Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
Ohmite Resistance in the Information Age




 
The AM Forum
October 21, 2017, 09:42:05 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Ohmite Resistance in the Information Age  (Read 455 times)
0 Members and 1 Guest are viewing this topic.
KB2WIG
Contributing
Member
*
Offline Offline

Posts: 4040



« on: March 14, 2017, 11:29:22 PM »



I've got a dummy load that is composed of (5)   OHMITE Non-Inductive  Vitreous Enameled Resistor Stock No. 2208. They are marked at 250 ohms.  Google is not my friend. None of my old catalogs, the current Ohmite online search engine or even the Google has any information fer me.

Watt I want to know is, What are these things rated for dissipation?  They are about 6 1/2 inches long........  My conservative guess is 100 watts.

Any help would be appreciated?

klc
Logged

What? Me worry?
N0WEK
Contributing
Member
*
Offline Offline

Posts: 752



« Reply #1 on: March 14, 2017, 11:42:18 PM »



I've got a dummy load that is composed of (5)   OHMITE Non-Inductive  Vitreous Enameled Resistor Stock No. 2208. They are marked at 250 ohms.  Google is not my friend. None of my old catalogs, the current Ohmite online search engine or even the Google has any information fer me.

Watt I want to know is, What are these things rated for dissipation?  They are about 6 1/2 inches long........  My conservative guess is 100 watts.

Any help would be appreciated?

klc

Well you could put 125 volts to the load which would give you about 312 watts, about 63 watts each, and see how quick they get hot. That will give you some idea of how far and how long you can push them.

Greg


Logged

Diesel boats and tube gear forever!
KA2DZT
Member

Offline Offline

Posts: 1967


« Reply #2 on: March 15, 2017, 12:04:29 AM »

They are 100  watters.  I have a number of them, I'll take a look and get back.

I'm back,  took me a half hour to find my Ohmite catalog.  

Ohmite #2208 are 100 watters 250ohms.  They are useful throughout the BC band and higher frequencies depending on what resistance is being used.  The description doesn't add anything else as to what resistances are usable at higher frequencies.  Inductance is suppose to be less than 1% of that of regular power resistors.  The RF resistance is suppose to be the same as the DC resistance throughout the useful frequency range.

Very low distributed capacity and the change in impedance is suppose to be very slight throughout the useful frequency range.

Description adds that these resistors are use for dummy antennas (loads), antenna terminating resistors and used in diathermy equipment.

Should be mounted with non-magnetic brackets.

Hope this helps

Fred
Logged
WD5JKO
Member

Offline Offline

Posts: 1653


WD5JKO


« Reply #3 on: March 15, 2017, 07:17:13 AM »



Hey Fred, any chance that there is a photo in that Ohmite catalog of the "Ohmite Girl"? I've heard that years back, she would show up at trade shows wearing a color coded outfit.

Jim
Wd5JKO
Logged
KB2WIG
Contributing
Member
*
Offline Offline

Posts: 4040



« Reply #4 on: March 15, 2017, 12:29:22 PM »


Thank EVERYONE .....  thats watt I wanted. So I've got a nice 500W dummy load. I vonder if adding a muffin fan would boost the dissipation..

KLC
Logged

What? Me worry?
KA2DZT
Member

Offline Offline

Posts: 1967


« Reply #5 on: March 15, 2017, 12:44:39 PM »

Add a fan to increase the dissipation BUT those resistors should never be loaded to the full rating.  Maybe 250-300 watts with the fan for short periods.

Fred
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.082 seconds with 18 queries.