[ARC5] BC-455 adventure

[Mike Hanz]

John F reminded me that there are things you can do (when you design a 
set like the 3801) to mitigate the stability problem, like maintaining 
the field at a full 24v whenever the dyno is running and only switching 
in a series resistance to lower the *armature* primary winding voltage.  
That's a bit tough to do with a command set dyno - you would have to 
modify it to bring out the armature and field separately, and then you 
still need either two supplies or a high wattage resistor.  The little 
buggers just don't have enough room in 'em! :-(

On 6/16/2012 4:48 PM, Jack Antonio wrote:

> And then there is the little Bendiz 3801 set.  This is
> something like an RCA AVT-112/AVR-20/AVR-15/AVA-126 all
> rolled up into a two unit set.
>
> Pertinent to this topic. The set has one dynamotor, which
> is around 500V output.  In receive, it is fed voltage through
> a resistor which reduces both speed and output voltage. In transmit,
> the resistor is shorted, allowing full speed and output voltage.
>
> The resistor is mounted in one of the end bells of the dynamotor, and
> is cooled by a fan on the motor shaft.
>
> It works, but the transition from transmit to receive, sounds a bit
> harsh in the headphones.