Folks, I recall comparisons and analysis of different tuner types done several years ago by ARRL. The conclusion was that the inductor Q was the major determining factor for tuner efficiency of any one type of tuner. The T match circuit can match a large range but at some settings can produce high circulating currents leading to very high losses, the PI network is generally low loss but at the expense of failing to match very low impedance loads with reasonable value capacitors, the L network is quite efficient, but the lowest loss is a link coupled tuned tank circuit type tuner with a high Q inductor (i.e. Johnson Matchbox type).
IMHO, compact designs have produced more tuner losses than any other contributing factor - Hi-Q inductors are generally large airwound fixed coils spaced far away from conducting surfaces. I look at my Johnsom Matchbox and see an air-wound coil supported in the center of a large box (the coil has lots of surrounding empty space), quite in contrast to my MFJ T match circuit tuner with the roller inductor placed less than an inch from the side, bottom and top of the enclosure - the front panel appearance of that tuner was judged more important than minimizing the inductor loss - and we call it progress!!! Contrary to popular belief, balun loss is not the largest contributing factor, and if properly designed, makes little difference whether it is placed on the input or the output. Charles Green W1CG has done a lot of work on balun loss and reports that the loss is actually quite low (even when their design impedance is severly mismatched). My bottom line conclusion here is that we pay a price in efficiency for the convenience of compactness and a large matching range. While I have not seen efficiency tests of the Elecraft tuners, I would venture to guess that their L network design with switched toroid inductors would show a relatively low loss compared to many other designs. 73, Don W3FPR > -----Original Message----- > > I haven't had lots of different tuners to compare myself, but I do have > a Johnson KW Matchbox tuner. It does a great job on Balanced lines. I > didn't really know about the Palastar but just checked it out on the > website. Looked like an interesting tuner. But to me the downside of > it was that there is a balun on the output, which of course as Don > stated is a dominating factor in losses in a tuner (at least maybe that > is what I took away from his comments as well as other discussions on > this subject in the past). Is there a modern tuner out there for > balanced lines that doesn't use a balun? > > Maybe the proper comparison for more apples to apples comparison should > be made for tuners that are designed for type of feedline output or > maybe Hi-Z vs Lo-Z, as most today, including the Elecraft, are likely > ... -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.308 / Virus Database: 266.11.9 - Release Date: 5/12/2005 _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
