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321. [Amps] 3CX1500A7/8877 (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sun, 12 Feb 2017 23:25:34 -0700
Around 1980-84, I was an RF engineer on a team that built a series of new FM broadcast transmitters in Quincy, Illinois. All were tetrode designs using the newest tubes with handles from Eimac at the
/archives//html/Amps/2017-02/msg00077.html (12,242 bytes)

322. Re: [Amps] 3CX1500A7/8877 (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Mon, 13 Feb 2017 23:06:41 -0700
Hi Jeff, Yes, I was there after the first transmitter was built, which was the largest, the 30 kW. I started from the lower power end and designed the cavity amplifiers and transmitters from 3.5 kW u
/archives//html/Amps/2017-02/msg00086.html (9,790 bytes)

323. [Amps] PowerGenius XL - Others (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Tue, 14 Feb 2017 00:07:14 -0700
I've been using water cooled pulsed RF amplifiers since 1995 at work. The first uses were DMOS MRF151G variants running @28 VDC. In the last 3 years we have moved those out and gone to 48 volt LDMOS,
/archives//html/Amps/2017-02/msg00087.html (10,905 bytes)

324. [Amps] Checking Filament Voltage (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sun, 19 Feb 2017 22:55:47 -0700
This is probably a bad idea, for tubes over a few hundred watts power rating. Most ceramic metal tubes require cooling under the base, and for a few minutes, might still overheat the cathode/heater.
/archives//html/Amps/2017-02/msg00148.html (7,879 bytes)

325. [Amps] SS amps watercooling - was PowerGenius XL (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Mon, 20 Feb 2017 19:37:31 -0700
Continuing this thread, we used deionized/deoxygenated water for our RF power tubes at the accelerator plant. I designed the anode cooling tubing to have no more than 500 uA of leakage current per ho
/archives//html/Amps/2017-02/msg00157.html (9,152 bytes)

326. [Amps] SS amps watercooling - was PowerGenius XL (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Wed, 22 Feb 2017 23:58:28 -0700
I use 7 Altronic 200 kW loads. I visited the factory in Arkansas two years ago. Very nice stuff. We always put the flow switch/sensor in the outlet side of a system, where it returns to the pump or g
/archives//html/Amps/2017-02/msg00180.html (8,416 bytes)

327. [Amps] WATERCOOLING AMPLIFIERS (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Mon, 6 Mar 2017 12:20:00 -0700
Jeff, WN3A's experience with glycol mixes and cooling power amplifiers is normal for systems that need to be both corrosion inhibited and also can be freeze-proof. In our RF plant, we use both high p
/archives//html/Amps/2017-03/msg00055.html (8,123 bytes)

328. [Amps] WATERCOOLING TUBES (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Fri, 10 Mar 2017 14:54:47 -0700
Eimac has an app note for water and vapor cooling, which is similar to RCA/Burle/Photonis and Thompson/Thales, Amperex/Philips, E2V, Siemens, Telefunken recomendations. All refer to using DI water (o
/archives//html/Amps/2017-03/msg00088.html (10,588 bytes)

329. Re: [Amps] Price per Watt Conversation (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sun, 23 Apr 2017 15:41:55 -0600
There has been excellent discussion here about the new LDMOS devices and their potential use for HF amplifiers. Manfred (XQ6FOD), Karl-Arne (VK5KLT) and Leigh (VE7RF) have each made strong points abo
/archives//html/Amps/2017-04/msg00228.html (13,091 bytes)

330. Re: [Amps] MRF151G Vs VRF2933 (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Wed, 3 May 2017 01:34:16 -0600
The MRF151G is a push pull 'gemini' packaged part. MACOM sells their equivalent on Mouser's website for about $105 in 10 piece qty. This part has been around for decades and is very well known and us
/archives//html/Amps/2017-05/msg00042.html (7,617 bytes)

331. [Amps] LDMOS and DMOS RF MOSFETs (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Thu, 4 May 2017 01:24:30 -0600
This was on line, dated 2014. An interesting perspective on LDMOS and plain DMOS transistors. 73 John K5PRO -- Reports of the Death of DMOS RF MOSFETs are Greatly Exaggerated by Mark Vitellaro, Direc
/archives//html/Amps/2017-05/msg00048.html (14,880 bytes)

332. [Amps] HV MOSFETs for RF (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Fri, 5 May 2017 10:46:53 -0600
Its been really interesting reading comments on this subject. Up to now, most of the innovation posted on line has been using nonlinear classes like E for homebrew AM transmitters (another topic!) an
/archives//html/Amps/2017-05/msg00066.html (7,585 bytes)

333. [Amps] HV MOSFETs for RF (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Mon, 8 May 2017 01:44:12 -0600
Hi Cathy, For particle accelerator RF systems, we require linearity for some systems where the envelope of the RF pulse has ramped voltages. This is needed to capture particles such as ions and proto
/archives//html/Amps/2017-05/msg00092.html (9,030 bytes)

334. [Amps] Ten-Tec Titan 10 Meter Input SWR (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Mon, 12 Jun 2017 00:03:41 -0600
Hi Gerald, You can use a Delta Electronics OIB2 HF Operating Impedance Bridge to measure the input Z under power. Would need a constant carrier level for the meter to null easily. 73 John K5PRO Date:
/archives//html/Amps/2017-06/msg00183.html (9,035 bytes)

335. [Amps] Machlett 3-500z (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sat, 22 Jul 2017 13:11:24 -0600
One thing is known for certain, Machlett is only the name and not the original company. They have long been out of business and Eimac bought their assets and product line over a decade ago. Machlett
/archives//html/Amps/2017-07/msg00084.html (8,454 bytes)

336. [Amps] ratings for caps for filters, for SSPA (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sun, 20 Aug 2017 15:36:48 -0600
Another source of high Q low ESR ceramic RF power chip capacitors besides American Technical Ceramics: http://www.passiveplus.com/index.php I haven't priced them, though, they look expensive but very
/archives//html/Amps/2017-08/msg00040.html (8,738 bytes)

337. [Amps] Hard bus bar copper and inductor Q (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sat, 2 Sep 2017 01:51:24 -0600
PA5Y, In my opinion, either material would work fine for your amplifier. Keeping interturn capacitance low isn't a big issue with so few turns for a 50 Mhz PA. With the copper tubing, you can always
/archives//html/Amps/2017-09/msg00001.html (10,491 bytes)

338. [Amps] Plate coupling capacitor value (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Thu, 7 Sep 2017 23:24:19 -0600
The capacitive reactance Xc of the plate DC blocking ppcapacitor should be chosen so that on the lowest frequency it has a low value of ohms. This way it doesn't have a significant RF voltage across
/archives//html/Amps/2017-09/msg00040.html (8,192 bytes)

339. [Amps] Glitch resistor + fuse? (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Wed, 15 Nov 2017 23:40:06 -0700
Maybe someone already covered this, but I stay away from using wirewound resistors for series energy limiters in tube power amplifiers. For one thing, when you are dumping 50 amps or more for a few u
/archives//html/Amps/2017-11/msg00158.html (8,537 bytes)

340. Re: [Amps] Glitch resistor + fuse? (score: 1)
Author: John Lyles <jtml@losalamos.com>
Date: Sun, 19 Nov 2017 23:35:57 -0700
In very high power amplifiers for pulsed RF service, I use active crowbars. With 15-25 kV plate voltages, I use triggered mercury Ignitrons. Right now we are evaluating a stack of big thyristors, 85
/archives//html/Amps/2017-11/msg00172.html (12,823 bytes)

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