[Hallicrafters] SX25 mods

[Mark Bell]

Good Morning Peter --

I'm ordering parts to recap my SX-25.   If you'll look at the schematic, all
the "old" value parts (such as the 0.05 uF cap) are all in bypass
applications.  So, the usage of "new" value parts (0.047uF) isn't going to
matter at all.  The tolerance of the original parts was so bad, any new part
of close value will probably not be noticable.

As for keeping the radio original,  if you're not going to stuff the new cap
inside the old one to preserve the original look, don't worry about the
value!!

A radio that has been modified with modern components, but can be "reversed"
to original components should you want to sell it,  shouldn't be a problem.

Using a solid state replacement for the rectifier isn't a problem; just be
sure to socket the diodes and put in a dropping resistor.  This may not look
original,  but a blown power transformer that needs rewound isn't something
you want either.  Besides, you can always pop out the diodes and replace it
with the tube for "show and tell" evening!!   Similarily, rewiring for the
5Y3 isn't a problem because it can be undone in the future.

> During WW2, there was a shortage of all US numbered valves (tubes) used in
> allied radio equipment, the services did not use the side contact valves
(O
> series and A series) so this Airzone set was completely rewired using the
> Philips valves because of practicality and availability, it's a real
curio!

Sounds like a unique piece of history you have there.  You might consider
leaving  it like that for historical purposes.  It may not be factory
original, but it is "original" as it was really used that way during WW2 !!

Just my rambling comments OM !!

73 Mark K3MSB