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: your input  (Read 484 times)
N2JXN
Member

Posts: 189




Ignore
« on: November 24, 2007, 05:26:37 AM »

Hello I just breadboarded a power supply fo a 6 meter amp I am building. The amp uses a set mrf137 transistors which are 24 volts device. The reason for these is that I had them in the junk box. Well I had to also build a 24 volt supply at 3 amp.

The question is I built the power supply around a lm317T variable voltage regulator. and 2 2n3055 pass transistors because I want to be able to use the power supply for a variable voltage suppy. I do not see a problem with this but just wanted to ask if anybody has any input

Thanks
Logged
K8AG
Member

Posts: 352




Ignore
« Reply #1 on: November 27, 2007, 10:31:36 AM »

Not too bad, but if the amp transistors are 24V devices, running 24V power may result in destroyed amp transistors due to overvoltage.

Be sure to use some low value resistors in the emitters of the 2n3055s.  The forward bias voltage drop can vary quite a bit even with transistors from the same batch.  This can cause one transistor to carry the bulk of the current.  With the emitter resistors (~0.2ohm should work), the voltage drops will equalize and current will be distributed through all of the transistors.

My 2 cents.

73, JP, K8AG
Logged
N2JXN
Member

Posts: 189




Ignore
« Reply #2 on: November 30, 2007, 02:38:37 AM »

Thanks for the reply.I put a .1 ohm 10 watt resistor on the emitters. Thanks again for the reply
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!