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References: [ +subject:/^(?:^\s*(re|sv|fwd|fw)[\[\]\d]*[:>-]+\s*)*\[Amps\]\s+Designing\s+the\s+Cleanest\s+Linear\s+with\s+RF\s+Negative\s+Feedback\s*$/: 84 ]

Total 84 documents matching your query.

61. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Mon, 19 Dec 2005 12:32:08 -0500
Hi Marv, Gee, that feed forward correction method sounds like something that would be ideal for the FT-1000D. As you said, it could be later moved from rig to rig too. So far all I've seen on the web
/archives//html/Amps/2005-12/msg00261.html (10,202 bytes)

62. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Karl-Arne Markstr&ouml;m <sm0aom@telia.com>
Date: Mon, 19 Dec 2005 19:16:52 +0100
Feed-forward correction is a very powerful, but somewhat involved distorsion reduction technique. For more information, and some worked examples, see chapter 13 "Ultra-low distorsion power amplifiers
/archives//html/Amps/2005-12/msg00264.html (13,195 bytes)

63. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "wc6w@juno.com" <wc6w@juno.com>
Date: Mon, 19 Dec 2005 20:07:17 GMT
Hi Tom, First, I've never seen a feed forward correction system implemented for HF so, I can't point you to any done circuits. It may be because it's a futile undertaking. I don't know of any amateur
/archives//html/Amps/2005-12/msg00265.html (11,578 bytes)

64. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Mon, 19 Dec 2005 16:29:00 -0500
Karl-Arne, OK on the caution needed regarding obtaining these high IMD numbers. Good advice, OM. I would say that the level of distortion I heard when listening to the 5mW level coming out of the FT-
/archives//html/Amps/2005-12/msg00266.html (10,404 bytes)

65. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Tue, 20 Dec 2005 14:46:03 -0500
I called some ham friends looking for 4CX-350's drivers for the tetrode linear project. One of the guys has some 8560A's, with sockets, heatsinks, etc. that I can swap some stuff for. These are the c
/archives//html/Amps/2005-12/msg00275.html (10,400 bytes)

66. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Steve Thompson <g8gsq@eltac.co.uk>
Date: Wed, 21 Dec 2005 10:19:41 +0000
The STC data for 4CX250B gives typical values for class AB1: 2kV anode, 350V screen, 100mA Iq. 2 tone Po 325W pep, IMD3 -30dBc, IMD5 -50dBc. Same IMD at 1500V anode, 225W pep out. The power levels me
/archives//html/Amps/2005-12/msg00280.html (11,082 bytes)

67. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Wed, 21 Dec 2005 11:52:49 -0500
That's the info I needed, Steve! -30 db IMD at 300+ watts. Yes, as you said, the 8560's [4CX-250's] will be used as class A voltage drivers putting out barely a watt or two, and 30 volts of swing. Th
/archives//html/Amps/2005-12/msg00283.html (13,190 bytes)

68. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Gary Schafer <garyschafer@comcast.net>
Date: Wed, 21 Dec 2005 11:54:59 -0500
Those figures are too good for a 4cx250B. They are probably referencing to pep. Looking in the (older version) "care and feeding of power grid tubes" they show the 4CX250B at 348 watts pep output to
/archives//html/Amps/2005-12/msg00284.html (13,307 bytes)

69. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Wed, 21 Dec 2005 12:06:49 -0500
Gary, Yes, I've read that too, but then I've read the opposite.. That statement above would make my question about using a chain of GG tubes running at 1/10th reduced ratings a poor idea. I'm a litt
/archives//html/Amps/2005-12/msg00285.html (11,197 bytes)

70. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Steve Thompson <g8gsq@eltac.co.uk>
Date: Wed, 21 Dec 2005 17:46:40 +0000
The data sheet is explicit in specifying the levels as relative to each tone. In my experience, STC brand 4CX250s do come close to this. There's a scanned version at www.g8wrb.org It's ok to referenc
/archives//html/Amps/2005-12/msg00286.html (13,702 bytes)

71. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Steve Thompson <g8gsq@eltac.co.uk>
Date: Wed, 21 Dec 2005 17:56:09 +0000
I think it's important to consider the difference between the class AB biassing that we are all used to in our amplifiers, and true class A which is usually reserved for specialist ultra-linear requi
/archives//html/Amps/2005-12/msg00287.html (11,518 bytes)

72. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Gary Schafer <garyschafer@comcast.net>
Date: Wed, 21 Dec 2005 21:07:17 -0500
Yes I see you are right Steve. I don't know where I got it from that changing one tone would give those parameters. Must of had a bad dream. I do remember that receivers always have the characteristi
/archives//html/Amps/2005-12/msg00292.html (15,495 bytes)

73. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Thu, 22 Dec 2005 07:55:16 +0000
tubes" is located? http://www.cpii.com/eimac/eiapps.htm The link to "Son of C&F" is at the top of the page. Also see the links to many of our other favorite topics. -- 73 from Ian GM3SEK 'In Practice
/archives//html/Amps/2005-12/msg00293.html (10,761 bytes)

74. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Steve Thompson <g8gsq@eltac.co.uk>
Date: Thu, 22 Dec 2005 09:25:11 +0000
Yes - although IMD5 (or higher order) is rarely significant with class A amps running low IMD3. Very! It's a whole new world where driver stages are much bigger than you think they need to be. Say yo
/archives//html/Amps/2005-12/msg00294.html (11,205 bytes)

75. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Thu, 22 Dec 2005 10:34:14 +0000
Reminds me of a certain K5 station asking a European moonbouncer: "Whaddya runnin'?" "A 4CX250 --" "Geez, whaddya drivin' with THET?" (It wasn't K5GW, but Gerald will know the voice :-) -- 73 from Ia
/archives//html/Amps/2005-12/msg00295.html (10,619 bytes)

76. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Thu, 22 Dec 2005 12:35:33 -0500
Very interesting comments. It certainly IS an eye opener when you see what each driver plate dissipation needs to be for an all class A chain. But an easy way to maintain high IMD figures. I'm consid
/archives//html/Amps/2005-12/msg00296.html (11,988 bytes)

77. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Thu, 22 Dec 2005 14:17:48 -0500
Please disregard my question below: "Would there be a major disadvantage to running the whole tetrode chain in GG with standard voltages on the grid and screen? It seems it would be much easier to ta
/archives//html/Amps/2005-12/msg00297.html (12,006 bytes)

78. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: "Tom Cathey" <K1JJ@comcast.net>
Date: Thu, 22 Dec 2005 20:29:31 -0500
Just to keep the reflector updated with info... I received a few private emails regarding using a chain of hi mu GG tubes in cascade. The general consensus is that it was not a very good idea. One re
/archives//html/Amps/2005-12/msg00300.html (9,780 bytes)

79. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: Steve Thompson <g8gsq@eltac.co.uk>
Date: Fri, 23 Dec 2005 11:11:53 +0000
A few thoughts covering several recent posts: Stability with tetrode amps should not be a problem if you use ceramic tubes with the proper bases. More than anything, I think it's the lead length in g
/archives//html/Amps/2005-12/msg00304.html (9,512 bytes)

80. Re: [Amps] Designing the Cleanest Linear with RF Negative Feedback (score: 1)
Author: R.Measures <r@somis.org>
Date: Fri, 23 Dec 2005 06:07:58 -0800
For VHF and UHF amplifiers, I found this to be true, but for HF ones, to my surprise, things blew. As I see it, whereas lanky glass-tubes can have VHF parasites, compact ceramic ones can have UHF par
/archives//html/Amps/2005-12/msg00305.html (9,591 bytes)


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