A new thing to worry about

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The Daring Dufas wrote:

That would be hard to do at HF or VHF since you can't focus the RF into a tight beam at those frequencies, compared to a couple degrees or less at microwave frequencies. :)

If you must, but I just like to trade war stories about equipment that would make newbie techs retch or fill their drawers when they see the size and the hazards involved. The sheer look of terror on their faces is priceless! Like me standing on the HV power supply inside a VHF high band TV transmitter so I can adjust the interstage coupling while the station is on the air. The end of the cabinet was removed, since it didn't have any interlocks, and i was standing on one of the transformers. It was either do it that way, or spend days removing the rear door, making a small adjustment, replacing the rear door then firing it up to find it still had too much ripple in the video bandwidth, shutting it down and starting over. :)
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Michael A. Terrell wrote:

I've worked with a lot of high voltage power but there on the island the highest power runs were 4160 3 phase. The superintendent I was working with borrowed a wooden hot stick from the power plant crew. Lucky thing he was wearing the high voltage glove set. I think his hard hat popped off when his hair stood on end while we were plugging in the transformers. Did you know that a slightly damp hot stick will conduct electricity? Ya know shortcuts can be dangerous. This particular guy got himself killed a few years later when he fell down a shaft in Cairo while trying to change a lamp in a fixture on a big sewer project. He decided he didn't need that pesky safety harness.
As far as that big radar goes, I know I wasn't hearing things. It will operate in CW mode at VHF and UHF frequencies. Here's a link and I still wish I had gotten a closer look at that thing.
http://www.smdc.army.mil/KWAJ/RangeInst/ALTAIR.html
TDD
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The Daring Dufas wrote:

RADAR works by timing the reflections. They are using 'CW' to imply that there is no complex modulation.
Have you ever read the 'RADAR Handbook' by Merrill I. Skolnik? It's big, over 1500 pages & boring, but covers the history & technology of RADAR. :)
Here is an early edition: <http://cgi.ebay.com/Skolnik-Radar-Handbook-microwave-theory-engineering_W0QQitemZ370297236087QQcmdZViewItemQQptZUS_Nonfiction_Book?hash=item56376f6a77
Here is a copy of the new, third edition. <http://cgi.ebay.com/Radar-Handbook-by-Merrill-Ivan-Skolnik-2008-Hardco_W0QQitemZ170418984214QQcmdZViewItemQQptZUS_Nonfiction_Book?hash=item27adc35516
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Michael A. Terrell wrote:

<http://cgi.ebay.com/Skolnik-Radar-Handbook-microwave-theory-engineering_W0QQitemZ370297236087QQcmdZViewItemQQptZUS_Nonfiction_Book?hash=item56376f6a77
<http://cgi.ebay.com/Radar-Handbook-by-Merrill-Ivan-Skolnik-2008-Hardco_W0QQitemZ170418984214QQcmdZViewItemQQptZUS_Nonfiction_Book?hash=item27adc35516
Oh come on, I know how RADAR works, I even own my own low power X-band Doppler unit. It's a blast to play with. I won't even pretend to know how that huge SOB ALTAIR works. The site mentions in the specifications "Modulation: CW and Linear FM Chirp" What do you make of that? Two different modes or a combination? Darn it, I wish I had asked more about it but a lot of the information was classified so I don't know how much I could have learned. There were guys wandering around out there who could make you feel like am amoeba because they were so much smarter. They all seemed to come from those alphabet universities. *snicker*
TDD
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The Daring Dufas wrote:

'FM Chirp' is a side effect of pulse modulation of some transmitter tubes.
Those 1500+ pages go into a lot of details that you might find interesting. :)
My MOS was broadcast engineer, but I did spend some time repairing Korean War era RADAR systems at Ft. Rucker. I really pissed of the RADAR tech I was assigned to work with. he would spend a half hour hauling everything from the truck to the RADAR site while I went in with a Simpson 260 and the manual. I would diagnose the problems before he was finished hauling everything the quarter mile walk between were we were allowed to park, and the base of the antennas. He got even madder when I told him the only training that I had was studying the W.W.II aircraft RADAR manuals in my high school's physics lab. The final blow was when I told him that RADAR was a stripped down TV set with no sound. :)
I bet those guys would have been lost looking at the 40+ 'D' sized schematics for the DSP based Microdyne RCB2000 dual telemetry receiver & digital combiner if they were still alive in 2000. Rf was down converted to a 70 MHz IF center frequency, and sampled from 50 to 90 MHz. Then the data was processed through FIR filters. A standard 70 MHz analog IF was created after the IF filter to allow the data to be recorded on standard instrumentation recorders. 70 MHz IF is a holdover from RADAR and early sat IF systems. It was also used in land based telcom microwave relays.
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On Wed, 16 Dec 2009 08:34:29 -0500, Stormin Mormon wrote:

I hate soldering surface-mount stuff by hand, though - and doing those kinds of repair only works when it's not some unobtainable custom part that's failed.
Personally I'd much rather electronic stuff was twice the size (like it used to be), but at least easy to fix - but I'm in a minority there and most folk want stuff as small as possible and who gives a crap when it breaks as they can just buy a whole new one... :-(
cheers
Jules
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The Daring Dufas wrote:

The same with me. I have a lot of trouble sleeping any set schedule, so there is no way that I could work full time. I keep busy repairing computers to give away, do a little free consulting and tech support for a business owned by some friends. Anything to keep busy. :)

That is where I would have burnt the files to a disk before letting them get near it again. :(
I was talking about fixing a TV transmitter, having never seen the inside of one before. Hell, the only thing I had ever done at a TV station before that was be on a kiddy TV show while I was in Elementary school. :)
I read a couple thousand pages of equipment manuals for the equipment at that station, starting the first night on duty. After that, I knew the basic configuration by heart when I had the first failure. :)

I was used to the older techs destroying things because their training was 20+ years out of date.

The VA gave up on my health about five years ago, when they granted 100% disability 14 days after I had to file.
The two local electronics vocational courses were dropped several years ago. The only people who express an interest in electronics don't want to learn to solder, or any math so there isn't much that you can teach them. They think that a couple hours of being shown how to use a meter is all they really need to become experts.
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On Sat, 12 Dec 2009 21:39:20 -0600, The Daring Dufas wrote:

I wish you still had pictures, too - I used to do a lot of exploration / photography in old military places like that, but it's rare to find one where it hasn't been stripped of equipment. Sounds like an interesting place...
cheers
Jules
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Jules wrote:

I had a few souvenirs from the dump and one of them was an iron core memory module that was small enough to fit in a missile. I think I lost it in a move. Darn it, it was a cool item.
TDD
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I can imagine that. Thanks for sharing.
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You funny! (Funny because there is a LOT of truth in what you write.)
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Christopher A. Young
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On Wed, 09 Dec 2009 02:23:44 -0500, mm wrote:

:-) The PSU for our house alarm lives in an outlet on the underside of the basement stairs - to secure it they backed off the outlet cover screw a little and then tied it in place....
Why the person who installed the outlet didn't put it on the side of the stairs, I don't know - it's not like there isn't plenty of room.
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Jules wrote:

Maybe they didn't want it where things could be dropped on it? Or the power cord on their grow light was too short?
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