MICOR 220 mods

EXCITER MODIFICATION

Modification of the exciter consists of changing 16 capacitors to move up the
resonant frequency of each tuned circuit.  The multiplication factor of each
stage remains the same.

Make the following changes:

c-430   75pf    c-447   10pf
c-433  150pf    c-448   15pf
c-434  110pf    c-451  4.7pf
c-437   20pf    c-452  7.5pf
c-439   21pf    c-455  3.8pf
c-440   51pf    c-460   75pf
c-443   15pf    c-456    5pf
c-444   12pf    c-458  1.5pf

The crystal formula remains the same:

                                           Fc
                                    Fo = ------
                                           12

Crystal specs are the same as the standard Micor.

Align the exciter according to the Micor manual.  You should get about 400mw
into a dummy load.  Do not operate the exciter directly into an antenna, as it
has no output tuning.  The exciter will drive a 15 watt VHF Engineering
amplifier to full output.  This mod was made to a TLD5132A Micor.
Other Micor exciter mods should be similar.


RECEIVER MODIFICATION

Modification of the receiver consists of modifying the RF preselector and changing the oscillator multiplier stage.  The original multiplier stages uses third harmonic of the crystal; after mods it will use the fourth.

Make the following changes to the receiver board.

c-108   27pf    c-113   2pf
c-109   39pf    c-116   2pf

Use the same type of caps as the original.  If you have the 142-150.8 or the
162-174 MHz version of the Micor receiver, you will not have to chnge c-108
and c-109

Crystal formula for the modified receiver is:
                                                Fc - 11.7
                                         Fo =  ----------
                                                   12

The crystal frequency will be in the same general range as before because it
is multiplied 12 times instead of 9.  The crystal specs are the same as for the
original Micor receiver.   Align the receiver according the to Micor manual.
The modified receiver should meet the original Micor specs.