Nuts and Volts

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(Un)MATCHED PAIRS OF TUBES

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Jack Lemieux

PUBLISHER Larry Lemieux publisher@nutsvolts.com

ASSOCIATE PUBLISHER/ VP OF SALES/MARKETING Robin Lemieux display@nutsvolts.com

EDITOR Bryan Bergeron techedit-nutsvolts@yahoo.com

CONTRIBUTING EDITORS

Jeff Eckert Russ Kincaid Joe Pardue Fred Eady Ron Hackett Louis Frenzel Louis Dratwa Craig Lindley Gerry Shand

I just got caught up on some of my reading yesterday, and have a story about matched pairs you might find amusing; it’s a memory triggered by your March editorial. Fifty years ago when I was in high school, we had a decent — for the time — stereo system powered by two Dyna Mark IIIs, which took KT88s. My brother insisted we buy matched pairs, so we got them from a company whose name was something like Gold Lion. Whatever kind of “lion” they were, they may also have been lying.

The spec sheets that came with each tube — with their little red check marks for each tested specification — were a perfect match, check inflection to check inflection. In fact, when my brother reordered another pair a couple years later, the spec sheets were identical to those of the earlier tubes (yes, I kept those spec sheets for reference).

I had no way to tell if the tubes were matched because — back then — I only had a simple good-bad vacuum tube tester.

My brother and I were also both hams at the time, and I later went into stereo repair at the dawn of the transistor era with soldiers coming back in droves from Vietnam, with stereo equipment from Japan in tow.

(A childhood and current friend of mine still has his Sansui system that he brought back with him).

I segued out of electronic repair at the dawn of the integrated circuit era as repair became must less challenging to me, and got into microprocessor system design and programming. I segued out of that into custom computer system programming, which I stayed in until I retired a few years ago.

I have a lifetime subscription to NV, which I cherish. Is there another magazine that even comes close to supporting the electronic hobbyist?

Although my tinkering days are over, I do enjoy reading the design articles and keeping up with the latest in µP technology. I will probably never (in reality) lick a Stamp or take a Propeller for a spin, but I do so vicariously in your pages. Keep up the great work.

Steve Borsher

CIRCULATION DEPARTMENT subscribe@nutsvolts.com

SHOW COORDINATOR Audrey Lemieux

MARKETING COORDINATOR WEBSTORE Brian Kirkpatrick sales@nutsvolts.com

WEB CONTENT Michael Kaudze website@nutsvolts.com

ADMINISTRATIVE ASSISTANT Debbie Stauffacher

PRODUCTION Sean Lemieux

Thanks for sharing. I guess human nature hasn't changed much in the past 50 years. My first real experience with tubes was with a Heathkit DX60B transmitter (6146A tube). I had other tube-type equipment before then, but I really learned to know the tube.

Peak the grid and dip the plate ...

If there's something you think we should cover (more tubes?), please let me know.

Bryan Bergeron, Editor

DC Power Supplies NEW! DP800

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