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241. [AMPS] Gound fault (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Fri, 10 Aug 2001 08:30:28 -0400; The last thing in the world anyone should do with an HF amplifier is use an RF sensing system to switch the thing! Timing problems are bad enough without waiting until RF appears to transfer the amp; /archives//html/Amps/2001-08/msg00117.html (7,386 bytes)
242. [AMPS] Tetrode poor IMD performance (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 15 Aug 2001 17:39:02 -0400; Hi All, Does anyone have any idea why tetrode amps like the one just reviewed in QST seem to have such poor IMD performance? Is it the tube, the circuitry, or a testing error? I mean, -29dB ala ARRL; /archives//html/Amps/2001-08/msg00141.html (7,459 bytes)
243. [AMPS] 4CX800 Filament Voltage ? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 16 Aug 2001 21:26:51 -0400; In amateur service, virtually zero tube failures come from filament hours. Most come from excessive grid currents or just plain old flawed tubes. With an indirectly heated tube, you can actually rui; /archives//html/Amps/2001-08/msg00172.html (7,468 bytes)
244. [AMPS] 14KW (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 16 Aug 2001 21:39:58 -0400; When we work DX with QRP the OTHER GUY should get the award and pat on the back, not the QRP guy. He is the poor $#% who has to have a good system and skills, not the weak signal guy. He is doing al; /archives//html/Amps/2001-08/msg00173.html (8,866 bytes)
245. [AMPS] QRP (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Fri, 17 Aug 2001 10:02:40 -0400; Hi Phil, That's certainly fine Phil. But the operating skill is mainly at the end doing the receiving, not the transmitting. All the transmitting station has to do is press the key at the correct tim; /archives//html/Amps/2001-08/msg00190.html (9,430 bytes)
246. [AMPS] Tube going bad? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sun, 19 Aug 2001 14:08:08 -0400; It is not necessarily at tube problem, especially if you can drive the PA to normal output when it is acting acting up.It is certainly not gassing, because that causes a HV anode to grid/cathode fla; /archives//html/Amps/2001-08/msg00226.html (8,252 bytes)
247. [AMPS] 572B and an old FL2000B (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Tue, 21 Aug 2001 09:01:31 -0400; The power gain of the Svetlana 572 is not higher, the problem is the cut-off bias requirement is higher. In amplifier that are not neutralized, this can cause the tubes to oscillate when the amplifi; /archives//html/Amps/2001-08/msg00258.html (9,308 bytes)
248. [AMPS] RJ-iAvacuum relay (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Tue, 21 Aug 2001 09:32:09 -0400; To add insult to injury, many used or surplus parts actually are being sold for more than the parts cost brand-new! 73, Tom W8JI W8JI@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps; /archives//html/Amps/2001-08/msg00261.html (7,755 bytes)
249. [AMPS] 572B and an old FL2000B (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 22 Aug 2001 07:52:31 -0400; Not true in the least Paul. A layout has to be extremely poor to require neutralization, but many tubes have so much anode/cathode feedthrough they require neutralization no matter what the layout.; /archives//html/Amps/2001-08/msg00278.html (8,899 bytes)
250. [AMPS] 572B and an old FL2000B (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 22 Aug 2001 15:24:12 -0400; No, I didn't. The best socket is one that grounds the grid pins with zero lead length, but the problem is rooted in the internal construction of the tube....not the socket. The way you correct it is; /archives//html/Amps/2001-08/msg00293.html (8,637 bytes)
251. [AMPS] Tetrode poor IMD performance (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 22 Aug 2001 15:24:12 -0400; That's pure 100% nonsense. Current limiting actually INCREASES IMD when you hit the limit. The only plus is it save the tube from damage! Voltage regulation is what reduces splatter, not current reg; /archives//html/Amps/2001-08/msg00294.html (8,827 bytes)
252. [AMPS] Harris Receivers (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 22 Aug 2001 22:10:33 -0400; This is a bit off topic, but I'm looking for three or four used/surplus Harris RF590 or 590A receivers. I know of a surplus outlet that sells them in Toronto, but they are a bit expensive. 73, Tom W8; /archives//html/Amps/2001-08/msg00299.html (6,525 bytes)
253. [AMPS] CTI ComTEC, Inc. (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 23 Aug 2001 17:48:29 -0400; Actually 4CX250's are among the poorest tubes for IMD. Was you amp ever type accepted? What is the TA number? I did an FCC database search, and couldn't find it. You know of course any amplifier of; /archives//html/Amps/2001-08/msg00304.html (9,276 bytes)
254. [AMPS] CTI ComTEC, Inc. (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Fri, 24 Aug 2001 05:51:54 -0400; Cathode driven tubes are for the most part extremely linear, especially when driving impedance is high and grid currents low. The inherent negative feedback and loading of the exciter reduces or eli; /archives//html/Amps/2001-08/msg00310.html (9,451 bytes)
255. [AMPS] CTI ComTEC, Inc. (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Fri, 24 Aug 2001 11:52:53 -0400; That really doesn't mean anything. I find a grantee code of PHD issued for CTI Comtec, but a search of PHD in the FCC database at http://www.fcc.gov/oet/fccid/ shows no TA or other FCC authorization; /archives//html/Amps/2001-08/msg00317.html (7,924 bytes)
256. [AMPS] Glitch protection relay (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 29 Aug 2001 13:35:29 -0400; Most HV faults are caused by gas in the tube. It is doubtful parasitics are behind any of them. If the tube and other components have enough HV breakdown to operate at the desired frequency, they alm; /archives//html/Amps/2001-08/msg00365.html (8,566 bytes)
257. [AMPS] Tuned input (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Mon, 9 Jul 2001 22:12:40 -0400; There is a fourth reason. Efficiency is more predictable because the input, which is rich in harmonics, can be bypassed to ground at harmonics. This ensures decent efficiency when the network is des; /archives//html/Amps/2001-07/msg00123.html (8,037 bytes)
258. [AMPS] Tuned Input Circuit Board (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 11 Jul 2001 10:33:11 -0400; Amp supply and Dentron always had trouble with DIP relay failures in the ten meter position of that board when used for heavy CW use, like contesting. This was especially true with tubes having a lo; /archives//html/Amps/2001-07/msg00146.html (7,765 bytes)
259. [AMPS] Tuned Input Circuit Board (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 12 Jul 2001 20:21:23 -0400; What is the part number of those relays? I'm testing some relays for an RF switch application this week. 73, Tom W8JI W8JI@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submission; /archives//html/Amps/2001-07/msg00159.html (7,502 bytes)
260. [AMPS] close ratings (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Tue, 17 Jul 2001 12:12:32 -0400; Hi John, That is true only for a properly loaded amplifier. In a misloaded or mistuned PA,. or a greatly over-driven PA, the peak RF voltage can greatly exceed the supply voltage on each half of the; /archives//html/Amps/2001-07/msg00197.html (8,306 bytes)

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