[Premium-Rx] Racal RA6778C - Product Safety Advisory (Oh MY!!!)

[mcolby at mcolby.com]

Steve,

In my professional experience (computers), TrippLite makes some good
power strips/surge protectors. (Look at the good/high end ones, as
almost everyone seems to have a cheap 'China import' line these
days.....)

Martin

> -------- Original Message --------
> Subject: Re: [Premium-Rx] Racal RA6778C - Product Safety Advisory (Oh
> MY!!!)
> From: Steve Stutman <steve at oceanrobots.net>
> Date: Sun, August 28, 2005 5:48 pm
> To: Ben Dover <quixote2 at ix.netcom.com>
> Cc: premium-rx at ml.skirrow.org
> 
> Hi All,
> 
> Follow on question:
> 
> Any suggestions as to an AC "power strip" which has a switch/outlet?
> 
> Mains power switches made of unobtainium are not unique to 6778.
> 
> 73,
> Steve
> 
> 
> Ben Dover wrote:
> 
> > Greetings, Group.
> > 
> > I had a rather odd incident occur this week that I think I
> > should pass along to other owners of this rig. It COULD 
> > possibly be an operator safety or fire hazard issue.
> > 
> > I was taking the rig out of it's usual shack location to haul
> > it on a trip to visit another Premium Receiver fan. While it
> > was sitting on the floor, I decided I wanted to check what I
> > had programmed into the memories, and plugged it back in.
> > 
> > When I flipped the AC power switch, the shack's receiver
> > isolation transformer gave an alarming grunt from overloading,
> > and I saw the Premium Receiver Nut's Worst Nightmare; a BIG
> > puff of smoke rolled out of the back of the radio, and the 
> > isolation transformer's breaker tripped.
> > 
> > Quick investigation showed the radio's fuse to be OK, and the
> > proper rating. An ohmmeter across the plug showed open in both
> > AC switch positions.
> > 
> > Pop the dust covers and dig in deeper... The AC power switch is
> > DPDT, and it showed a DEAD SHORT across the AC line in both
> > positions!
> > 
> > Grabbed a screwdriver to pull the rear panel & allow removal of 
> > the power supply module, and there was the source of the smoke;
> > on each lead of the incoming AC line there are ferrite RF chokes
> > and bypass capacitors. The plastic heat shrink tubing of one of
> > the chokes was melted. Removing the choke & doing an ohmmeter
> > check showed it was open; the choke had done a splendid job of
> > sacrificing itself to protect the fuse!  ;o)
> > 
> > Quick, temporary repair was a simple matter; strip off the burned
> > winding, clean the ferrite core, and put on a new winding... but
> > the AC switch, the source of the problem, is a different matter.
> > 
> > 
> > I've long been of the opinion that the RA6778C is a receiver that
> > is designed to be turned on and LEFT on 24/7 for weeks or months 
> > at a time. The AC switch is an oddball unit, made to fit the small 
> > space available on the front panel. It is QUITE flimsy; essentially 
> > a Rat Shack type mini toggle switch fitted with a large switch's 
> > mounting bushing and bat handle.
> > 
> > As hams and SWLs we use the radio differently than the original
> > owners; we turn them on and off a LOT, while the original users 
> > might power them down once every 6 months or so. The switch is
> > good enough for occasional useage, but daily? NO WAY!
> > 
> > Dissecting the switch it looks like the internal sliding contact 
> > somehow rotated 90 degrees and wound up shorting out the AC line.
> > 
> > For the moment, the switch leads have been soldered together and
> > covered with heat shrink tubing, and the rig is running fine.
> > However, finding a more robust switch that will fit into the space
> > provided is going to be a challenge. In the meantime until a
> > solution to the problem shows up the receiver AC power is being
> > controlled by the switch on an AC outlet strip.
> > 
> > Just thought I should pass this one along.
> > 
> > 
> > 73's,
> > 
> > Tom, W9LBB
> > 
> > 
> > 
> > 
> > _______________________________________________
> > 
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> 
> 
> 
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