Tnx for the support, The chip should be cold; i found the problem. One of the outputs (pin 5) gave the problem; i measured a resistance of 250E. After replacing the chip the problem was over; the chip stayed cold.
73 Johan PA3GSB --- In [email protected], "johanmaas2001" <[EMAIL PROTECTED]> wrote: > > Hi Alberto, > > The strange thing is that the system is working.... (your program is > also running fine) > > i tried several things without getting the temperature down.. > > - i have removed the bias circuit > - is disable the chip by suppling +5V to the pin 1 en 15 (ENA and ENB) > > I found a difference in the QEX schemes : > > page 23 Mar/April and page 7 july/aug; > > The connections at the output side are different: > > 3-10; 4-11; 5-12; 6-13 (iam using this scheme) > versus > 3-13;4-12;5-11;6-10 > > Can that be a problem? Which connection is right? > > > 73 johan PA3GSB > > --- In [email protected], Alberto I2PHD <[EMAIL PROTECTED]> wrote: > > > > johanmaas2001 wrote: > > > > > > The QSD uses a fst3253; the temperature of the chip is high (i can > not > > > measure the temp because i do not have a probe); i can not hold my > > > finger on it.... is this normal behaviour? or is there something > wrong? > > > > > There should be almost no power dissipation in the analog switches, > > whatever model or brand they are. If yours get so hot that you can't > > touch them, something is definitely not functioning as it should... > > > > 73 Alberto I2PHD > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
