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several new packeteers using have a

Found at: 0x1bi.net:70/textfiles/file?hamradio/pk232dcddoc.ham


Recently, several new packeteers using PK-232s have appeared 
on  our local duplex repeater which is dedicated  to  packet 
frequency  should  be  very low since there  are  no  hidden 
terminals.  Almost immediately we noticed that the collision 
frequency had risen dramatically.   After some investigation 
nvolved in stepping on in-progress packets.  These stations

We were very puzzled as there have always been some stations 
on  the  repeater using PK-232s with no  apparent  problems.  
The new stations were asked how their station was configured 
and what method was used to get the DCD operation  adjusted.  
We were very surprised at the answers we got.   Every single 
one  of  the  offending stations had set  their  station  up 
exactly  according to the instructions in the PK-232 manual.  
However, contrary to the advice given in the manual, none of 
these stations had configured their setup so that they could 
connected  to the radio.   None of these new operators  knew 

We  obtained  a PK-232 and manual to try  and  discover  the 
exact  nature  of  the  problem.   What we  found  was  that 
although  the  manual is very complete  and  generally  very  
to be desired.  Specifically, in this case, the instructions 
operation  are  simply  incorrect.   If set  up  exactly  as 
transmission  by  another station on the channel!!   We  had 
found the cause of our problem.

the  manual for setting up a PK-232 and NBFM radio for  1200 
baud  packet  operation and use the method  presented  here.  
All your packet neighbors will appreciate it very much.

The manual is quite corect in all respects EXCEPT where they 
output   level  for  proper  demodulation  and  DCD  circuit 
operation.   The correct way to set these adjustments is  as 
follows:

     1.  At  least temporarily,  arrange to be able to  hear 
         the  receiver audio signal which is being  sent  to 
         the PK-232.

     2.  Set  the  squelch circuit on the radio  for  normal 
         squelched operation.  The DCD circuit in the PK-232 
         is  incapable of proper operation with  unsquelched 
         audio from the receiver.

     3.  While  monitoring  incoming  packets,   adjust  the 
         receiver  audio level so that the tuning  indicator 
         "spreads"  fully when receiving a packet  from  the 
         station  on  the channel which produces  the  LEAST 
         amount  of audio output level.   There are  several 
         limiters   in  the  PK-232  demodulator  so  louder 
         stations will not be affected adversely by this.

     4.  Once  the audio level is properly set,  adjust  the 
         DCD THRESHOLD control on the PK-232 so that the DCD 
         led lights when there is a packet being transmitted 
         by the station on channel which produces the  LEAST 
         amount  of  audio output from the  receiver.   Make 
         sure,  however,  that  the DCD LED is  extinguished 
         when  there  is no signal and the  radio's  squelch 
         circuit has cut off all audio from the receiver.

another  station  and  will  not  send  acknowledgements  to 
ndividual frames of a maxframe greater than 1 packet  while
t is still being transmitted.

We  hope PK-232 owners will find this information useful and 
take  steps to assure that their DCD is operating  properly.  
Multiple  access  packet  channel  throughput  is   severely 


Eric Gustafson  N7CL




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