We're getting far off the topic of Elecraft radios ...
>
>
> Investigation showed that the steel chassis was not 100% flat and the
> contact surface of the rectifier was compromised.
Good lesson. Contact resistances need to be accounted for in the thermal
model and analysis.. They are never
If they are paralleling two 35A diodes in the new builds, they may have
repeated the same mistake.
Does this give a 50% derating (a typical factor) for full load forward
current?
I dunno. One can do the math [1] and figure it out.
A 50 A bridge (no need to parallel) is OK by design. That's
I've always put a bit of heat sink compound on the rectifier unit before
mounting it to the bottom plate. I've found several power supplies
where the bridge rectifier assembly failed and upon removal, there was
no heat sink compound. Add a new bridge assembly and some heat sink
compound
I can add perhaps another data point on the rectifier matter. Years back
my employer, one of the largest ground to air radio manufacturers was
having failures with their mainstay transmitter, a 50w carrier AM unit.
It had a large toroidal transformer and a packaged rectifier. The
rectifier
Another possibility is that is what they had on hand
Sent from my iPhone
> On Apr 24, 2020, at 3:13 PM, Ray Albers wrote:
>
> This thread started as my description of the failure of my Astron RS-20A
> power supply, caused by a bad electrolytic capacitor on the regulator
> circuit board.
Ray is correct. A study of the schematics for Astron linear supplies
makes it clear that nothing in the circuitry is referenced to the
chassis.The vast majority of PSUs are built so that V- can be bonded or
not. V- is NOT ground, it is V-. And in our systems, it should NOT be
bonded in the
No! That is the CORRECT thing to do; all grounds should equal ground.
You should reconnect that to the chassis ground, it is not a design flaw.
Rick NK7I
On 4/24/2020 12:11 PM, Ray Albers wrote:
Finally, I'll mention that, like my old RS-20A, I found the negative
terminal bonded to the
This thread started as my description of the failure of my Astron RS-20A
power supply, caused by a bad electrolytic capacitor on the regulator
circuit board. Several hams posted advice that a 20Amp supply was really
too small for a K3/100, especially if running full power. This led me to
order an
I had a ham mention to me that this power supply blew up. He was somewhat
annoyed when I ask if anyone was injured in the explosion.
Folks, for us trying to assist with technical issues, please give complete and
accurate descriptions. You will get better answers.
Bob, K4TAX
Sent from my
Or sometimes, just to get your attention, they will short out then
explosively go open with a bang. The is usually no doubt figuring out which
component is bad.
On Sun, Apr 19, 2020, 19:56 Christopher Hoover wrote:
> opens in my limited experience.
>
> On Sun, Apr 19, 2020 at 4:26 PM Adrian
opens in my limited experience.
On Sun, Apr 19, 2020 at 4:26 PM Adrian wrote:
> When you say 'blow' are you saying it short circuits internally or open
> circuits internally due to the event ?
>
>
> Adrian Fewster
>
> On 20/4/20 8:07 am, Christopher Hoover wrote:
> > You might want to
If the diode shorts, it Will cause excessive ripple from the half wave
rectification.
I suspect that the failure mode is an open causing the remaining diode
to carry the full current, which will cause its eventual failure.
In any case, paralleling two diodes without some form of resistance in
When you say 'blow' are you saying it short circuits internally or open
circuits internally due to the event ?
Adrian Fewster
On 20/4/20 8:07 am, Christopher Hoover wrote:
You might want to replace the bridge rectifier in that new 35A power supply.
Yep, right out of the box.
At some
You might want to replace the bridge rectifier in that new 35A power supply.
Yep, right out of the box.
At some point, Astron started shipping RS-35A's with a 25A bridge
rectifier. They paralleled two out of four of the 25A diodes twice over
to make, supposedly, a pair of 50A diodes for
Many to all who posted/responded to my recent post about an electrolytic
capacitor failure in my power supply. Lots of very interesting reading
about peoples' industry experiences - thank you!
Several have pointed out that using a 20A supply with my K3/100 is pushing
close to (or over!) the
15 matches
Mail list logo
