How about during normal operation? What power supply?
Thanks
73
Jim W7RY
On 6/2/2020 7:48 PM, Artek Manuals wrote:
During the Bench testing I have an Astron R-35 more than up to the
brick's challenge of 10-15 amps and fairly short power cable less
than 18"
Dave
NR1DX
On 6/2/2020 8:38 PM, Jim wrote:
What are you using for a power supply to run this amplifier?
Thanks
73
Jim W7RY
On 6/2/2020 7:33 PM, Artek Manuals wrote:
This is going to seen trivial to many of you but some times the most
puzzling problem has the most simple solution, worth sharing.
The " 60W-brick" ( an old Mirage C106) on the 220 "lets chase
DX"-repeater had given up the ghost. No power on light ...hmmm
checked and the fuse on the back panel fuse holder� looks absolutely
perfect. So out of the rack and back to the home shop for a more
detailed autopsy. After 5 minutes of poking around with the VOM it
seems the fuse is actually a zombie fuse, meaning it looks OK but in
reality it is open with no sign life or the cause of death, usually
15 Amp fuses die pretty spectactularly. Oh well pop in a new fuse
and it is off to the races. But the amp is only putting out 40-45 W
and it is supposed to be 60W? Playing for 10 more minutes and
nothing seems out of the ordinary..oh well it is 30 years old anyway
button it up and move on to the next project right? As I put the
cover back on I happen to absent mindedly tighten the fuse holder
cap and it is VERY WARM ...now wait a minute fuse holders aren't
supposed to be that warm? Further measurement shows� a little better
than .5 volt drop across the fuse holder under load. A little
loosen-tighten cycles and it is down to .25 volts . Upon closer
inspection the spring inside the fuse holder looks dark and crusty (
like the one in your flash light after the batteries leak). So I
have some really nice fuse holders in the junk box with bright shiny
copper insides , replace the fuse holder , no more voltage drop and
the brick is at 70W out.
The moral is the old fuse holder was corroded internally to the
point that it's contact resistance had gone up enough under load to
heat the fuse contact end and melt the solder inside the fuse. The
bigger take away is that if something seems a bit odd keep looking.
This one was easy but in 50 years of tinkering I had never seen a
bad fuse holder and now I wonder how many I over looked over the
years 8^)
Dave
NR1DX
manuals@artekmanuals.com
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