efficiencies of the basic T and the Ultimate are about the same. The differential T is about a factor of 2 worse than the basic network at low SWR, but becomes similar at high SWR. The SPC is always worse than the basic network, losses being increased by 50% for an SWR of 1, and doubled for low load resistance. Notes that Lnetworks are vastly more efficient at low frequencies when compared to Tnetworks with low maximum capacitance, but have reduced matching range. [27] "Getting the most out of your Tnetwork antenna tuner", Andrew Griffith W4ULD, QST Jan 1995 p4447. Loss is minimised by using the largest possible value for the antennaside capacitor. [28] "How to evaluate your antenna tuner", Frank Witt AI1H, QST April 1995 p3034, May 1995 p3337. Loss estimation method using binary switched load resistors and an SWR meter. [29] The nominal power ratings of antenna tuners of North American origin are generally advertised to be twice the actual PEP rating. The idea is that the instantaneous DC input of a linear amplifier is about twice the PEP output (i.e., class AB amplifiers are about 50% efficient) and so the tuner power rating is the maximum DC input of the associated amplifier. This is a thoroughly silly system, and forces people to make qualfying statements such as: "The tuner is rated for 3KW DC input" (manual tuners do not have a DC input, except perhaps for the panel lamps). We should note, of course, that a tuner doesn't have a meaningful power rating on its own, it depends entirely on the antenna system. [30] Handbook of Leadfree Solder Techology for Microelectronic Assemblies, Karl J Puttlitz, Kathleen A Stalter, CRC Press, 2004. ISBN 0824748700, 9780824748708. Tin degradation phenomena, p925, p929. [31] The cleaning of silver is a job for the Butler, of course. Those unable to delegate can use Goddard's Silver Dip (S C Johnson Ltd), a sulphur sequestering agent. The component should be washed with copious running water after chemical cleaning, and should not be reinstalled untill completely dry. 
Further Reading: 
The ARRL Antenna Book, 19th edition, ARRL publ,
2000. ISBN: 0872598047. Ch 25: Coupling the Transmitter to the Line. Discussion of harmonic attenuation in antenna tuners [pointing out that it is not reliable], and the problem with trapped antennas. Matching circuits: Inductive coupling, Lnetwork, πnetwork, Tnetwork. The 'Analyze Antenna Tuner' Program (supplied on CDROM with the book). Practical antenna tuners: Linkcoupled, Highpower Tnetwork with inputside balun). CD ROM: AAT (Analyze antenna tuner program), etc. The ARRL Handbook 2000, 77th edition. ARRL publ. 1999, ISBN: 0872591832. Ch 13: RF Power Amplifiers Ch 22: Station Setup and Accessory Projects. HighPower Tmatch Antenna Tuner with TXside balun, p5659.) "Antenna matching", Tech Topics, Rad Com, Sept 1981, p818819. Arthur collins, W0CXX, in the mid 1930s, popularised the 'Collins Universal Coupler' (πnetwork), on the basis that any TX could work successfully with any length of antenna. W2DK pointed out that when an antenna element presents to a transmission line an impedance other than R0, the impedance offered to the TX at the other end of the line may be quite different. The feeder acts as an impedance transformer. Unless a matching unit is interposed between the transmitter and the transmission line, the impedance may be of a value with which the TX output circuit cannot cope. An ATU must ideally cope with a very large range of impedances. Only one capacitor and one inductor is required to do this, but values and voltage ratings may become unwieldy. Most ATUs represent configurations aimed at reducing component sizes to manageable proportions. Dr M. J. Underhill, G3LHZ, presented a paper at a Leeds conference, showing that wide range matching can be achieved based on a twostage approach, involving a prematch unit (PMU) at the antenna junction, and a finalmatch unit (FMU) at the transceiver. The PMU may be, for example, a coaxial balun. An FMU design offering switchable πnetwork configurations to keep voltages within reasonable limits is given [see erratum, TT Nov 1981, next ref.]. The series variable capacitance and tapped inductor is suggested as an alternative to the rollercoaster coil. "Antenna matching for amateur bands", Tech Topics, Rad Com, Nov 1981, p1034. Variable capacitor marked 220pF in previous article should have been 2200pF. G3LHZ FMU circuit is reprinted with C1=1600pF (not 2200pF), since amateurs require only 1.830MHz, not 1.530MHz. "The transmitter / antenna Interface" Tech Topics, Rad Com, Dec 1984, p10545. Brief review of antenna coupling practices from early techniques onwards: The widespread introduction of VHF TV after the end of World War II brought about renewed interest in the πnetwork on accountof its lowpass characteristic. The need for better harmonic suppression however soon led to the fixedimpedance lowpass filter, which meant that transmitters were designed to work into a 50Ω load in order to terminate the LPF correctly. The output of the LPF was connected directly to the coax feedline of a resonant antenna. ATUs were relegated for use by those who used endfed wires, openwire feeders, or wanted extra harmonic suppression. The situation changed however with the introduction of solidstate transmitters with protection circuits, which do not give full output with high SWR. Few practical antennas provide sufficiently low SWR over entire amateur bands without the intervention of a matching unit. Consequently, the ATU came back into vogue. G3VA reminds us that a resonant antenna does not radiate any better than a nonresonant one. The new WARC bands make it necessary to be able to cope with a wide range of resistive and reactive load impedances. Repeats information on the G3LHZ PMUFMU approach for those who did not see the 1981 articles (above). Also repeats circuit and information on the G3LHZ widerange FMU. "The PA0SE Comudipole Multiband HF Antenna", Tech Topics, Rad Com, May 1993, p5455. Dick Rollema, PA0SE, notes that it is not always convenient to bring the openwire line into the transmitter room, and recommends a variation of the PMUFMU scheme devised by Mike Underhill, G3LHZ (see "Antenna matching" TT sept. and Nov.1981, and "The Transmitter / Antenna Interface" Dec 1984, above). The G3LHZ information is repeated for those who did not see the 1981 and 1984 articles, giving construction details of a 4:1 aircored coax balun (PMU) for connection via 50Ω coax (SWR <20:1) to a switchconfigurable variable matching network (FMU). PA0SE considers the G3LHZ FMU overcomplicated and adopts a simple switchabe Lnetwork. Describes an installation with a 38m long inverted V dipole using 4:1 coax balun PMU at the antenna, 30m of RG213, and an Lnetwork FMU. Perfect matching is obtained on 10 bands from 1.8  50MHz, but with low efficiency on 1.8MHz. Coax losses may be a few dB on some bands, "but this is a small price to pay for the convenience of a simple all band antenna without traps". The following statements, which appear in the article, are misleading : 1) "The advantage of [the coax] balun over those using ferrite or powdered iron toroids is that there is no danger of saturating the core [only imbalance currents can saturate the core, the fields from the differentialmode currents cancel] 2) "toroidal baluns are not really suitable with reactive loads" [the main problem is insufficient choking reactance when Z is large. Reactive loads increase losses, but the balun transmission line is short, and so the problem is not usually severe]. "PicATUne  the Intelligent ATU." Peter Rhodes, G3XJP, Rad Com, Sep 2000 p1620, Oct 2000 p2125, Nov 2000 p2024, Dec 2000 p2431, Jan 2001 p2124 cont p2930. Summary: Series of 5 articles describing an automatic ATU using only SWR and a search algorithm. Lmatch configuration with high Z  low Z switching is used on the basis of efficiency calculations. Efficiency graphs are given in part 1 (erratum part 4, p31). Design includes welllinearised tapped 30μH solenoid (graph in part 5 p24). Directional coupler is SontheimerFredrick type 9 [US pat. 3426298 fig. 9, incorrectly attributed] used with dummy load on through port and antenna system on reverse port for quiet tuning (citing Underhill & Lewis, Electronic Letters, 4th Jan 1979). "Beyond the ZMatch. The IBZ coupler", Charles A Lofgrenn W6JJZ, Communications Quarterly, Winter (Jan) 1995 p2732. "Appreciating the L Matching Network", Ernie Franke WA2EWT, Ham Radio, Sept 1980 p2630. Theory and applications. "A Multiband Antenna System for the Newcomer" Lew McCoy W1ICP, QST, March 1959 p1115. 3.530MHz balanced coupler using a doubletuned aircored transformer. Selectable series or parallel tuned secondary. "A WideRange Transmatch" Lew McCoy W1ICP, QST, Nov 1961 p5154 3.530MHz 500W coupler using a doubletuned aircored transformer. Series tuned primary, capacitively tapped secondary. "A transmatch for Balanced and Unbalanced Lines" Lew McCoy W1ICP, QST, Oct 1966 p3841. Use of the transmatch to provide selectivity, to prevent harmonic radiation and reduce receiver crossmodulation. 3.530MHz coupler using a doubletuned aircored transformer. Series tuned primary, inductively tapped secondary. "BandSwitching Transmatches" Lance Johnson K1MET, QST 1967 p2224. LCL Tnetwork is used to match 50 Ohm unbalanced lines having SWR of less than 3:1. "Drake MN4 Matching Network" W1DF, QST Oct 1967 p4243. 3.5  30MHz Pi network with additional series capacitor. For matching coaxial lines with up to 5:1 SWR. 
"Graphical solution of impedance matching problems"
I L McNally W1NCK and Henry S Keen W2CTK, Ham Radio Dec 1969
p. Reprinted Mar 1978 p8289. " ", Elmer Wingfield, W5FD, QST, Aug 1983, "A Note on PiL Networks" Elmer Wingfield, W5FD, QEX, Dec 1983 p59 "Analyzing Simple Matching Networks", Mark Bacon, KZ9J, QEX, Feb. 1987, p36, contd, p13. "Selectivity of SingleResonator Coupling Networks", William E Sabin W0IYH, QEX July/Aug 2001 p4347. "Impedance Matching: a brief review", Chris Bowick WD4C, Ham Radio, Jun 1984, p4950, 5356. Maximum powertransfer theorem. The conjugate match. Design of Lnetworks. "Examining the Mechancics of Wave Interference in Impedance Matching", Walter Maxwell W2DU, QEX Mar/Apr 1998, p1724. "VSWR, Reflections, and the "Conjugate" Impedance Match", Dr Steven R Best VE9SRB, Communications Quarterly, Winter (Jan) 1999, p919. "Impedance Matching: Interpreting the Virtual Short Circuit", Dr Steven R Best VE9SRB [Cushcraft], Communications Quarterly, Fall (Oct) 1999, p3156. The virtual shortcircuit idea is wrong. Reflections from the input to the ATU are eliminated by a cancellation process. "Impedance Matching: Interpreting the Virtual Short Circuit (re: Communications Quarterly, Fall 1999): QEX (Letters to the Editor) Sept/Oct 2000, p6062 Walter Maxwell W2DU. Dr Steven R Best VE9SRB. "Wave Mechanics of Transmission Lines, Part 1: Equivalence of Wave Reflection Analysis and the TransmissionLine Equation", Dr Steven R Best, VE9SRB, QEX Jan/Feb 2001, p38. "Wave Mechanics of Transmission Lines, Pt 2: Where Does Reflected Power Go", Dr Steven R Best, VE9SRB, QEX July/Aug 2001, p3442. "Wave Mechanics of Transmission Lines, Part 3: Power Delivery and Impedance Matching", Dr Steven R Best, VE9SRB, QEX Nov/Dec 2001, p4350. Correspondence, Lincoln Kraeuter KB1EYQ, QEX July/Aug 2002, p61. 
πnetworks
for power amplifiers: "Pinetwork design for highfrequency power amplifiers" Irvin M Hoff W6FFC, Ham Radio, Sept. 1972 . Reprinted June 1978 p5264 "Pi Network Design and Analysis", Earl W Whyman W2HB, Ham Radio, Sept 1977, p30 "Pi Network Design", Leonard H Anderson, Ham Radio, March 1978 p3640. πnetworks for transmitter output stages. "Transmitter Matching Networks" Irvin M Hoff W6FFC, Ham Radio, March 1978 p4246. Networks for matching an exciter to the input impedance of a linear amplifier. "Optimum pinetwork design", Ulrich Fleischmann DL9LX, and Leonard H Anderson, Ham Radio Sept 1980, p5056. Methods for optimising bandwidth without using the Q factor. Use of Zplane diagram to illustrate the transformation process. "PiNetwork Formulas", Elmer Wingfield W5FD, (Correspondence) QEX Sept 1982, p2. Comments on defective pnetwork design formulae published in various amateur radio books and journals. "More on PiNetwork Formulas", Mason A Logan, K4MT, (Correspondence) QEX Dec 1982, p2. Corrections to the above. Seriesparallel and parallel series transformations. "New and Improved Formulas for the Design of Pi and PiL Networks", Elmer A Wingfield W5FD, QST Aug 1983 p23 "Impedance Matching  A Brief Review", Chris Bowick W4DC, Ham Radio, June 1984, p48 Walt Maxwell W2DU, Technical Correspondence, QST, Mar 1985, p45. "Design a toroidal tank circuit for your vacuum tube amplifier", Robert E Bloom W6YUY, Ham Radio, Aug 1985, p2931, 3336. Full design procedure for amplifiers up to 2KW. "Pi Network Capacitor Equations", Mason A Logan, K4MT, Ham Radio, Oct 1988, p109110. "A Concise Calculation Method for PiL Networks", Karl Gerhard Lickfeld, DL3FM, QEX Sept/Oct 1998 p4749. "A Concise Calculation Method for PiL Networks" William H Sayer WA6BAN, Doug Smith KF6DX (Editor), (Correspondence) QEX March/April 1999, p5960. Errors in Lickfield's article. "A Concise Calculation Method for PiL Networks" Vince Bartell W0MFK (Correspondence) QEX, May/June 1999, p61. Lickfield's method is flawed. 



