# VK200 r.f choke maximum current

Discussion in 'General Electronics Discussion' started by tzitzikas, May 20, 2010.

1. ### tzitzikas

16
0
May 9, 2010
i have a linear amplifier which is using VK200 r.f choke (at input voltage). I would like to ask you which is the maximum current? Because when i operate the linear (7A current) the VK200 r.f choke is very very warm. thank you

2. ### davennModerator

13,866
1,958
Sep 5, 2009
I'm not suprised it gets hot !! doing some research on that choke tells me its a small 6 hole ferrite bead with relatively fine wire through it ~ 25 SWG its good for an amp or 2
maybe 3amps at the extreme. You need a considerably larger ferrite core and much heavier gauge wire for a ~7A current.

an example .... look at the chokes on the high current +5 and +12V outputs on a
computer PSU board. Rat one off a dead PSU ... if its an HF transmitter amplifier ... one of those chokes would probably do the trick. For VHF or UHF a few less turns through
the ferritr core

Dave
VK2TDN

3. ### tzitzikas

16
0
May 9, 2010
hi. i am thinking to replace the vk200 choke with some turns of wire, on ferrite bead.
i have some pieces of this ferrite bead: FB-43-7351 from amidon (43 material)
look here: https://www.amidoncorp.com/items/44
how many turns i must use to have the same inductance with the vk200. i don't know how to calculate the number of turns, and also i don't know the vk200's inductance.
(the circuit is an mw band (600-1800khz) linear amplifier),
and the maximum current is 15A.

If i use 4 vk200 (in parallel ) i will use the same inductance or 1/4 inductance, It will work?

Last edited: May 21, 2010
4. ### davennModerator

13,866
1,958
Sep 5, 2009
they dont look as tho you can get a thick wire through them let alone a number of turns

look again at the suggestion in my first posting those chokes have the current handling
capability you need, as well as the sort of inductances needed at Low HF freqs.
the other things you are wanting to try DONT have the current capabilities forget them

Dave