One little fact you might want to consider regarding hum and
iron core transformers: The cores are designed to restrict
the coupling to include only the windings on the core (that
part is obvious), but if you bring two iron core transformers
into close proximity, the magnetic field in one core "likes" the
iron in the close-by core as well, so the signals in one
transformer are cross coupled to the other.
The result is that using an isolation transformer can actually
introduce the exact problem you were trying to avoid by installing
it. The fix, of course, is to get the cores farther apart. I had
a similar problem when the little Radio Shack isolation transformer
between my PC and my rig Mic jack found itself snuggled up to the
side of the blower motor behind my homebrew amplifier.
Wayne
> -----Original Message-----
> From: writelog-bounces@contesting.com
> [mailto:writelog-bounces@contesting.com]On Behalf Of Garry Shapiro
> Sent: Saturday, February 01, 2003 23:23
> To: WriteLog Reflector
> Subject: [WriteLog] Hum progblems...
>
>
> Since my previous posting, asking about PTT, I did an
> on-the-air sound check
> and learned that, with my amplifier on---even in standby--I
> have excessive
> hum on my signal. The reports indicate less hum with the
> amplifier off, but
> I can hear it in the monitor with the amp in standby. So I
> will have to run
> Sprint without any sound buffers.
>
> I have the Rigblaster mounted on the left side of the MP and
> the amplifier
> is immediately adjacent. Disconnecting the mic from the
> soundcard changes
> nothing and disconnecting the Rigblaster kills the hum---I
> must be getting
> pickup from the amplifier's power transformer directly into
> the Rigblaster.
>
> Not a Writelog problem---so I will take my problem off the reflector.
>
> Garry, NI6T
>
>
>
>
> __________________________________
> 160 meters---not a band but an obsession
>
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