PK-232 mods op amps

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
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.

    Are  you  having  trouble with your PK-232  Locking  up  (not returning to receive mode) when a high RF signal is present?   If so AEA says to add a .01 MFD Capacitor across D30.

    D30  is  located  in lower right hand corner of  Main  Board, parts pictorial page I-1 of operating manual, just to the left of JP2 and JP3 beside SW-2.

I hope this helps, it stopped my problems ……

GW1NGL NA7KR Kevin Roberts Ham Radio

Page last updated on 09/10/2012 by Kevin Roberts NA7KR a colection of Ham Radio and Electronic Information