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41. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "John Vickers" <wa4tt@nlamerica.com>; Date: Tue, 29 Aug 2006 00:18:54 -0400; That was my point Rich. Mikey stated he needed a nichrome suppressor to tame it. Seems to me the problem was elsewhere and the suppressor just patched it. ____________________________________________; /archives//html/Amps/2006-08/msg00752.html (10,594 bytes)
42. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: R L Measures <r@somis.org>; Date: Mon, 28 Aug 2006 20:27:12 -0700; L-supp is the inductive branch of an L/R suppressor. R L MEASURES, AG6K. 805-386-3734 r@somis.org _______________________________________________ Amps mailing list Amps@contesting.com http://lists.co; /archives//html/Amps/2006-08/msg00753.html (8,461 bytes)
43. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Tue, 29 Aug 2006 07:38:13 +0100; What rise/fall time is needed to start something ringing at (say) 120MHz? Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mail; /archives//html/Amps/2006-08/msg00754.html (8,307 bytes)
44. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Tue, 29 Aug 2006 10:52:12 +0200 (CEST); There are a number of things I don't understand about the parasitic suppression business. According to Terman, a tuned amplifier with a plate circuit tuned LF of the grid circuit is unconditionally s; /archives//html/Amps/2006-08/msg00755.html (9,433 bytes)
45. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 29 Aug 2006 05:41:15 -0400; unconditionally stable because the grid has a positive input resistance. If the grid is tuned LF of the plate, it has a negative input resistance. On this basis then, a tube with a good short grid co; /archives//html/Amps/2006-08/msg00757.html (11,173 bytes)
46. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "k7fm" <k7fm@teleport.com>; Date: Tue, 29 Aug 2006 06:30:37 -0700; Lsup means limp suppository. Rsup means rigid suppository. Colin K7FM _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listin; /archives//html/Amps/2006-08/msg00760.html (8,392 bytes)
47. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: R L Measures <r@somis.org>; Date: Tue, 29 Aug 2006 02:42:51 -0700; What is the reactance of C-feedback in an 8877 at 500MHz? Not everything we did in the 1950s was well thought out, Peter. To see it, one converts the R/L suppressor's series R to Rp, its parallel-equ; /archives//html/Amps/2006-08/msg00765.html (10,186 bytes)
48. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: R L Measures <r@somis.org>; Date: Tue, 29 Aug 2006 02:51:22 -0700; Any change in current causes a resonant circuit to ring. Ringing amplitude depends on how fast the current changes and on Q. Faster and more Q =s more V. I have heard from more than a few TL-922 owne; /archives//html/Amps/2006-08/msg00766.html (9,965 bytes)
49. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "Mike Sawyer" <w3slk@uplink.net>; Date: Tue, 29 Aug 2006 12:27:02 -0400; "813s don't need a VHF suppressor because they are pushing the limit at 28MHz." On the contrary, I remember seeing a single 813 amp for 50Mhz in a handbook somewhere. Also, my problem was spur genera; /archives//html/Amps/2006-08/msg00773.html (9,703 bytes)
50. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 29 Aug 2006 14:51:46 -0400; That's exactly opposite the truth anyway. The most stable tubes are those with the highest operating frequency limits. 73 Tom _______________________________________________ Amps mailing list Amps@c; /archives//html/Amps/2006-08/msg00779.html (9,919 bytes)
51. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: Colin Lamb <k7fm@teleport.com>; Date: Tue, 29 Aug 2006 12:30:43 -0700 (GMT-07:00); _____________________ Old time home brewers will remember the 6AG7. I think the max frequency for full ratings is something like 10 MHz (whoops it was Mc). They are one of the worst offenders I have; /archives//html/Amps/2006-08/msg00782.html (8,825 bytes)
52. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: Bill Turner <dezrat@copper.net>; Date: Tue, 29 Aug 2006 15:55:36 -0700; ORIGINAL MESSAGE: -- REPLY FOLLOWS -- Indeed I do. A wonderful tube, but not for RF. It was originally designed as a resistance-coupled amplifier for video output circuits in the early black and whit; /archives//html/Amps/2006-08/msg00785.html (8,442 bytes)
53. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Wed, 30 Aug 2006 09:56:24 +0200 (CEST); Bill said: (re 6AG7) in the early black and white TV sets< I think it was out shortly before the end of WW2 as a video amp/driver for radar purposes - a very similar application. Its little brother i; /archives//html/Amps/2006-08/msg00791.html (8,791 bytes)
54. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Wed, 30 Aug 2006 10:13:12 +0200 (CEST); Made of resistance wire, it is. If it isn't, then the measurements Wes did, which show an impedance that increases with frequency, are wrong. 73 Peter G3RZP __________________________________________; /archives//html/Amps/2006-08/msg00793.html (8,290 bytes)
55. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 30 Aug 2006 05:57:25 -0400; It's easy to see the series resistance added by the nichrome primarily affects low frequency performance, and has a decreasing effect as frequency is increased. The correct term for a nichrome suppr; /archives//html/Amps/2006-08/msg00794.html (10,388 bytes)
56. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Wed, 30 Aug 2006 11:21:54 +0100; Sure, but how fast does the current change? By the time the decoupling capacitors have charged to allow the tube to drift into cutoff, I doubt the rise time alone is going to make the anode ciruit ri; /archives//html/Amps/2006-08/msg00796.html (10,779 bytes)
57. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "Mike Sawyer" <w3slk@uplink.net>; Date: Wed, 30 Aug 2006 07:33:27 -0400; Rich asked, "Did the 813 have a metal anode or a carbon anode?" They were the familiar RCA's with the thick carbon plate. Mod-U-Lator, Mike(y) W3SLK _______________________________________________ Am; /archives//html/Amps/2006-08/msg00799.html (9,692 bytes)
58. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 30 Aug 2006 07:40:20 -0400; That can be because of relay sequencing. Known to be a problem in the stock TL922. Because of bypass caps and other component values, the ringing can never have a higher peak at VHF than it has at H; /archives//html/Amps/2006-08/msg00800.html (10,461 bytes)
59. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Wed, 30 Aug 2006 21:17:15 +0100; I wish I could reproduce that. I've tried repeatedly with spectrum analyser and 'scopes and only ever find operating frequency ringing, even with suppressors removed. I've tried with a couple of amp; /archives//html/Amps/2006-08/msg00824.html (10,861 bytes)
60. Re: [Amps] Parasitics & Filament Sag (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 30 Aug 2006 19:45:04 -0400; I can't, except my comments below: It sounds illogical or false to me. One thing we do know for sure is the bias circuit can only charge and cut the tube off at the rate the filament choke common mo; /archives//html/Amps/2006-08/msg00826.html (12,695 bytes)

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