Hi Eric
It isn't a continuous hum, nor does it sound like a small transformer. It
comes on for perhaps 15 seconds, sometimes more, then goes away. Nothing
shows on the front panel when this happens as it is off but back panel
switch is on. It sounds more like a big transformer hum.
I've got a
I leave my KPA500 back panel switch in the ON position most of the time and
use the front panel switch to bring it to life.
However in even when in the Front panel off/Back panel on state the
KPA500 will occasionally hum for a few seconds.
Is this normal? Any suggested causes to worry about?
Jim
The KPA500 turns on the fan momentarily when you use the front panel on/off
switch. I believe this is to bleed off voltage in the internal power supply. It
is a design consideration not a problem
Harlan
NC3C
Sent from my Verizon Wireless 4G LTE DROID
Jim Miller j...@jtmiller.com wrote:
Jim,
My first KPA500 did that occasionally, so I don't think it's an issue.
I'd guess it has to do with line voltage variances.
73,
Scott, N9AA
On 6/11/13 10:51 AM, Jim Miller wrote:
I leave my KPA500 back panel switch in the ON position most of the time and
use the front panel switch to
Jim;
Make sure the transformer is bolted down appropriately. If it works loose then
it will cause the hum.
Jack Brindle, W6FB
On Jun 11, 2013, at 7:51 AM, Jim Miller j...@jtmiller.com wrote:
I leave my KPA500 back panel switch in the ON position most of the time and
use the front panel
It's not fan noise. It's definitely 60hz hum likely due to transformer for
some reason. This was a factory assembled unit. I'll take the lid off and
check it out the bolting. I'm currently running on a shared household
circuit with who-knows-what connected elsewhere. The shack will get a
dedicated
I have a kit-built KPA500 that has the same issue.
It's well grounded and all the bolts are tight.
The humm is barely noticeable when off but definitely there.
73
Stan AE7UT
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My kit built hums but only periodically - more like a cycle and certainly not a
continuous hum. When it happens I can fear it if the room is quiet. Capacitor
recharging?
On Jun 11, 2013, at 12:13 PM, Stan AE7UT ae7...@gmail.com wrote:
I have a kit-built KPA500 that has the same issue.
It's
Jim,
As someone else mentioned, it is most likely due to line voltage variance.
Even though they are on different circuits, whenever my wife uses the blow
dryer, the KPA500 starts humming along. I guess that doesn't speak well
for connections somewhere between the electric company and my ac
This is normal and is due to the small low voltage transformer and
rectifiers that provide power to the front panel microprocessor. turning
off the rear switch will turn everything off, including this transformer.
Eric
elecraft.com
On 6/11/2013 10:13 AM, Stan AE7UT wrote:
I have a kit-built
I had this happen and discovered that the laser printer I had was plugged into
the same ac circuit and was causing voltage drop periodically. Moving the
printer to another wall outlet fixed the problem.
Matt NQ6N
On Jun 11, 2013, at 5:03 PM, Eric Swartz - WA6HHQ, Elecraft
e...@elecraft.com
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