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[AMPS] SB-1000 mods?

To: <>
Subject: [AMPS] SB-1000 mods?
From: (2)
Date: Mon, 10 Sep 2001 09:28:20 -0700
>2 wrote:
>>>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.
>The real limitation for this application is power dissipation in normal
>operation. For say a 30 ohm resistance, 5W size clearly won't handle
>even 0.5A.
//  Ohm's Law:   P=I^2 x R  = 0.5A x 0.5A x 10-ohms = 2.5W.  On SSB 
duty-cycle is around 30%, so avg. dissipation should be c. 2w.  5-second 
dissipation for a PCN5 is rated at 50 watts.  

>Dissipation is downrated drastically with ambient temperature, so the
>10W size would be marginal

//  So, when operating from a (hopefully temporary) DXpdition to Hell,  
(AG6K/HE11) I need to go with a beefier glitch R?    

>   - but possibly OK for an amp that is not
>rated for continuous service. If your design philosophy is "key-down
>forever" in a big amp, you'd go for 50W. So 20W will be about right for
>most people.
// The L-7's HV-PS is patently not "key-down".  

>In any case, the glitch resistor is one of those components that needs
>to be located in a cooling air stream.
>Any idea how to get hold of these resistors in small quantities  at
>reasonable prices? Now it's Monday, is somebody gonna call RCD?
//  To get a reasonable price on the WW glass-coated resistor we use in 
our parasitic suppressor retrofit-kits, we buy 250 units minimum.  For 
Rsup, we buy a box of 1000.
cheers, Ian

-  R. L. Measures, 805.386.3734, AG6K,  

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