[Amps] SB 220 Exploding Resistor

[George]

Hi Carl,
Your right I looked up the momentary overload and it is only 1.5 times 
the rated power.
73, George
W2GS

On 1/20/2016 4:49 PM, Carl wrote:
> And how well does it hand a surge manybe 10X its rating?
> Not very well I'll guarantee
>
> Carl
> KM1H
>
>
>
> ----- Original Message ----- From: "George" <at6c at bellsouth.net>
> To: <amps at contesting.com>
> Sent: Tuesday, January 19, 2016 10:33 AM
> Subject: Re: [Amps] SB 220 Exploding Resistor
>
>
>> John,
>> Have you ever looked at Surface Mount Power Film Resistors?  A 25 
>> ohm/ 25 watt is available from Mouser at around $6.  I used one of 
>> these as the input resistor on a tetrode amp several years ago and it 
>> has work without any issues.
>>
>> http://www.mouser.com/ds/2/62/MP725-2439.pdf
>>
>> 73, George
>> W2GS
>>
>> On 1/18/2016 3:13 PM, John Lyles wrote:
>>> If you get a strong enough wirewound resistor, this can suffice as 
>>> the surge current limiting resistor for a spark over in a tube. With 
>>> 250 amps at the beginning of the overcurrent (2500 V/10 ohms) spike, 
>>> there is enough magnetic field to break a wirewound R as the 
>>> windings have mechanical force between turns. I have always used 
>>> bulk carbon for series R, like Kanthal Globar makes. They are 
>>> exactly the right part for this.
>>>
>>> http://www.globar.com/ec/bulk-ceramic-resistors/globar-bulk-ceramic-non-inductive-resistor-applications.html 
>>>
>>>
>>> http://www.globar.com/ec/bulk-ceramic-resistors/axial-leaded-resistors.html 
>>>
>>>
>>> Finding them through distribution might be a problem, though. Has 
>>> anyone else used these?
>>>
>>> John
>>> K5PRO
>>>
>>>
>>>> Date: Sun, 17 Jan 2016 13:19:20 -0500
>>>> From: "Carl" <km1h at jeremy.qozzy.com>
>>>> To: "Tom Hellem" <tom.hellem at gmail.com>, <Amps at contesting.com>
>>>> That blown resistor may have been underated and blew during a tube 
>>>> arc. The
>>>> idea of a surge suppressor is to not fail and allow the 
>>>> milliseconds for a
>>>> fuse/breaker to open.
>>>> A 10-15 Ohm 20-25W Real wirewound resistor will cure that problem. 
>>>> Look for
>>>> Vitreous Enamel in the description.
>>>> Carl
>>>> KM1H
>>>
>>>
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>>>
>>
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