[Amps] Solid state relays..again

[TexasRF at aol.com]

Surge limiter. usually installed in one leg of the AC line  connection. 
When cold, have high resistance. When hot, low resistance. So,  they run warm 
to hot when in use. You would not want them to be located in a  stream of 
cooling air as that could spoil the low R characteristic.
 
Very interesting and useful device. I use them to limit turn on filament  
current in large transmitting tubes. 
 
Available through Mouser and other distributors.
 
73,
Gerald K5GW
 
 
 
In a message dated 2/13/2014 10:15:13 A.M. Pacific Standard Time,  
bcarling at cfl.rr.com writes:

The  little black varistor thingies work quite nicely for eliminating that  
"THUMMMPP!" in small to medium-size equipment.

I don't really know what  they are but somebody gave me a whole bunch of 
them a while back. I have two  or three different sizes.

Best regards - Bry  Carling



> On Feb 13, 2014, at 10:08 AM, Jim W7RY  <w7ry at centurytel.net> wrote:
> 
> That's why I put step  start in my large Astron power supplies. No more 
thump. No more blown up power  switches.
> 
> 73
> Jim W7RY
> 
>> On  2/13/2014 4:01 AM, Ken Durand wrote:
>> " And this, my dear friends,  is why equipment with steel boxes and big
>> transformers inside can  make that "WHummpppp" at the moment it's 
switched
>> on.
>>  
>> Of course, in equipment controlled by a simple mechanical power  switch, 
it's
>> impossible to decide when exactly in the cycle the  switch will close. 
It's
>> this a lottery how close we will get to  the peak voltage point, or the 
zero
>> crossing. That's why sometimes  the "WHummpppp" is strong, sometimes 
weaker,
>> and sometimes even  non-existent."
>> 
>> Thanks for that bit of wisdom Manfred.  I never could figure out why
>> sometimes I get the "WHummpppp" and  other times the sound would be quite
>> different or non-existent  like you described.
>> 
>> Ken
>> N4zed
>>  
>> -----Original Message-----
>> From: Amps  [mailto:amps-bounces at contesting.com] On Behalf Of Manfred
>>  Mornhinweg
>> Sent: Wednesday, February 12, 2014 12:56 PM
>>  To: amps at contesting.com
>> Subject: Re: [Amps] Solid state  relays..again
>> 
>> Hello,
>> 
>>>  Once in a while that thing turns on with a WHummpppp and a low
>>>  frequency ringing that just trails off.
>> Let's see if I can explain  this in a way everyone can  understand.
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