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1. Re: [Amps] SELL: Ameritron AL1200 Contestor's Amplifier (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sat, 24 Jun 2006 20:05:39 -0400; At 2000w out with 120W of drive and 250mA of indicated Ig, grid dissipation is only about 30W with a peak emission current at the crest of the cycle of about 4 amps. Contrary to authoritative guesse; /archives//html/Amps/2006-06/msg00352.html (9,065 bytes)
2. Re: [Amps] SELL: Ameritron AL1200 Contestor's Amplifier (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 00:57:35 -0400; <<Tom -- So why do Eimac's published constant current curves on the tube begin to deviate from a straight line when the anode current exceeds 2.5a peak?>> Odd-order IM distortion is the result of a t; /archives//html/Amps/2006-06/msg00358.html (9,706 bytes)
3. Re: [Amps] SELL: Ameritron AL1200 Contestor's Amplifier (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 02:32:53 -0400; Running a tube at other than the specified tolerances shown on the published curves by the manufacturer can and will void warranties.> Eimac is long QRT on 3-500Z tubes, but they had a rating system; /archives//html/Amps/2006-06/msg00365.html (10,746 bytes)
4. [Amps] IM distortion and such (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 11:10:09 -0400; Richardson's looked at the AL80B manual also. They had no problem with it. They own Amperex. Anyone with a basic understanding of tubes should know a thoriated tungsten's life isn't compromised in t; /archives//html/Amps/2006-06/msg00375.html (14,712 bytes)
5. Re: [Amps] Zener? question.. (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 15:46:31 -0400; Is the amp grounded-grid cathode-driven? Does it have screen and bias supplies? What's the HV? Which way are the diodes pointed? Anode to positive source or cathode towards it? 73 Tom ______________; /archives//html/Amps/2006-06/msg00386.html (7,030 bytes)
6. [Amps] Neutralizing Dentrons (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 16:17:31 -0400; The most difficult to stabilize tubes are generally those with the longest and thinnest element leads. The 811/572 family falls into this category. If you look at older amps like the Heath Warrior an; /archives//html/Amps/2006-06/msg00391.html (7,712 bytes)
7. Re: [Amps] cathode return? (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 17:43:08 -0400; There is no cookie-cutter answer. Depending on filament voltage and other operating/bias voltages, you can get varying amounts of 60 cycle AC on the output. _________________________________________; /archives//html/Amps/2006-06/msg00397.html (7,114 bytes)
8. Re: [Amps] Neutralizing Dentrons (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 17:55:59 -0400; Not for the reasons you gave. 1.) Heath and Gonset did not make any more four parallel tube amps using tubes with high feedthrough capacitance. They had no reason to put it in other amps. 2.) The pa; /archives//html/Amps/2006-06/msg00398.html (7,357 bytes)
9. Re: [Amps] IM distortion and such (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 18:06:29 -0400; I think you are really saying an engineer shouldn't ever design outside what is actually published on a spec sheet that only covers a limited number of situations under any condition, even if the co; /archives//html/Amps/2006-06/msg00399.html (9,950 bytes)
10. Re: [Amps] Neutralizing Dentrons (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 19:39:07 -0400; What four tube amp was that Rich? I can't seem to recall it even though I did various RF designs for Heath. Who at Heath told you they chose not to use it for the reasons you mentioned? ____________; /archives//html/Amps/2006-06/msg00407.html (7,627 bytes)
11. Re: [Amps] Problem with AL-811 (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 25 Jun 2006 22:46:43 -0400; Assuming you are tuning correctly by opening the loading control to reduce grid current and it just ain't working for you..... Change the negative rail protection clamp diode. It is the single diode; /archives//html/Amps/2006-06/msg00417.html (6,937 bytes)
12. Re: [Amps] IM distortion and such (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 26 Jun 2006 06:03:14 -0400; Not when they approve the operating conditions. I think the problem here is this thread, like many on this reflector, has had a major performance change. The original subject was the manual of the A; /archives//html/Amps/2006-06/msg00421.html (8,144 bytes)
13. Re: [Amps] IM distortion and such (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 26 Jun 2006 13:15:59 -0400; What people forget is amateur radio is not an unlimited money customer resource like commercial radio, and the basic use is a lot different. Commercial RF applications have deep pockets, Hams are ch; /archives//html/Amps/2006-06/msg00446.html (11,606 bytes)
14. Re: [Amps] Grid Protection Circuit Ideas (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 26 Jun 2006 13:27:08 -0400; Get a regular manual and you also should get the schematic. I'd just order the PC board from them. It uses an op amp driving a fast relay, and by changing only one resistor value you can set the tog; /archives//html/Amps/2006-06/msg00448.html (7,440 bytes)
15. Re: [Amps] IM distortion and such (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 26 Jun 2006 13:34:55 -0400; 1.) It was already agreed the extra emission demand causes no component life problems. 2.) It can be proven it doesn't make the amp less linear as was initially claimed. Case in point, read the post; /archives//html/Amps/2006-06/msg00449.html (10,146 bytes)
16. Re: [Amps] AL-80B questions (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 26 Jun 2006 15:54:23 -0400; The first question goes to tuning the amplifier. I am using a Vacuum Variable cap, 3 - 30pF on the plate and the original air variable plate cap has been moved to the load position. With 60 watts of; /archives//html/Amps/2006-06/msg00456.html (10,570 bytes)
17. [Amps] Grid protection resistors (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 26 Jun 2006 16:46:57 -0400; By the way, NEVER use a resistor to protect sensitive expensive devices. Fuses are bad enough. They have a very slow failure period as they melt and then open. The time is also dependent on temperatu; /archives//html/Amps/2006-06/msg00467.html (7,143 bytes)
18. Re: [Amps] AL-80B questions (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Mon, 26 Jun 2006 21:44:33 -0400; A doubler with that conduction angle should have well under 10% efficiency, but I suppose it is possible the 6 meter tank is hitting two or more frequencies at once. That was one thing that crossed; /archives//html/Amps/2006-06/msg00481.html (7,895 bytes)
19. Re: [Amps] IM distortion and such (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 27 Jun 2006 05:46:22 -0400; Will, Where did you get the idea 400mA is a "minimum distortion" condition? 73 Tom _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/m; /archives//html/Amps/2006-06/msg00502.html (9,475 bytes)
20. Re: [Amps] Amps Digest, Vol 42, Issue 67 (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 27 Jun 2006 05:52:42 -0400; ....and worse yet for the manufacturer, under coupling results in high voltages in the tank circuit. Besides all that splatter, it decreases reliability of the amp and the life of expensive tank com; /archives//html/Amps/2006-06/msg00503.html (7,203 bytes)

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