[AMPS] SB-1000 mods?

[2]

>
>Hi Rich,
>
>Would there be any concern about the lower maximum resistance 
>dictated by the use of
>the 5 watt steady-state rating versus using a 20 or 50 watt resistor? At  
>750mA 

//  The power supply is not able to do 750mA continuous.  Average 
duty-cycle on SSB is c. 15% - CW is c. 30%.


>worst case steady-state anode current, the maximum resistance that 
>could beused with the 5 watt resistor would be ~9 ohms
>, 
//   The lowest value made is 10-ohms.

>whereas at 20 watt resistor could be set as 
>high as 36 ohms
>assuming the same steady state anode current. Seems like the smaller 
>resistor would allow
>the charge in the filter caps to dump much faster than the larger 
>resistor, 

//  A faster dump means more peak current.


>or are there other factors that dominate the discharge time (capacitor 
>ESR, stray inductance, etc). 

ESR adds perhaps a few ohms. 
>
cheers, Mike
>
>----- Original Message ----- 
>From: "2" <2@vc.net>
>To: "Mike" <W4EF@dellroy.com>; "@AMPS" <amps@contesting.com>
>Sent: Sunday, September 09, 2001 4:11 PM
>Subject: Re: [AMPS] SB-1000 mods?
>
>
>> >
>> >Looks like the RCD resistors will do the trick (the 20W parts should
>> >fit nicely in the space available inside the L-7 PS). ... ... ....
>> >
>> Their 5Watter (140 watt-seconds/joules) will do an L-7 with ease 
>> since stored energy is c. 80-joules.   If you get a price, please post it.  
>> cheers, Mike.
>> 
>> >----- Original Message ----- 
>> >From: "Tom Rauch" <w8ji@akorn.net>
>> >To: <amps@contesting.com>; "Mike" <W4EF@dellroy.com>
>> >Sent: Saturday, September 08, 2001 12:35 PM
>> >Subject: Re: [AMPS] SB-1000 mods?
>> >
>> >
>> >> > glitch resistor? I have some 25 ohm/25 watt Dale RER type
>> >> > metal body resistors, but I am concerned that they might be
>> >> > due to the relatively small gap between the leads and the metal
 >>>>> prone to flash over case.
>> >> > Presumeably a ceramic body wire wound resistor is the way to go.
>> >> >  Should I be concerned about inductance (L*di/dt kick) - some
>> >> > wirewounds seem to be classified as "non-inductive" whereas some
>> >> > aren't?
>> >> 
>> >> The resistor must be surge rated for the voltage across the resistor 
>> >> and the peak energy.
>> >> 
>> >> RCD makes xxx-P series pulse rated resistors, or you can use a 
>> >> "glow-bar" type. The RCD pulse rated resistor barely costs more 
>> >> than a conventional wire wound resistor.
>> >> 
>> >> It makes no difference at all if it is inductive, because the 
>> >> inductance will be negligible. Many non-inductive wire wound 
>> >> resistors have a lower than normal voltage rating (from lead to 
>> >> lead), because of the winding method.
>> >> 
>> >> The metal case resistor won't work well.
>> >> 
>> >> 
>> >> 
>> >>   
>> >> 
>> >> 73, Tom W8JI
>> >> W8JI@contesting.com
>> >
>> >
>> >--
>> >FAQ on WWW:               http://www.contesting.com/FAQ/amps
>> >Submissions:              amps@contesting.com
>> >Administrative requests:  amps-REQUEST@contesting.com
>> >Problems:                 owner-amps@contesting.com
>> >
>> >
>> 
>> 
>> -  R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.  
>> end
>> 
>
>
>--
>FAQ on WWW:               http://www.contesting.com/FAQ/amps
>Submissions:              amps@contesting.com
>Administrative requests:  amps-REQUEST@contesting.com
>Problems:                 owner-amps@contesting.com
>
>


-  R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.  
end


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