[AMRadio] T3 Mod iron specs - Audio limitations, harmonics, etc.


Todd, KA1KAQ ka1kaq at gmail.com
Thu Feb 21 10:12:21 EST 2008


On Thu, Feb 21, 2008 at 1:47 AM, Ed Sieb <esieb at sympatico.ca> wrote:

>  "With the stock iron, there was a noticeable improvement in the low end
>  response. Further improvement can only be obtained by installing a different
>  modulation transformer.

Yep, not unlike the Valiant and a few others. They can be made to
sound 'better', but only to the limit of the iron.

My big xmtr was instead limited mainly by couple caps, resistors, and
so on. Done about halfway through the production run to limit response
and increase punch through the noise. Simple changes back to something
close to earlier values improved audio considerably, without dirtying
up the signal.

An OT once told me with respect to audio that anytime you add 'more'
stages, processing, etc, you also introduce more distortion. And
somewhere along the way I picked up the term 'outboard distortion' to
describe outboard processing. There are more than a few folks with
artificially-enhanced voice characteristics (added bass comes to mind)
resulting in audio that pops up and down the band 10+ kc/s either
side. Not sure it it's a result of where they added it inline or more
a product of bad set up. It would make sense that if you don't address
shortcomings in the rig like components or iron, and then run through
them to some degree, you'd be asking for trouble.

There are also some stations out there with custom audio that sound
fabulous, and have clean signals despite being a bit wide in the eyes
of some. So it can obviously be done right. No doubt has a lot to do
with what you're trying to push the outboard audio through. The old
saying 'you can't polish a turd' comes to mind...

~ Todd,  KA1KAQ


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