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
worst case
steady-state anode current, the maximum resistance that could be used with the
5 watt
resistor would be ~9 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, or
are there
other factors that dominate the discharge time (capacitor ESR, stray
inductance, etc).
Thanks,
Mike, W4EF............
----- 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 prone to flash over
> >> > due to the relatively small gap between the leads and the metal 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
>
--
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