Re: [BPQ32] Multidrop KISS problem SOLVED:-)
- This is probably because mose new serial hardware uses a charge pump power
supply design to create a negative power source (high source impedence) for
the port. A -12 volt source may be too much for the serial port to switch to
the posative side hence use to serial port for the negative power source.
Possibly changing the value to 100k or higher may also fix this issue.
James C. Moore PE WU3V
Staff Engineer 4
----- Original Message -----
From: "chris_g0cng" <chris_g0cng@...>
Sent: Sunday, September 18, 2011 07:23
Subject: [BPQ32] Multidrop KISS problem SOLVED:-)
> You may remember me posting to the group about a month ago an issue I was
> having with my Multidrop KISS system stopping polling the 4 TNC's on my
> system and therefore the radio ports going dead at random intervals.
> Thanks to Peter G6KUI, Sysop of GB7DBY in Derby, UK. He also looks after
> the Derby Club DXCluster system which also uses BPQ32 in Multidrop KISS
> He was experiencing exacly the same issue, and he solved it by removing
> the 10K pulldown resistor to -12V from the PC Com Port RXD pin on the Com
> Board and instead soldering it directly across one of the diodes in the
> TNC D Connectors, performing basically the same job. He commented that
> since he did that he had no further problems.
> I did the Mod about a week after I sent the original post mid August and
> am delighted to report that I've had no further problems.
> It really does work.
> The original problem was clearly down to RS232 voltage levels on the PC
> RXD line.
> Hope thi may help anyone else having similar problems.
> Chris G0CNG
> Sysop GB7MAX and BLOX running MailChat BPQ-220.127.116.11 and BPQ32 Node.
> Yahoo! Groups Links