I admire your improvements but it seems that since most all toob sets
are collecibles, changing the circuitry in any way would cause them to
be no longer "stock from the factory", i.e. they'd be modified. And if
you did modify a collectible radio without telling the buyer, it would
be grounds for calling you a dishonest seller.

True to some extent, though it would be an easily reversed mod. The
real reason
manufacturers didn't install this circuit was that it would cost one
resistor and one
capacitor extra, plus the labor of wiring it in. In a consumer product,
every
fraction of a penny you can shave becomes significant after millions of
units
made. And most people didn't seem to mind the extra distortion.

And as you said, there's
probably not much point in it for most cheaper
radios.'''''''''''''''''''''''''''''''''''''''''' '''''



I have to agree with the sentiments here about collectables,
but one reason I don't bother collecting many AM radios is their
poor sound, and to improve them, you have to modify them,
and I do just that if there is no other way to repair them,
and if an owner is happy about it.
Hopefully they'll run well for another 50 years, and the next repairist
will have to make similar decisions I have.



This same technique should help the AM section of a tuner sound better,
in those
receivers where AM was an afterthought ("Oh, just throw in a 6BE6, make
that
6BA6 FM IF amp also do the AM IF, and use the diodes of that 6AV6 over
there...").