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201. Re: [Amps] 4CX1600U - too good to be true? (score: 1): Author: TexasRF@aol.com; Date: Wed, 26 Aug 2009 18:36:52 EDT; Bill if you decide to persue using this tube, it is also known as a GS23B. There is complete tube data as well as amplifier designs for the tube at _www.nd2x.net/index.html_ (http://www.nd2x.net/inde; /archives//html/Amps/2009-08/msg00516.html (9,091 bytes)
202. Re: [Amps] RF parts and parasitics!! (score: 1): Author: TexasRF@aol.com; Date: Wed, 26 Aug 2009 21:52:16 EDT; When the grid is grounded for cathode driven operation is there a difference between cathode to grid impedance and cathode to ground impedance? Doesn't seem there would be. 73, K5GW In a message date; /archives//html/Amps/2009-08/msg00528.html (8,659 bytes)
203. Re: [Amps] Tube gain vs frequency (score: 1): Author: TexasRF@aol.com; Date: Wed, 26 Aug 2009 23:56:33 EDT; Regarding current flow from the anode to the top cap connection: RF will flow on the surface of conductors. All of the rf then has to pass through the ceramic to metal seal. The amount of rf flowing; /archives//html/Amps/2009-08/msg00535.html (11,571 bytes)
204. Re: [Amps] Not the Diacrode (score: 1): Author: TexasRF@aol.com; Date: Fri, 28 Aug 2009 12:20:19 EDT; I lost a couple of good TH347 tubes due excess filament current at turn on. I thought there was sufficient turn on current limiting but apparently not. A circuit was devised from readily available pa; /archives//html/Amps/2009-08/msg00579.html (9,430 bytes)
205. Re: [Amps] TH347 filament ramping (score: 1): Author: TexasRF@aol.com; Date: Fri, 28 Aug 2009 17:33:18 EDT; Fortunately one was used and the other was a rebuilt tube. The filament went open like a bad light bulb when they failed. The price of rebuilt tubes has doubled over the past few years. They were aro; /archives//html/Amps/2009-08/msg00584.html (8,210 bytes)
206. Re: [Amps] TH347 filament ramping (score: 1): Author: TexasRF@aol.com; Date: Fri, 28 Aug 2009 18:17:15 EDT; Carl, that was a price quoted by Freeland Products, a tube rebuilder in the New Orleans LA area. New tubes were around $6K from Richardson Electronics the last time I checked. There will be no new TH; /archives//html/Amps/2009-08/msg00587.html (10,863 bytes)
207. Re: [Amps] Ug2 stabilization in TMN linear amp (score: 1): Author: TexasRF@aol.com; Date: Fri, 4 Sep 2009 10:37:25 EDT; Peter, there is usually a hefty bleeder resistor on the output of this type G2 power supply. The bleeder resistor tends to stabilize the G2 voltage. The LC filter circuit is inherently more stable th; /archives//html/Amps/2009-09/msg00041.html (8,132 bytes)
208. Re: [Amps] SB221 Low Power Help (score: 1): Author: TexasRF@aol.com; Date: Tue, 8 Sep 2009 13:21:53 EDT; If you have a small antenna tuner, it can be used to reduce the vswr for test purposes. 73, Gerald K5GW In a message dated 9/8/2009 11:59:00 A.M. Central Daylight Time, vu3raz@gmail.com writes: I wil; /archives//html/Amps/2009-09/msg00098.html (10,289 bytes)
209. Re: [Amps] SB221 Low Power Help (score: 1): Author: TexasRF@aol.com; Date: Tue, 8 Sep 2009 13:47:33 EDT; Rahul, You can't use the internal tuner because the amplifier input impedance varies with drive level and the auto tuner tries to follow that. It is too slow for that kind of use. The radio senses th; /archives//html/Amps/2009-09/msg00101.html (11,910 bytes)
210. Re: [Amps] LK500-ZB (score: 1): Author: TexasRF@aol.com; Date: Wed, 9 Sep 2009 14:54:17 EDT; Has anyone tried to blow a grid to cathode short with a high current pulse of energy? Such as touching the shorted pins for an instant with a car battery. At this point seems not much to loose by try; /archives//html/Amps/2009-09/msg00127.html (7,977 bytes)
211. Re: [Amps] 76ca (score: 1): Author: TexasRF@aol.com; Date: Wed, 9 Sep 2009 15:40:56 EDT; As a wild guess (have not been there/done that), the inductance of the suppressor is too high. There will be a voltage drop across that inductance related to the current through it. If this voltage i; /archives//html/Amps/2009-09/msg00131.html (7,981 bytes)
212. Re: [Amps] LK500-ZB (score: 1): Author: TexasRF@aol.com; Date: Wed, 9 Sep 2009 18:15:21 EDT; I understand that! So, you just keep the tube until it is the last one? Or, sell it to a CB'er on Ebay? 73, Gerald K5GW In a message dated 9/9/2009 5:15:34 P.M. Central Daylight Time, vk6apk@bigpond.; /archives//html/Amps/2009-09/msg00134.html (9,585 bytes)
213. Re: [Amps] LK500-ZB (score: 1): Author: TexasRF@aol.com; Date: Fri, 11 Sep 2009 12:44:44 EDT; It seems there could be a risk of excess filament current if the "wrong" filament pin is selected. To minimize the risk of this, both filament pins can be connected together and the "zapper" connects; /archives//html/Amps/2009-09/msg00153.html (8,359 bytes)
214. Re: [Amps] Query about capacitor value (score: 1): Author: TexasRF@aol.com; Date: Tue, 15 Sep 2009 13:57:25 EDT; Back about 20 years ago Peter Dahl was selling those NWL 53 uF 5KVDC oil filter capacitors for large $$. I purchased two of them for 4kv power supplies to use with 8877 amplifiers. Both capacitors ex; /archives//html/Amps/2009-09/msg00203.html (9,199 bytes)
215. Re: [Amps] Vacuum variable hipotting (score: 1): Author: TexasRF@aol.com; Date: Fri, 18 Sep 2009 18:31:31 EDT; John, perhaps you can shed some light on how bad can a vacuum leak be before the tube is unusable. I have seen some used tubes that begin to show current with as little as 1600 volts between the anod; /archives//html/Amps/2009-09/msg00245.html (8,831 bytes)
216. Re: [Amps] Vernier dials, have one but... (score: 1): Author: TexasRF@aol.com; Date: Sun, 4 Oct 2009 09:18:24 EDT; The rich kids ordered the Space Spanner with band switch. Us poor boys had to order the Ocean Hopper and a new plug in coil as we could find the $$ to order. Ah! The good old days! 73, Gerald K5GW In; /archives//html/Amps/2009-10/msg00056.html (9,945 bytes)
217. Re: [Amps] Need bushing (score: 1): Author: TexasRF@aol.com; Date: Mon, 5 Oct 2009 22:22:21 EDT; If you have a drill press and vise, you can make one in a few minutes. A one inch section of a .75" bolt makes the donor material. Drill through the center .25" and then drill again half way .375" di; /archives//html/Amps/2009-10/msg00122.html (7,741 bytes)
218. Re: [Amps] B- questions (score: 1): Author: TexasRF@aol.com; Date: Mon, 9 Nov 2009 11:46:44 EST; Some rough ballpark numbers: If there is a 25 ohm glitch resistor and an instantaneous short from B+ to ground, there could be a maximum current of 3000/25 or 120 amps. If the meter circuit was 1 ohm; /archives//html/Amps/2009-11/msg00141.html (11,923 bytes)
219. Re: [Amps] FW: B- questions (score: 1): Author: TexasRF@aol.com; Date: Tue, 10 Nov 2009 21:35:46 EST; Doug, I don't think that no one here knows anything about Ameritron amplifiers as much as no one here has the schematic diagram memorized to the point of knowing where D16 is located in the circuit.; /archives//html/Amps/2009-11/msg00168.html (9,230 bytes)
220. Re: [Amps] trying to understand 1296 cavity amp (score: 1): Author: TexasRF@aol.com; Date: Fri, 20 Nov 2009 13:41:37 EST; Gary, Without getting too deep into cavity theory, the rf is generated between the plate and grid in that tube. The rf flows on the cavity inner surfaces only. The rf will not pass through any of the; /archives//html/Amps/2009-11/msg00210.html (8,943 bytes)

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