[R-390] in rush current limiters

[Walter Wilson]

Todd,

Inrush current limiters do indeed get and stay hot when in use.  Also, they
must be properly sized for the equipment.  That's one of the problems with
the ePay version:  depending on the current limiter selected, it is
optimally sized for a certain load.  These things also have max current
ratings.

For instance, the CL-80 (commonly used in the R-390A), is rated at 47 ohms
when cold, max current of 3 amps, and resistance drops to about 0.5 ohms at
max current.  If you were really pulling the max 3 amps through the limiter,
you would expect a voltage drop of about 6 volts (current/resistance).  Used
in the R-390A with the ovens OFF, the drop across a CL-80 current limiter is
between 2.5 and 3 volts.  So if incoming line power is 120 VAC, the radio
will only see 117 VAC after the 3 volt drop across the limiter.  This is not
a bad thing, since the receiver was designed to run of 115 VAC.

But it is apparent from these observations that a "one size fits all"
solution is not really valid here.  If you have one of these ePay solutions,
just don't go plugging your power bar into it to feed the whole station.

Walter Wilson - KK4DF
http://r-390a.us
(REAL Radios: R-390A, R-390, T-368E, Ranger, Thunderbolt, KWM-2A)

----- Original Message -----
From: <ToddRoberts2001@aol.com>
To: <r-390@mailman.qth.net>
Sent: Thursday, January 02, 2003 12:54 AM
Subject: Re: [R-390] in rush current limiters


> <PRE>Let's see - the item on eBay - take a dual outlet (69cents) a plastic
outlet
> box (69cents) a small 3-wire line cord (99cents) two current inrush
limiters
> $2, a small circuit breaker (99cents) - put the thing together for $5-$6
> bucks and sell it for $30 bucks on eBay. Sounds like a nice profit margin!
> One thing I am not fully sure about current inrush limiters is - don't
they
> run "hot" in normal use? And do they fully return to zero resistance when
> they are at operating temperature? - Todd Roberts WD4NGG.
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