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Total 57 documents matching your query.

21. Re: [Amps] 4CX250 IMD (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Fri, 28 Sep 2007 10:45:02 +0100; Looking at GW4FRX's measurements, I wonder if the IMD you measured owed more to the screen supply than to the tubes themselves? The old Was that the new version or the older one in the diecast box? S; /archives//html/Amps/2007-09/msg00455.html (8,244 bytes)
22. Re: [Amps] 4CX250 IMD (score: 1): Author: "jeremy-ca" <km1h@jeremy.mv.com>; Date: Fri, 28 Sep 2007 09:37:21 -0400; 250/245 ma and 262/470 W PEP Note they specify PEP. There is also a "worst case" 3rd order line entry of -29/21dB. With the tendency to use these tubes (the full 250 family)at their maximum voltage a; /archives//html/Amps/2007-09/msg00458.html (9,646 bytes)
23. Re: [Amps] 4CX250 IMD (score: 1): Author: "jeremy-ca" <km1h@jeremy.mv.com>; Date: Fri, 28 Sep 2007 09:50:01 -0400; Looking at the Eimac data it doesnt appear that the VR tubes had much effect but that was back in my BC days. Im guessing that they did their measurements with VR tubes also. Later testing did show i; /archives//html/Amps/2007-09/msg00459.html (9,457 bytes)
24. Re: [Amps] 4CX250 IMD (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Fri, 28 Sep 2007 17:53:29 +0200 (CEST); I ahev a feeling that although at HF, the application of negative feedback to significantly improve the IMD is practicable, doing so at VHF might be somewhat different. Other than unbypassed cathode; /archives//html/Amps/2007-09/msg00461.html (7,131 bytes)
25. Re: [Amps] 4CX250 IMD (score: 1): Author: "jeremy-ca" <km1h@jeremy.mv.com>; Date: Fri, 28 Sep 2007 11:58:37 -0400; I wouldnt even think about trying that on this amp. Sorry if I wasnt plain about that. Carl KM1H _______________________________________________ Amps mailing list Amps@contesting.com http://lists.con; /archives//html/Amps/2007-09/msg00462.html (8,240 bytes)
26. Re: [Amps] 4CX250 IMD (score: 1): Author: Colin Lamb <k7fm@teleport.com>; Date: Fri, 28 Sep 2007 08:58:36 -0700 (GMT-07:00); "in a repeatable and stable manner" You are a tough guy to please, Peter Colin K7FM _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/m; /archives//html/Amps/2007-09/msg00463.html (7,376 bytes)
27. Re: [Amps] 4CX250 IMD (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Fri, 28 Sep 2007 18:23:21 +0200 (CEST); Now why is it that I totally agree? Maybe Harry Potter could do these tricks.....but not us mere mortals. 73 Peter G3RZP _______________________________________________ Amps mailing list Amps@contest; /archives//html/Amps/2007-09/msg00466.html (7,518 bytes)
28. Re: [Amps] 4CX250 IMD (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Fri, 28 Sep 2007 17:54:55 +0100; Single tube or pair? Thanks, Steve _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps; /archives//html/Amps/2007-09/msg00467.html (9,113 bytes)
29. Re: [Amps] 4CX250 IMD (score: 1): Author: "jeremy-ca" <km1h@jeremy.mv.com>; Date: Fri, 28 Sep 2007 13:13:36 -0400; That rating is for AB1 SSB service, 2KV@ 250ma is the listed typical operation for one tube as with all in the straight 4CX250W family. Carl KM1H _______________________________________________ _____; /archives//html/Amps/2007-09/msg00470.html (10,187 bytes)
30. Re: [Amps] 4CX250 IMD (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sat, 29 Sep 2007 08:45:16 +0100; Pushing a 4CX250 to 470W pep output is absurd and it's no surprise that the IMD is awful. It's totally unrepresentative of proper use of the tube in linear operation. Collating all the info. we've b; /archives//html/Amps/2007-09/msg00473.html (9,791 bytes)
31. Re: [Amps] 4CX250 IMD (score: 1): Author: "jeremy-ca" <km1h@jeremy.mv.com>; Date: Sat, 29 Sep 2007 09:12:07 -0400; The tube is being tested in AB1, ZERO grid current, therefore Eimac is not overdriving it. They are simply showing the degradation when the tube is run at its TYPICAL rating of 2KV. I have no idea ho; /archives//html/Amps/2007-09/msg00474.html (11,468 bytes)
32. Re: [Amps] 4CX250 IMD (score: 1): Author: "Peter Voelpel" <df3kv@t-online.de>; Date: Sat, 29 Sep 2007 15:31:05 +0200; 4CX250B run quite well at 1500V anode voltage in the Racal TA1800 to drive the 4CX10000D. One 4CX350A works as a wide band pre driver, two in parallel are the tuned driver tubes. The amp is run with; /archives//html/Amps/2007-09/msg00475.html (9,333 bytes)
33. Re: [Amps] 4CX250 IMD (score: 1): Author: "w6duv" <w6duv@planet.nl>; Date: Sat, 29 Sep 2007 17:00:37 +0200; Same for the Collins 204C. Both the 4CX250B pre driver (Class A) and the 4CX250B driver (Class AB) run with 1500 VDC plate voltage and drive the 4CX5000 final tube. Cheers, Dick PA3DUV W6DUV ________; /archives//html/Amps/2007-09/msg00481.html (11,017 bytes)
34. Re: [Amps] 4CX250 IMD (score: 1): Author: Steve Thompson <g8gsq@eltac.co.uk>; Date: Sat, 29 Sep 2007 17:28:46 +0100; OK - it was a figure of speech. Please substitute 'at 470W' for 'with massive overdrive'. and at much higher output power. The IMD goes bad because the tube is being pushed to deliver too much power,; /archives//html/Amps/2007-09/msg00488.html (13,009 bytes)
35. Re: [Amps] 4CX250 IMD (score: 1): Author: "Tom Rauch" <w8ji@contesting.com>; Date: Sat, 29 Sep 2007 14:02:41 -0400; That is correct. People are comparing an entirely different set of parameters, not just a voltage increase alone. It is the output power increase that is largely responsible for higher IM, although; /archives//html/Amps/2007-09/msg00492.html (11,434 bytes)
36. Re: [Amps] 4CX250 IMD (score: 1): Author: "jeremy-ca" <km1h@jeremy.mv.com>; Date: Sat, 29 Sep 2007 15:51:12 -0400; What both of you continuously fail to understand is that the tube is being run within its manufacturers published ratings. No amount of side stepping can change that fact. It is also an established f; /archives//html/Amps/2007-09/msg00496.html (10,781 bytes)
37. Re: [Amps] 4CX250 IMD (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Sat, 29 Sep 2007 21:43:45 -0500; You guys are not reading the spec sheets right. As to power at different voltages, they show a maximum plate current of 250 ma at 1500 volts and also at 2000 volts. Of course power is greater at the; /archives//html/Amps/2007-09/msg00501.html (14,184 bytes)
38. Re: [Amps] 4CX250 IMD (score: 1): Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>; Date: Sun, 30 Sep 2007 09:53:44 +0200 (CEST); RCA rate the 4CX250B at 295 watts PEP output through a 95% efficient tank circuit with 2000volts on the plate and -30dB 3rd order products, although it doesn't say if that is -30dB with respect to on; /archives//html/Amps/2007-09/msg00503.html (7,663 bytes)
39. Re: [Amps] 4CX250 IMD (score: 1): Author: "jeremy-ca" <km1h@jeremy.mv.com>; Date: Sun, 30 Sep 2007 08:34:01 -0400; Those last three sentences make absolutely no sense. Input power is 500WDC, Output is 470W PEP, not key down CW. I'll use CW since some seem to be getting confused with single and two tone reference; /archives//html/Amps/2007-09/msg00506.html (9,753 bytes)
40. Re: [Amps] 4CX250 IMD (score: 1): Author: "Peter Voelpel" <df3kv@t-online.de>; Date: Sun, 30 Sep 2007 15:00:18 +0200; That´s the efficiency I always wanted to obtain! 73 Peter Input power is 500WDC, Output is 470W PEP, not key down CW. _______________________________________________ Amps mailing list Amps@cont; /archives//html/Amps/2007-09/msg00509.html (8,659 bytes)

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