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Total 306 documents matching your query.

281. [Amps] Looking for Big P-band Amplifier (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Thu, 05 Jan 2012 09:56:05 -0800
At my work, we are looking to rent or buy a high power (4 to 6KW peak) amplifier that operates in the 280 to 440 MHz range or some subset of that range (preferably the high end). The amplifier can be
/archives//html/Amps/2012-01/msg00065.html (7,128 bytes)

282. Re: [Amps] Grid current protection HELP (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Mon, 13 Feb 2012 18:14:53 -0800
I don't see how the opto-isolator triggers anything. According to the schematic it switches 100K to ground on a node fed by the output of a 7815 regulator. That doesn't make any sense to me. I think
/archives//html/Amps/2012-02/msg00132.html (9,701 bytes)

283. Re: [Amps] Grid current protection HELP (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Mon, 13 Feb 2012 20:15:43 -0800
That would make more sense, Al. There is also the issue with figure 2 in the article (the reflected power protection interface). It shows the output of the comparator going to pin4 of the 555 timer,
/archives//html/Amps/2012-02/msg00142.html (12,346 bytes)

284. Re: [Amps] question for you experts... (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Wed, 28 Mar 2012 14:30:08 -0700
What you say makes sense, Gary, especially when you consider that the PI-network caps are usually air dielectric and the plate block capacitor is usually some sort of ceramic doorknob. If the blockin
/archives//html/Amps/2012-03/msg00322.html (16,166 bytes)

285. Re: [Amps] Overdrive protection (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Fri, 27 Jul 2012 06:13:23 -0700
With an extra SO-239 on the rear panel and a coax jumper, the amp manufacturer could provide a "loop-thru" for an external power attenuator. This would allow the user to tailor the drive requirements
/archives//html/Amps/2012-07/msg00295.html (9,617 bytes)

286. Re: [Amps] Overdrive protection (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Fri, 27 Jul 2012 06:36:31 -0700
Oh, duh, I should have said two extra SO-239s, otherwise you couldn't insert the attenuator after the input T/R relay. Mike W4EF................. _______________________________________________ Amps
/archives//html/Amps/2012-07/msg00296.html (9,384 bytes)

287. Re: [Amps] Overdrive protection (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Fri, 27 Jul 2012 07:51:55 -0700
Jim, The issue isn't so much lack of discipline as it is the power overshoot of the internal ALC circuits found in many modern solid-state transceivers. Yes, a disciplined operator can dial back the
/archives//html/Amps/2012-07/msg00304.html (10,459 bytes)

288. Re: [Amps] current threads about silver solder and resoldering (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Tue, 28 Aug 2012 15:17:15 -0700
In my experience high-rel IC pins are often passivated with a thin layer of gold plating. Gold and tin-lead solder are a bad combination (Indium solder and gold is even worse) due to the poor charact
/archives//html/Amps/2012-08/msg00515.html (12,418 bytes)

289. [Amps] Alpha 87A in Remote Station Service (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Wed, 08 May 2013 18:45:11 -0700
I am in the process of trying to set up a remotely controlled HF station. I am looking at amplifiers selection and was wondering if anyone out there has had experience they could share about using th
/archives//html/Amps/2013-05/msg00124.html (6,682 bytes)

290. Re: [Amps] Participate in NASA experiment (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Mon, 07 Oct 2013 15:56:32 -0700
I think this question is kind of mute now with the government shut down. Do they stop the spacecraft in their orbits while the government remains shut down? I fear that will be kind of hard to do! :
/archives//html/Amps/2013-10/msg00113.html (9,978 bytes)

291. Re: [Amps] MOVs (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Sun, 26 Jan 2014 14:57:49 -0800
Jim, This is probably a dumb question, but why not put the MOV between hot and neutral? If the spike is differential mode, that would kill it without spiking current into the safety ground. 73 Mike W
/archives//html/Amps/2014-01/msg00251.html (9,641 bytes)

292. Re: [Amps] L4-B (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Mon, 31 Mar 2014 18:01:59 -0700
It is used pretty extensively in the flight hardware that JPL builds for space. I know for a fact there was a bunch used on the landing radar for the Curiosity rover. I am sure there is a bunch of it
/archives//html/Amps/2014-03/msg00201.html (10,755 bytes)

293. Re: [Amps] Impressive solid-state 1.5 kW amp (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Sat, 27 Feb 2016 12:03:09 -0800
Yes, from just their webpage it does look kind of like vaporware, except for the IMD test data (which, by the way, looks decent as SSPAs go): http://www.dedicatedrf.com/imd.html There are some pictur
/archives//html/Amps/2016-02/msg00070.html (9,525 bytes)

294. Re: [Amps] Remote control of Alpha 9500 (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Thu, 9 May 2019 17:05:29 -0700
Yeah, there are all kinds of interesting gadgets out there for this sort of thing nowadays. Last year I needed to go a ~150 feet with HDMI video from a laptop up to a projector for a performance I wa
/archives//html/Amps/2019-05/msg00021.html (9,326 bytes)

295. [Amps] Alpha 87A Problem (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Sun, 26 May 2019 10:55:07 -0700
My Alpha 87A had been working  pretty faithfully up until the end of March / early April. I haven't used it since then until this weekend. Normally I operate remotely, but this weekend I had to come
/archives//html/Amps/2019-05/msg00067.html (8,023 bytes)

296. Re: [Amps] Alpha 87A Problem (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Mon, 3 Jun 2019 12:46:47 -0700
Thank you to everyone who replied for your thoughtful suggestions. I hope to have some time to troubleshoot the amplifier this coming weekend. I'll try to pass on what I discover. 73 Mike, W4EF On 5/
/archives//html/Amps/2019-06/msg00012.html (8,484 bytes)

297. Re: [Amps] Alpha 9500 questions (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Sun, 26 Jul 2020 14:33:16 -0700
FWIW, if you go to the "about" tab on the Alpha RF Systems webpage, there is a link at the bottom to a job advertisement for a repair technician:         https://www.alpharfsystems.com/?page_id=1534
/archives//html/Amps/2020-07/msg00024.html (10,796 bytes)

298. [Amps] SB-221 Power Gain (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Fri, 31 Jul 2020 23:01:35 -0700
I have an old SB-221 donated from the estate of the original builder. I think it was assembled in 1981. With 100 Watts of drive and the HV switch in the SSB position (stiff 240V service), I am gettin
/archives//html/Amps/2020-08/msg00000.html (7,328 bytes)

299. Re: [Amps] SB-221 Power Gain (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Sun, 2 Aug 2020 19:51:39 -0700
Thanks to everyone who responded to my questions. The consensus of the responses is that the numbers I am getting are typical for an SB-221 with 100 watts drive. I agree with those who suggested that
/archives//html/Amps/2020-08/msg00014.html (9,242 bytes)

300. [Amps] Signs of Life at Alpha RF Systems (score: 1)
Author: Michael Tope <W4EF@dellroy.com>
Date: Thu, 20 Jan 2022 13:50:50 -0800
I check the Alpha RF Systems website every few months for any signs of life. It looks like there is finally some good news: https://www.alpharfsystems.com/?p=3640 73, Mike W4EF................ ______
/archives//html/Amps/2022-01/msg00055.html (6,581 bytes)

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