On 4/24/2020 8:17 AM, Robert Sands wrote:
My Astron hums loudly only when the fax machine runs. Otherwise silent.
?interaction puzzling.
This strongly suggests one or more mis-wired outlets in your home.
Things like phase (hot) and neutral reversal, neutral and ground
reversal, or an additional bond between neutral and ground (there MUST
be one at the power entry panel, but there must NOT be one anywhere else).
I suggest that you start by checking every outlet with a good outlet
tester.
There's one other thing about Astron supplies that also might be the
cause -- the green wire is not properly connected to the chassis inside
the PSU, because the lug to which the green wire is soldered is
insulated from the chassis by paint. Check for this by measuring between
the green wire on the plug and the chassis with an Ohmmeter. You should
see a dead short. If you don't, open it up, scrape the paint under that
lug. While you're at it, remove the wire between V- and that lug. This
problem is documented in
http://k9yc.com/PowerSupplyBondingAndAudioDistortion.pdf
73, Jim K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
