[ARC5] BC-453 Mods

[Leslie Smith]

Neil & Others,
Can I suggest you get the best of both worlds? - modification but close
to original.   There are a number of circuits that can be found on the
web that give solid-state functional replacement for "toobs".  These are
built into sockets (octal sockets) that plug in - as a direct
replacement for the valves you will remove.  In this way you can
"modify" the set without changing it.  When you want to restore the set
to original, it's possible.  You must make some mods - in particular to
the plate dropping resistor in the local and beat frequency oscillators.
 These resistors have high values; they will drop most of the B+ supply
across them.

In the case of your set, there will be enough room on the card (built
into the octal base) for your BFO.  

On the other hand, at 60 volts B+ these sets operate quite nicely, and
run cool;  I get great enjoyment from running the set unmodified, or
with minimal mods.

A typical power supply giving 60V B+ from a 24V filament supply can be
found in "files" on the yahoo group "ARC-5radio".    As a general rule I
try to keep original sets original, and get the "modded" sets running in
using good quality wiring practice.

Good success!

  Leslie Smith
  vk2bcu at operamail.com


On Sat, 06 Aug 2011 15:29 +1200, neilb at ihug.co.nz wrote:
> > I vote for the recommendation to use a solid state BFO and
> > get a transistor that will operate from somewhat higher Vcc
> 
> Back in the 80's I replaced RF & IF stage tubes
> with FETS with great success.  Used MPF102's
> soldered to the tube socket tags.  Suggest you
> go that route since FETS are closer to tubes
> impedance-wise.
> 
> 73 de Neil ZL1ANM
> 
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