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201. [Amps] filament instant heating query (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Fri, 15 Jun 2012 13:12:36 -0600
The mechanical expansion of a cold filament is the function that weakens them. I suppose this means molecular level... Some examples: As Jim Thompson said, thoriated tungsten cold R is much lower tha
/archives//html/Amps/2012-06/msg00157.html (11,513 bytes)

202. [Amps] tube fils..again (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sat, 16 Jun 2012 14:42:33 -0600
Some large power tetrodes and triodes require DC due to the risk of vibration of the large filaments at 120 Hz. AC filaments are pleasant to deal with as usually a center tap on the filament transfor
/archives//html/Amps/2012-06/msg00214.html (10,925 bytes)

203. [Amps] tubes without handles (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Thu, 21 Jun 2012 07:05:23 -0600
Correction: Preamps PS, for good tube books, don't forget any of the texts by Fredrick Terman. And the best online source for classic tube books, for free download, is Peter Millets DIY Audio book pa
/archives//html/Amps/2012-06/msg00326.html (7,752 bytes)

204. [Amps] 1.5 KW 8877 at 100 MHz (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sat, 14 Jul 2012 15:29:17 -0600
As part of a trade for a medium wave BC transmitter that I recycled, I received a large package via UPS last evening. Inside was a Broadcast Electronics FM1.5A power amplifier drawer. The sticker sai
/archives//html/Amps/2012-07/msg00196.html (8,254 bytes)

205. [Amps] Jennings Vacuum Variables (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Thu, 26 Jul 2012 13:13:10 -0600
I don't know of an online resource right now, but I have older catalogs for Jennings and Comet Capacitors, if you shoot me a part number I will send you a PDF of the page. 73 John K5PRO ** __________
/archives//html/Amps/2012-07/msg00278.html (7,791 bytes)

206. [Amps] Dedicated RF (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sun, 29 Jul 2012 23:01:58 -0600
3CX800s were used in a number of Henry Amplifiers sold for ISM service, VHF and UHF. I know of several that have been used to drive superconducting resonators and particle bunchers for scientific app
/archives//html/Amps/2012-07/msg00391.html (11,512 bytes)

207. [Amps] CPI Inc absorbed Freeland rebuilding service (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Mon, 30 Jul 2012 11:39:27 -0600
CPI Econco Division Acquires Freeland Products WOODLAND, Calif. - February 13, 2012 - The Econco Division of Communications & Power Industries LLC (CPI) has acquired the business of Freeland Products
/archives//html/Amps/2012-07/msg00423.html (8,963 bytes)

208. [Amps] 3CX1500A7 pulled from MRI (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Wed, 1 Aug 2012 15:16:07 -0600
I am curious - do MRI still use tubes or are they mostly solid state power-amplified now? Most of the elemental analysis (still-called NMR) use VHF SS PAs. I like the 8877/3CX1500A7. Its a great trio
/archives//html/Amps/2012-08/msg00021.html (9,970 bytes)

209. [Amps] 4CX1500B (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Thu, 9 Aug 2012 13:00:31 -0600
Me too! I have these tubes, sockets and filament transformers, wishing for time now to build a nice amplifier. Thanks at least for inspiration. 73 John K5PRO _________________________________________
/archives//html/Amps/2012-08/msg00157.html (7,068 bytes)

210. [Amps] 87a will tell you, too - measuring overshoot (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Wed, 15 Aug 2012 19:43:11 -0600
I'm a big fan of Tektronix scopes. Have been through my share, including 465, various 7603,23,33 etc. Problems with the old ones include non-obtainium ICs as well as difficulty in repairing them, due
/archives//html/Amps/2012-08/msg00235.html (8,732 bytes)

211. [Amps] Parasitics Resistor Value (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Fri, 17 Aug 2012 17:12:18 -0600
Amen, for the Measurements GDO. Although I have gotten more and more used to using Network analyzer to SEE strange resonances, but its a low Z instrument. Remember the teen ham book SOS at Midnight?
/archives//html/Amps/2012-08/msg00289.html (7,504 bytes)

212. [Amps] RF insulating materials - engineered plastics (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Tue, 28 Aug 2012 00:40:48 -0600
I just finished a series of comparison tests of a handful of polymeric materials and blends, for use in high power VHF amplifier projects. I didn't test Nylon, Delrin acetal, Polyethylene or Polyprop
/archives//html/Amps/2012-08/msg00496.html (9,212 bytes)

213. Re: [Amps] RF insulating materials - engineered plastics (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Tue, 28 Aug 2012 13:26:24 -0600
David, you are correct, should be 200 mA for the starting plate current for that column. I have used a 3D printed plastic part as an air shroud around the screen contact ring on the TH628, operating
/archives//html/Amps/2012-08/msg00509.html (11,587 bytes)

214. Re: [Amps] RF insulating materials - engineered plastics (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Tue, 28 Aug 2012 13:32:13 -0600
Dave It would be nice to have the time and a wide variety of materials to do this. Everyone seems to have a pet material for RF insulators. I did the measurements for materials i use on my job. All w
/archives//html/Amps/2012-08/msg00510.html (9,153 bytes)

215. [Amps] RF insulating materials - engineered plastics (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Tue, 28 Aug 2012 13:53:45 -0600
Several things could explain what is described: 1) The RF oscillator in the preheater is free-running. It is affected by the dielectric in the air capacitor zone. In addition, it is coupled such that
/archives//html/Amps/2012-08/msg00511.html (9,821 bytes)

216. [Amps] SOURCE OF TURNS COUNTER(S) - US SUPPLIERS (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Mon, 10 Sep 2012 22:46:55 -0600
I've got some catching up to do, been on the road to the midwest US and back, ~ 3500 miles of driving. Here is one other source of turns counter dials in the USA: http://www.kintronic.com/products/pr
/archives//html/Amps/2012-09/msg00189.html (9,122 bytes)

217. [Amps] 32 Volt LDMOS being superceded by 50 V? (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Tue, 11 Sep 2012 17:39:46 -0600
No they are not. MRF151G is still popular especially, several sources. They are also used in many broadcast television amplifiers, so they won't be gone soon. In new designs, choose 50 V and use a 48
/archives//html/Amps/2012-09/msg00236.html (8,317 bytes)

218. [Amps] CPI/EImac reducing app engineering (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Thu, 20 Sep 2012 19:08:28 -0600
Yes, I wonder the same thing. Reid sent me an email Monday saying he was given notice, that they no longer have application engineer for power grid tubes. I have known him for over 25 years and have
/archives//html/Amps/2012-09/msg00262.html (8,909 bytes)

219. [Amps] HFS-3000D (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Thu, 20 Sep 2012 19:16:24 -0600
Today I found a CCA (later PlasmaTherm and RF Plasma Products) HFS-3000D for $75 in a local surplus hole. It is missing the tube (5CX1500?) and was rated 3 kW on 13.56 MHz. The AC is three phase and
/archives//html/Amps/2012-09/msg00263.html (6,572 bytes)

220. [Amps] Using small relays at RF (score: 1)
Author: "John Lyles" <jtml@losalamos.com>
Date: Tue, 30 Oct 2012 13:18:48 -0700
W0QE has put together a nice set of measurements that are beneficial to all amplifier builders, thanks for the work there. 73 John K5PRO _______________________________________________ Amps mailing l
/archives//html/Amps/2012-10/msg00219.html (7,279 bytes)

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