[Boatanchors] NTC devices for inrush current limiting

[GGLL]

jeremy-ca wrote:
> 
> ----- Original Message ----- From: "Rodger" <wq9e at dtnspeed.net>
> To: <Boatanchors at mailman.qth.net>
> Cc: "Hallicrafters List" <hallicrafters at mailman.qth.net>
> Sent: Wednesday, February 13, 2008 3:10 PM
> Subject: Re: [Hallicrafters] Re: [Boatanchors]Replacing 
> recttubeswithdiodesquestion
> 
> 
> 
>>
>> The NTC inrush limiters I use have a fairly high cold resistance which 
>> drops quickly as they warm up due to current draw.  The ramp up in 
>> voltage can be easily measured.
> 
> 
> As I stated, they operate at the zero crossing and provide minimal 
> protection. In a high power amp they provide even less protection. 
> Granted, something is better than nothing.

	Carl, those NTC devices are linear resistors. They're only aware of 
their own temperature, not phase. They are  very useful in limiting 
inrush currents when they're cold; the main disadvantage is, if you turn 
off the equipment and don't let cool enough the ntc (to allow its own 
resistance rise again), it would not serve as intended. I've used them 
in many transceivers with success.
You may see them used also at the mains input (or rectifier output at 
times) of switching power supplies.

With best regards
Guillermo - LU8EYW.
> 
>