Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: power supply  (Read 357 times)
N8YAC
Member

Posts: 2




Ignore
« on: June 16, 2006, 08:01:18 AM »

would like to know if anyone can help me out by letting me know where I can get info to build power supply
from computer PS plaese let me know ASAP
Logged
WA4BLM
Member

Posts: 2




Ignore
« Reply #1 on: June 16, 2006, 10:23:09 AM »

Check out this link:

http://www.arrl.org/members-only/tis/info/pdf/0205035.pdf

You'll probably have to be an ARRL member to see it.  If not, it's from the May 2002 QST if you can find it.

John WA4BLM
Logged
W3LK
Member

Posts: 5639




Ignore
« Reply #2 on: June 16, 2006, 12:32:05 PM »

There have been several threads on this subject over the past few years. You can find them using the search function of eHam.

The general concensus seems to be the project isn't worth the effort except for QRP usage.

73,

Lon - W3LK
Baltimore, Maryland
Logged

A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
AB9LZ
Member

Posts: 198




Ignore
« Reply #3 on: June 16, 2006, 12:53:14 PM »

>>The general concensus seems to be the project isn't worth the effort except for QRP usage.<<

Having done a bit of my own research, I'll second and third that. Oh, some of them even make bad QRP supplies due to the harmonics showing up in all of the wrong places.

73 Mark.
Logged
WA9SVD
Member

Posts: 2198




Ignore
« Reply #4 on: June 16, 2006, 01:22:03 PM »

It's generally not a good solution.  The majority of supplies leave out (or jumper) the critical filter components that SHOULD be included, to reduce cost, leading to a lot of potential (and real) interference.  And you have to provide a minimum load to the 5 Volt portion to even get the supply to start up.  THAT's power wasted.  The power you can take from the +12 V. portion is only a fraction of the total power the supply can provide;  the supplies are designed for maximum power to the 5 V. bus, not through the 12 V. bus.  And 12 V. is all it should provide, +/- 10% or so.  You will NOT get the 13.8 Volts most radios like, even if they will work with 12 V.  Also, voltage regulation is determined by the 5 V. circuitry, so load variations on the 12 Volt side could be quite substantial.
    And that's just for an old "AT" style power supply.  If you want to use an "ATX" supply, the problems getting it to work are increased by a magnitude.

    All in all, considering the trouble involved, it's not really worth it.

    YES, there was an article in QST a few years back.  But there was also a published rebuttal to that article (by WB2WIK/6) that stressed the drawbacks and problems associated with using "computer" switching supplies for Amateur Radio use.  At least read that, not just the original QST article, if you can.
Logged
KE4DRN
Member

Posts: 3722




Ignore
« Reply #5 on: June 16, 2006, 02:03:11 PM »

hi,

http://www.antennex.com/preview/archive3/powers.htm

Please be aware that there are lethal voltages inside
these switching power supplies.

Not sure of how many watts you need but keep an eye
out for used Astron power supplies here and on ebay,
if you locate one close to your qth the ship fees will
be lower

Another choice would be a Lambda Vega or Alpha used
power supply, they turn up all the time at low cost.


73 james
Logged
K1CJS
Member

Posts: 6034




Ignore
« Reply #6 on: June 16, 2006, 02:17:21 PM »

I agree, you have to get hold of the right supply, but if you get a high capacity (400-500 watt) supply, this little cheapie project will work.  I've gotten a 400 watt supply, wired a wire wound resistor (47 ohms, if I remember) onto the 5 volt section and have gotten fifteen amps out of the 12 volt section before adjusting the supply to get move voltage from it.  I ended up with about 13.4 volts at 12 amps from my $20 investment.

Since this is a rebuilding/reconfiguring project, it is meant more as an educational project than a practical, everyday use project.  It can be done BUT (you just had to know that was coming) I would not recommend such a supply as the primary supply for a radio.  I use it with a standby VHF rig, there isn't any noise problems to speak of, and it isn't used every day.  Mind you, I wouldn't use this supply with a HF rig except to just listen to the bands, but it works fine powering a 40 watt VHF rig for both transmitting and receiving.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!