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1. [TowerTalk] Johnson Matchbox (score: 1): Author: cebik@utkux.utcc.utk.edu (L. B. Cebik); Date: Sat, 1 Nov 1997 09:52:14 -0500 (EST); I have heard the Johnson Matchbox described as a modified Z match, which is not quite right. Having just obtained one, I thought I might describe the circuit, which appears to be very similar to the; /archives//html/Towertalk/1997-11/msg00007.html (10,776 bytes)
2. [TowerTalk] Johnson Matchbox (score: 1): Author: "Tom Osborne" <w7why@verizon.net>; Date: Sun, 16 Mar 2008 14:38:12 -0700; Hi All I just purchased a 275 watt Johnson Matchbox, almost mint condition. They are rated at 275 watts, but the components inside look pretty hefty. Has anyone ever run more than 275 watts into one; /archives//html/Towertalk/2008-03/msg00273.html (7,318 bytes)
3. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: W6SX Hank Garretson <w6sx@npgcable.com>; Date: Sun, 16 Mar 2008 14:50:11 -0700; It has been fifty years, but my Elmer used to run 500 watts into one of these. He never had any problems. He did emphasize that he tuned it up at low power. 73, Hank, W6SX Mammoth Lakes, California _; /archives//html/Towertalk/2008-03/msg00274.html (7,329 bytes)
4. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: "Jim Miller" <JimMiller@STL-OnLine.Net>; Date: Sun, 16 Mar 2008 17:37:37 -0500; I think you will find that they were rated for AM in those days. Check it out. Will handle a lot more in SSB. 73,de Jim KG0KP _______________________________________________ _________________________; /archives//html/Towertalk/2008-03/msg00277.html (8,295 bytes)
5. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: "Scott MacKenzie" <kb0fhp@comcast.net>; Date: Sun, 16 Mar 2008 19:19:16 -0400; There was an article in QST several years ago, where they indicated that it was rated for AM service with a lot of extra heft for additional safety.... I think you will find that they were rated for; /archives//html/Towertalk/2008-03/msg00279.html (9,501 bytes)
6. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: n8de@thepoint.net; Date: Sun, 16 Mar 2008 20:00:13 -0400; TGhe polystyrene spacer used to hold the coil in place will melt and distort under conditions which cause the coil to heat much above ambient. I wouldn't run RTTY through it above the rated power, th; /archives//html/Towertalk/2008-03/msg00283.html (9,068 bytes)
7. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: Bill MacLane <ai4wm@yahoo.com>; Date: Mon, 17 Mar 2008 02:37:41 -0700 (PDT); If only the junk today was made like these... I have one and it handles 500 watts easily. Tune it at low power and get a good match and it'll handle more power than the tuners available today. These; /archives//html/Towertalk/2008-03/msg00291.html (8,440 bytes)
8. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: "Rick Karlquist" <richard@karlquist.com>; Date: Mon, 17 Mar 2008 10:04:15 -0700 (PDT); An historical note: Johnson sold a transmitter rated at 275W, DC power input. It was called the Valiant or something like that. I believe this is where the 275W came from (ever wondered why not 250 o; /archives//html/Towertalk/2008-03/msg00299.html (8,691 bytes)
9. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: W6SX Hank Garretson <w6sx@npgcable.com>; Date: Mon, 17 Mar 2008 10:55:55 -0700; If you're saying the Matchbox rating was based on the Valiant, that can't be because the Matchbox predated the Valiant. It could be that the Valiant rating was based on the Matchbox rating. 73, Hank,; /archives//html/Towertalk/2008-03/msg00301.html (8,316 bytes)
10. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: Robert Hess <w1rh@yahoo.com>; Date: Mon, 17 Mar 2008 14:02:52 -0700 (PDT); I already answered this via a private email, but for the record, I have had a 275 watt Matchbox since I was a teenager. Bought it used. I have been running an honest 1.5 KW into it for at least 20 ye; /archives//html/Towertalk/2008-03/msg00306.html (10,282 bytes)
11. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: "Tom Osborne" <w7why@verizon.net>; Date: Sun, 23 Mar 2008 21:32:43 -0700; Howdy TT'ians Got the Matchbox hooked up this weekend and ran it in the BARTG RTTY contest. Ran 500 watts with the SB-200 and it didn't even get warm. Guess it will take lots more than 275 watts! Sta; /archives//html/Towertalk/2008-03/msg00445.html (8,342 bytes)
12. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: "Jim Brown" <jim@audiosystemsgroup.com>; Date: Sun, 23 Mar 2008 21:59:49 -0700; Dissipation depends on the voltage and current in individual components, which in turn depends on the exact values of complex impedances being transformed, the frequency, and, of course, the power le; /archives//html/Towertalk/2008-03/msg00446.html (8,470 bytes)
13. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: Bill N1eY <whobulk3@comcast.net>; Date: Mon, 24 Mar 2008 07:19:22 -0400; Well, aren't there two versions of the Johnson Matchbox? One was lower power and the other was QRO. _______________________________________________ _______________________________________________ Tow; /archives//html/Towertalk/2008-03/msg00448.html (8,808 bytes)
14. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: <sabrams@nycap.rr.com>; Date: Mon, 24 Mar 2008 08:48:09 -0400; Many years ago I ran a Heath Warrior at 800w thru my 250 Matchbox and it never got warm, but when I looked inside, the plastic(?) coil form had melted around the coil wires . Check inside! GL 73 Saul; /archives//html/Towertalk/2008-03/msg00449.html (9,565 bytes)
15. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: Bill MacLane <ai4wm@yahoo.com>; Date: Mon, 24 Mar 2008 17:27:57 -0700 (PDT); Yes, One was 275W and on 1000W. Both rated for AM. _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http; /archives//html/Towertalk/2008-03/msg00453.html (9,731 bytes)
16. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: jim Jarvis <jimjarvis@optonline.net>; Date: Tue, 25 Mar 2008 11:15:57 -0400; TT, Some added thoughts on this: The Johnson matchboxes were rated at a time when the FCC power rules were based on INPUT power, not output. So, the 275W version matched the specs for the Valiant, an; /archives//html/Towertalk/2008-03/msg00463.html (9,366 bytes)
17. Re: [TowerTalk] Johnson Matchbox (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 25 Mar 2008 12:00:46 -0400; With AM modulation the plate voltage doubles with 100% modulation so peak envelope power is increased by a factor of 4. With the plate modulated AM transmitter having an efficiency around 70% or so,; /archives//html/Towertalk/2008-03/msg00464.html (11,814 bytes)

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