CCWN 75:28
                                                        
        All outputs should have the following network applied at
the phono connector within the shielding of the standard. This
will insure a good TTL logic level and the 75 ohm resistor will
absorb line reflections. The +5 volt supply is also used to power
other units. An increase  of the filtering to 6,000 Mfd, an RF
choke directly in the +5 volt lead, several .1 Mfd and .001 Mfd
bypass capacitors were necessary to keep the Vcc lead clean of
undesired signals, in particular the 50 Khz signal and its
harmonics, including 3550 Khz, which will interfere with the
TEN-TEC receiver.       (2) The Keyer                             
 To provide the precise frequency timing characteristics required
for a CCW Morse generator system, the keyer circuit must be of
the type that begins and ends the dit and dah elements in precise
step with the clocking signal, as opposed to the more common type
of keyer that activates separate clocks for dit and dah
operation. This precision operation must be divorced from the
timing inaccuracies that may be injected by the operator as the
keyer paddle is operated.             WB2DFA has designed an
excellent CMOS keyer (HR, 1974) which can be easily modified to
accept the TTL output of the frequency standard and inexpensively
constructed. The keyer was built on perfboard, and is shown in
photo 4. Modification of WB2DFA's circuit is shown in schematic
2, which shows how the frequency standard synchronization or
timing signal is used to act as the clocking signal for the keyer
when CCW operation is desired. Switch Sa permits a return to the
internal clock present in the unit when variable speed non-
coherent operation is desired. The keyer is powered by a single 9
volt battery, which has a very long life due to the low current
drain characteristics of the CMOS devices.       (3) Frequency
Stabilizer and TEN-TEC Modifications               The TEN-TEC
PM-1 was selected for conversion because of its low cost and
extremely simple design that is duplicated in several other
home-built and commercial kit designs. The main advantage in CWs
conversion is that there is only one free running oscillator in
the unit that must be stabilized, where a more complex
transmitter or receiver system would require much greater expense
and complexity to adequately stabilize to the tolerance required
for CCW work.