[TenTec] Ear Phone Audio

[Jim Brown]

On Thu,8/25/2016 2:16 AM, Barry N1EU wrote:
> Point of information:  when I owned an Orion 565, I also used Sennheiser
> HD280 headphones.  I needed to crank AF Gain to maximum to get decent
> volume.  I spoke with the factory and they told me there were series
> limiting resistors at the headphone jack and I might want to lower the
> resistance of said resistors.  I believe I cut the value of those resistors
> in half and was very happy with the extra volume.
Those are the resistors I spoke of that protect the output stage from 
being shorted when phones are inserted in the jack. It sounds like the 
design might be overly conservative.

> My guess is this is what might be happening here - nothing is actually
> broken, but maybe I'm wrong.

An important question is the one that I learned to ask when being 
trained to do field service on complicated systems. "If the damn thing 
was working yesterday and it ain't working today, there can't be that 
much wrong with it, so what changed?"  If the loss of loudness occurred 
when a different set of headphones was used, I'd suspect the resistors. 
If it's same headphones, it ain't the resistors. :)

73, Jim K9YC