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141. Re: [Amps] HF-2000 amp problem? (score: 1): Author: TexasRF@aol.com; Date: Sat, 14 Apr 2007 12:28:14 EDT; Sounds like you need to increase the drive to 50-75w like 20m and load heavier (less load C) for maximum output. If this scares you, load heavier first and then increase the drive power. 73, Gerald K; /archives//html/Amps/2007-04/msg00120.html (7,627 bytes)
142. Re: [Amps] HF-2000 amp problem? (score: 1): Author: TexasRF@aol.com; Date: Mon, 16 Apr 2007 10:56:37 EDT; Hi Jim, heavier loading causes more cathode current to flow to the plate and less to the grid. Heavier loading implies that the plate load impedance is lower and there will be more plate current flow; /archives//html/Amps/2007-04/msg00167.html (10,339 bytes)
143. Re: [Amps] Flash over in 3-500Z tspa (score: 1): Author: TexasRF@aol.com; Date: Mon, 23 Apr 2007 15:24:31 EDT; John I have wondered how an ion pumps works. What does it do, where connected and polarity? I have seen that they are usually rated for only a few milliamperes typically so apparently there is not a; /archives//html/Amps/2007-04/msg00237.html (10,639 bytes)
144. Re: [Amps] Triode vs Tetrode Amp (score: 1): Author: TexasRF@aol.com; Date: Thu, 26 Apr 2007 12:52:50 EDT; Hi Keith, many, if not most, engineering decisions are $$ based. A source of cheap 4CX800 tubes from Russia could cause a company to use them instead of expensive 3CX800 tubes in an amplifier design; /archives//html/Amps/2007-04/msg00319.html (7,692 bytes)
145. Re: [Amps] W6PO 2m amp (score: 1): Author: TexasRF@aol.com; Date: Wed, 9 May 2007 19:14:04 EDT; Sounds like a classic case of low drive power. That tube typically has a gain of around 14 dB with plate voltage that low. If the cathode bias is set to a level higher than optimum, the gain could be; /archives//html/Amps/2007-05/msg00093.html (8,714 bytes)
146. [Amps] 1296 QRO (score: 1): Author: TexasRF@aol.com; Date: Sat, 26 May 2007 11:34:06 EDT; Carl, Bob and others, depending on your definition of QRO, there are several options for power today: drive to about 400w output, designed by KD5FZX and in use by many ops and documented at www.nd2x.; /archives//html/Amps/2007-05/msg00217.html (11,324 bytes)
147. Re: [Amps] AL-80B transformer tap (score: 1): Author: TexasRF@aol.com; Date: Tue, 24 Jul 2007 10:49:04 EDT; I have not followed this discussion as closely as others so please excuse me for restating any obvious facts. When you select the 250vac tap on the Ameritron transformer, you are not generating volta; /archives//html/Amps/2007-07/msg00403.html (9,482 bytes)
148. Re: [Amps] Gassy Tubes/Technology Museum looking for artifacts (score: 1): Author: TexasRF@aol.com; Date: Thu, 26 Jul 2007 11:02:42 EDT; Wild guess: to prevent plugging a 6.3v filament tube in a 12.6v socket? Maybe 807's were also used in other applications in that era. Remember the early 1625 "linear" amplifier designs requiring a ho; /archives//html/Amps/2007-07/msg00437.html (8,236 bytes)
149. Re: [Amps] Gassy Tubes/Technology Museum looking for artifacts (score: 1): Author: TexasRF@aol.com; Date: Thu, 26 Jul 2007 16:35:59 EDT; Have you ever measured the frequency stability of one of those old Command set/ARC 5 transmitters? I did many years ago and the stability was just phenomenally excellent. No wonder some of the early; /archives//html/Amps/2007-07/msg00445.html (13,128 bytes)
150. Re: [Amps] crossmodulation in PA ? (score: 1): Author: TexasRF@aol.com; Date: Wed, 5 Sep 2007 09:03:54 EDT; Nils, don't overlook the possibility that the cross modulation is taking place in the feed line, antenna, an unused antenna, the guy system or tower. Any corroded/less than zero ohm joint has the pos; /archives//html/Amps/2007-09/msg00024.html (9,828 bytes)
151. Re: [Amps] TL-922A (score: 1): Author: TexasRF@aol.com; Date: Fri, 14 Sep 2007 10:34:58 EDT; Back in the mid 80's I ran a TL922 while "playing" at contesting. I say playing because my contesting skills are too poor to really compete. Even in the play mode on SSB after a couple of hours of st; /archives//html/Amps/2007-09/msg00145.html (7,618 bytes)
152. Re: [Amps] Ameritron AL-1200 (score: 1): Author: TexasRF@aol.com; Date: Tue, 30 Oct 2007 15:45:14 EDT; Sounds like eight new capacitors and eight new bleeder resistors would take care of the immediate problem. After multiple failures there is a likelihood that the remaining capacitors have been stress; /archives//html/Amps/2007-10/msg00275.html (9,999 bytes)
153. Re: [Amps] 2 Tubes in Parrallel: (score: 1): Author: TexasRF@aol.com; Date: Fri, 9 Nov 2007 10:31:30 EST; Bruce, your 1300 ohm figure is right on the money. The three Ameritron amplifiers you mention run similar plate currents so the plate load Z will also be similar. The loaded Q might vary a bit from u; /archives//html/Amps/2007-11/msg00125.html (8,002 bytes)
154. Re: [Amps] 6N075T, unobtainium? (score: 1): Author: TexasRF@aol.com; Date: Thu, 13 Dec 2007 10:11:35 EST; Marc, this # is listed in RF Parts catalog. You might give them a call at 800 RF PARTS. 73, Gerald K5GW In a message dated 12/12/2007 8:24:38 P.M. Central Standard Time, marcchicoine@bellsouth.net wr; /archives//html/Amps/2007-12/msg00151.html (7,611 bytes)
155. Re: [Amps] VHF amplifier input network (score: 1): Author: TexasRF@aol.com; Date: Thu, 20 Dec 2007 10:51:29 EST; The combination L1/C1 does NOT resonate at the operating frequency. The two components create a virtual inductance that becomes the series input arm of an L network that cascades with a second L netw; /archives//html/Amps/2007-12/msg00182.html (8,958 bytes)
156. Re: [Amps] HV Supplies and Diodes (score: 1): Author: TexasRF@aol.com; Date: Wed, 2 Jan 2008 17:49:45 EST; I find it a bit strange and somewhat comical that the only ones that appear to champion resistors and capacitors across any series string of 1N540x diodes is the amateur community. Not one manufactur; /archives//html/Amps/2008-01/msg00020.html (9,428 bytes)
157. Re: [Amps] questions about hi pot tester (score: 1): Author: TexasRF@aol.com; Date: Thu, 3 Jan 2008 16:09:15 EST; One useful source of high voltage parts is from old microwave ovens. In particular, the power transformer, filter capacitors and diodes are plentiful and cheap on Ebay. The filter caps are typically; /archives//html/Amps/2008-01/msg00042.html (10,777 bytes)
158. Re: [Amps] Oil-caps delating 2/3 ratings? (score: 1): Author: TexasRF@aol.com; Date: Thu, 6 Mar 2008 11:48:12 EST; Han, I have lost two similar capacitors running at about 3500vdc over the years. Both of my capacitors were purchased from Peter Dahl Co and were rated for 5000vdc working voltage. I came to the conc; /archives//html/Amps/2008-03/msg00048.html (8,017 bytes)
159. Re: [Amps] UK Transformer manufacturer?? (score: 1): Author: TexasRF@aol.com; Date: Fri, 14 Mar 2008 11:15:00 EDT; I know this is a British expression; but is a "cracker" a good thing or bad thing? 73, Gerald K5GW In a message dated 3/14/2008 1:28:09 A.M. Central Standard Time, john@carltonhouse.eclipse.co.uk wri; /archives//html/Amps/2008-03/msg00120.html (8,771 bytes)
160. Re: [Amps] Grid Bias Supply followup (score: 1): Author: TexasRF@aol.com; Date: Sat, 22 Mar 2008 09:53:59 EDT; Perhaps the -100vdc is used for cutoff bias in receive? A typical t/r circuit might use a set of relay contacts to lift the + end of the rheostat from ground on receive thus allowing the full -100vdc; /archives//html/Amps/2008-03/msg00205.html (7,771 bytes)

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