TTL level transmit data is present on the FSKN and FSKR
pins on J7 of the PK-232 regardless of the position of
the RADIO 1/RADIO 2 switch.  When left connected to the
direct FSK keying inputs of many HF transcievers, the
data on these lines will cause noise on the HF transmitted
signal on other modes (SSB, FM, etc.) when the other port
is being used on another radio. Further, to use direct
FSK keying, one must split the interconnect cable at the
PK-232 end because the receive audio and transmit FSKN/R
signals use different connectors on the PK-232.


Select either the FSKN or FSKR signal (whichever you use)
and substitute it for the SQUELCH input on J4 and J6. This
allows the TTL level transmit data to appear on J4 and J6
pin 3 as selected by the RADIO 1/RADIO 2 switch. This
eliminates both of the above problems. This modification
requires no trace cuts or drills and may be easily restored.


  1. Select the appropriate signal for your application.
  2. Remove R150
  3. Ground the base of Q6 using a jumper to the pad left
   by the Q6 side of R150.
4) Connect a jumper between the pad on the SW2 side of
   R150 and U38 pin 2 or pin 8 depending on your choice
   in step 1.

NOTE: The pinouts on J7 for FSKN and FSKR are reversed at
      U38 on some PK-232 schematics. FSKN thus appears on
      U38 pin 8 and FSKR appears on U38 pin 2. The labels
      on J7 are correct.

GOOD LUCK and 73, Rod NR7E @ W6PW-3

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