pk232.27

Recently, several new packeteers using PK-232s have appeared 
on  our local duplex repeater which is dedicated  to  packet 
radio.    This   is  one  environment  where  the  collision 
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 
we discovered certain stations were almost guaranteed to  be 
involved in stepping on in-progress packets.  These stations 
were  contacted and in all but 1 case they were new users of 
PK-232s.

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 
hear  what was going on on the channel when the  PK-232  was 
connected  to the radio.   None of these new operators  knew 
what DCD meant, what it did, or why it was important that it 
should be working on a multiple access packet channel.

We  obtained  a PK-232 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  
well written, there are some areas where it leaves something 
to be desired.  Specifically, in this case, the instructions 
given  on page 2-16 (we had manual PK232UG Rev.  B 9/86  for 
reference) for setting up the PK-232 and an FM radio for DCD 
operation  are  simply  incorrect.   If set  up  exactly  as 
described,  DCD  will  NEVER  be asserted  during  a  packet 
transmission  by  another station on the channel!!   We  had 
found the cause of our problem.

If  you  have a PK-232 and haven't already  discovered  this 
problem for yourself,  please disregard the instructions  in 
the  manual for settineration and use the method  presented  here.  
All your packet neighbors will appreciate it very much.
continued in pk232.28