>
>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, www.vcnet.com/measures.
end
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