[ARC5] ARC-2

[David Stinson]

Addressing the AN/ARC-2 on CW:
Though I can't prove it, I think it unlikely that CW
with the ARC-2 was used any more often than it
would have been with any other WWII Command set.

For one thing- stock condition, it's a lousy CW set,
and I don't mean the broad receiver.  The BFO injection
is weak, bordering on pathetic.  Almost unusable.
I've had three pass through here and all had the
same issue.  Fortunately, there's a easy fix- increasing
the value of one easy-to-reach capacitor.

Now, it's been many years since I did this and my
memory may be as faulty as the rest of my carcass,
but I just looked at the schematic and I *think*
(hope) this is right:

C202 is a 10pFd cap which couples energy
from the Master Oscillator into the signal grid of
the 1st IF, connected by the "CW Relay."
I remember it being easy to reach on the side of
the rig near the front.  Increase it to 50 pFd.
  It makes the level acceptable and usable.
Not great, but it works.

Be very careful with a soldering iron in an ARC-2.
Learned the hard way while
experimenting, looking for a non-destructive way
to tighten the IF selectivity (no joy).
There isn't much room to work and
the insulation melting temperature of the wires
and little shielded cables is very low;
  they melt like butter.  Be careful with the heat
or you'll be pulling modules to replace the melted
and shorted wires, and probably melting and
shorting the wires you disconnected to fix
the first ones you melted.  It's a "hair puller."

Also note:
Metal tubes in the ARC-2 must be replaced with
metal tubes.  The shielding is part of the design.
If you put glass tubes in the IF, you'll get feedback.

GL OM DE Dave AB5S



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