World of Ham Radio 1997/WOHR97_AmSoft_(1997-02-01).iso/mods/aea/232pwr.doc

Internet Message Format | 1997-02-01 | 2KB

From: WB2ZTK@WB2ZTK
To: ALL@ALLBBS

Hello Out there....

I've just completed my work on the PK 232.  I mention earlier in the week
of a problem with the PK 232 regarding RFI and how the 13 volt supply line is
unprotected from accidentally placing voltages above 13.6 into that box.
This 13.6 v line is connected to a couple of IC and branch to many transistors
and is use as a pull up voltage for many circuits within the box.

Well now that the highly stable voltage regulator in in place along with
a RF choke of 20 uH.  I can easly hear some of our checkins during
the my Faxnet on 28.450.  The RFI from that box was of the low level type and
was knocking out the weak station when the unit was on.

I am very happy with the addition for two reasons.

1.  It protect the PK 232 from Murphy and I.
2.  It gives my rig isolation from the RF that was leaking down the power
    supply leads to a common power supply shared with the rigs and other
    devices.

For those that plan to add this protection, you'll find plenty of room inside
the PK 232 to place this additonal Voltage reg.  You might want to consider
adding a bridge rectifier and 120 to 18 v @ 1 amp transformer, and connect
the voltage regulator to that.  I feel that the voltage regulator should
be internally placed in the PK 232 along with the choke because of the
leakage that was coming from the leads to a external supply.  Some will
find that placing ferride beads to help from this leakage, and keeping their
external supply as is.  Well some of us use power supplies that are ajustable
and might apply voltages above 18v to the PK 232.  The internal voltage
regulator protects against this over voltage and choke blocks the RFI,
this placement makes the best sense to me and thats how I went.

Having fun and feeling safe, Dan...   WB2ZTK...