Date: Sat, 4 Dec 93 04:30:31 PST From: Ham-Homebrew Mailing List and Newsgroup Errors-To: Ham-Homebrew-Errors@UCSD.Edu Reply-To: Ham-Homebrew@UCSD.Edu Precedence: Bulk Subject: Ham-Homebrew Digest V93 #122 To: Ham-Homebrew Ham-Homebrew Digest Sat, 4 Dec 93 Volume 93 : Issue 122 Today's Topics: MiniSport Laptop Hacker - Vol 17 sw-radio coils...question. Trunk 900Mhz > ham bands??? Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Homebrew Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-homebrew". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: 29 Nov 93 03:41:28 GMT From: ucsnews!sol.ctr.columbia.edu!spool.mu.edu!olivea!isc-br!tau-ceti!comtch!opus-ovh!bmork@network.ucsd.edu Subject: MiniSport Laptop Hacker - Vol 17 To: ham-homebrew@ucsd.edu MiniSport Laptop Hacker - Vol 17, Nov 1993 Copyright (c) 1993 Brian Mork -- "not to make money, but to keep it that way for others, too." >>> ADMIN Remember, you can get copies on disk of any software or text files (in- cluding the MLHacker series) I refer to by sending me a disk and SASE. I'll put a variety of other MLHacker related goodies on there, too. Alternately, contact me using the information in the signature block. Please, contribute! MLHacker is available on the KA6ETB Internet HAM-Server. Send a message to ham-server@grafex.cupertino.ca.us with the single line of text: HELP to get access information. Check the \hamradio\newsletters directory. I'm watching for other Packet or Internet archivers who will host the MLHacker series. >>> POWER SUPPLY A lot of people have a problem where the computer fails to stay powered on. Two LEDs blink for a second or two and then the computer powers down. One of mine has been having this trouble, too, and I finally had a chance to reverse engineer the power supply. The Minisport power supply pinout to the motherboard is via a 16 pin mini scotchflex connector. Pin 1 is indicated by a white arrow on the power supply board. Reverse engineering was carried backward into the power supply only until I was reasonably sure I understood how the circuit was suppose to work. Notice some capacitors seem to be reverse biased. Sur- face mount dielectric capacitors still have the banded end negative, right? Pins 2,5 and 6 are not accounted for yet because of unidentified compo- nents. Pins 5,6, and 10 are the ones with bad voltages either causing my problem or as a result of my problem. What a coincidence, eh? Here's what I've been able to determine. I'm particularly interested in what *your* header voltages are if you have this notorious power-off failure mode. These schematics are not a "sure thing" -- they're determined us- ing visual trace following, an ohmeter, and a diode checker. I'm partic- ularly unsatisfied with the Pin 10 circuitry. Other fixit experts out there, please give me ideas! S487 1004 bobbin "-B" .-->|-->|-.----.--~~~~-.----.----.-->|-.---.------ Pin4 (+5v) ( | | | | | | | ) P11 | | | \-\ | 100| LB| ( H922 | 470| 4.7| - ^6.8 | === === ) xformer | === === |Znr | | | ( | | | + | | | | | / / / | / / | | | .----->|---.----- Pin1 (+5v to only .-- glass diode S487 | 2nd MB RAM) to Pin10 === circuitry |LB | .----- Pin3 (GND) | / A3 bobbin .---------------------------->|---.---~~~---.----- Pin7 (+10v) ( | | ) G923 === === ( P12 | | ) xformer / / ( A3 bobbin .------|<---.---~~~---.--------------------------- Pin8 (-10v) ( | + | | ) G923 === === === ( P12 | 47 - | 3.3 LB | ) xformer / / / ( .-- Pin11,13,14 | | (GND) / 608C04 .--. bobbin | |----.-------~~~-------.----.---------------- Pin15,16 (+5v) .--. | | | .---. 100 | \-\ 1000| | 0.1 === ^ === === | |6.8v | | | | Znr .---. / / | | / edge |14 MB3778 |----- Pin 9 (from computer) | (_stby)| MIDL -----------. center | | | MB3778 |14 +5v(pin4) / 10k (_stby)|------------------ Pin 12 (from computer) | \ | | / | 1 / | 4.7K 0 \ | .-/\/\--. 0 / / variable | | "-B" K \ --\--> resistor | -.--|<- Pin 10 (6.6v when working) / / | / | | 10K | |< BV3 ---->|----.----.------<\ /---/\/\-.---| PNP glass | | \/ |\ diode | \ ---- | from |LB /51K | CBZ2 | Pin4 === \ | NPN +5v(pin4) circuitry | / | | | | .----.--------. | / MIDL is identified in MLH Vol 14 -- in essence, it is +9v power, deliv- ered through a diode. LP stands for "Little Beige capacitor." I'm guessing they're 0.01uf by- pass capacitors. They have no markings. In order to progress further, I need to know the identification of a few parts: "24" - 3pin rectangular SMC, 1/16" x 1/8" "14" - 3pin rectangular SMC, 1/16" x 1/8" "BV3" - 3pin rectangular SMC, 1/16" x 1/8" "CBZ2" - 4tab SMC, looks like fixed volt reg (3 + tab) Please provide feedback: * BBS 1-509-244-9260 * AX.25 KA9SNF@wb7nnf.#spokn.wa.usa 73, Brian * Internet bmork@opus-ovh.spk.wa.us --- Brian Mork Internet bmork@opus-ovh.spk.wa.us . . . . Amateur Radio (AX.25) ka9snf@wb7nnf.#spokn.wa.usa ... . .. USMail 6006-B Eaker, Fairchild, WA 99011 ------------------------------ Date: Thu, 2 Dec 93 14:34:00 GMT From: mnemosyne.cs.du.edu!nyx10!lkollar@uunet.uu.net Subject: sw-radio coils...question. To: ham-homebrew@ucsd.edu A partially-related question -- does Amidon, or any reseller, sell a pre-packaged assortment of the most commonly-used toroids? All these different types are CONFUSING to the homebrewer wanna-be -- and from what I've read here, you can't count on color-coding to keep them straight.... It seems the hardest part of homebrewing these days is figuring out which parts you need then finding them. There's a business opportunity for those who know what they're doing -- it costs more than $5 to start, but you won't go to jail either. :-) P.S. Nobody answered my question about using a magnetron from a micro- wave oven in osc/amp circuits. I'm not asking you to do all the work for me, but pointers to available articles would be appreciated. Thinking about winding my coils on Quaker Oats canisters (just like Grandpa used to!), I am -- -- Larry Kollar, KC4WZK | I like CW, but that doesn't mean I think every ham lkollar@nyx.cs.du.edu | should have to learn it. "On the Internet, nobody knows you're a dog." ------------------------------ Date: 3 Dec 93 22:22:50 GMT From: ogicse!uwm.edu!spool.mu.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!ehsn2.cen.uiuc.edu!ah6542@network.ucsd.edu Subject: Trunk 900Mhz > ham bands??? To: ham-homebrew@ucsd.edu Hello everyone, I had a little question, has anyone ever tuned-down a trunked radio (business bands up in 900MHz) to the ham bands?? A friend of mine recently recieved an old one that had a bad battery pack (but they didn't realize). It is an old Motorola that is very nice on the inside, it is very modular etc. -along w/ dials and things to change stuff w/. Ever hear of this being done??? TNX! et 73's Allen Hall n9rzc@uiuc.edu ps- e-mail appreciated (can't always get to the posts) ------------------------------ Date: 3 Dec 93 14:42:30 GMT From: ogicse!emory!kd4nc!ke4zv!gary@network.ucsd.edu To: ham-homebrew@ucsd.edu References , <2dj0ou$19t@hpuerca.atl.hp.com>, <1993Dec2.143400.16392@mnemosyne.cs.du.edu> Reply-To : gary@ke4zv.atl.ga.us (Gary Coffman) Subject : Re: sw-radio coils...question. In article <1993Dec2.143400.16392@mnemosyne.cs.du.edu> lkollar@nyx10.cs.du.edu (Larry Kollar) writes: > >P.S. Nobody answered my question about using a magnetron from a micro- > wave oven in osc/amp circuits. I'm not asking you to do all the > work for me, but pointers to available articles would be appreciated. There was an article in 73 Magazine a year or so back about a fellow who was injection locking a microwave oven magnetron to act as a high power FM FSTV transmitter. Like an automotive battery charger, the PS in microwave ovens is deceptively simple. The transformer is made intentionally lossy, and operated near saturation, in order to provide protection for the tube in case of flashover or poor cavity SWR due to things like using metal in the oven. It's also only halfwave rectified and poorly, if at all, filtered. You have to build a fairly sophisticated HV supply if you want clean signals while protecting the tube from transient overcurrent. That's the toughest part of using magnetrons. Gary -- Gary Coffman KE4ZV | Where my job's going, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | I don't know. It might | uunet!rsiatl!ke4zv!gary 534 Shannon Way | wind up in Mexico. | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | -NAFTA Blues | ------------------------------ End of Ham-Homebrew Digest V93 #122 ****************************** ******************************