[ARC5] T-22 and BC-459 coil compatibility?

[Mike Morrow]

Ian asked:

>Can the TX coil assembly (1625 plate/ant link) from the BC-459 be used in
>the T-22?

Well...they are not the same.  This is T54.  The part number for T54 in the
BC-459-A is 7250, and T54A in the T-22/ARC-5 is 9295.

The AN/ARC-5 version relocates the terminal for the top of the PA coil about
60 degrees CW (looking down on the coil) and about a half inch below the top
of the ceremic.  This is to allow the installation of the HV blocking capacitor
C72 between top of the coil and the terminal at which HV is connected in the
AN/ARC-5 version, due to the HV shunt feed of that model.  The BC-459-A version
is series fed, so the HV connects at the bottom of the coil and no blocking
capacitor C72 is required.

I suppose you could kludge in the 7250 in a T-22, but it will be clumsy and
require somehow separating the top of the 7250 coil from the terminal it's
attached to, and installing a DC blocking capacitor (C72 = 0.0004 uF) between
the coil top and the HV supplied at the top terminal.

FWIW, the coil turns are laid out differently on the two assemblies.  The 7250
has six turns, while the 9295 has only six.

>72, ian K3IMW

72?  QRP?  :-)

Mike / KK5F