Relay-Version: B 2.11 6/12/87; site scolex Path: uunet!uunet!iWarp.intel.com!inews!cad412!dbraun From: dbraun@cad412.intel.com (Doug Braun ~) Newsgroups: rec.aviation Subject: Re: Portable Lorans - PL99 Serial output question Keywords: loran,pl-99 Message-ID: <5055@inews.intel.com> Date: Tue, 09 Jul 91 16:03:22 PDT References: <1991Jun29.074606.4774@craycos.com> <9244@ucdavis.ucdavis.edu> <1991Jul03.063130.10973@pmafire.inel.gov> <1991Jul5.031049.604@kroywest.kroy.com> Sender: news@inews.intel.com Reply-To: dbraun@cad412.UUCP (Doug Braun ~) Distribution: usa Organization: Microprocessor Component Group, Intel Corp., Santa Clara, CA Lines: 71 In article <1991Jul5.031049.604@kroywest.kroy.com> arkin@kroy.com (Mike Arkin) writes: >I too picked one of these up, got the mating connector for the >power/serial output connector ($2.10 at local electronics place), >wired it up, but so far have been unable to get anything out the >serial port. Could one of the rec.aviators who bought the "accessory >kit" buzz out the included power/serial cable and see if it matches >the description on page 57 of the Owners manual? > >I did of course enter the FN19 to enable the port. I did not supply >external power (figuring it would probably work without power on that >cable). > The diagram in the manual is misleading about the data port. The data pin is actually an open-collector output, and the fourth pin (described as unconnected) is apparently about a 10K ohm pullup to +12V. So you need to connect these two pins together to get an actual voltage swing. Once I did this, connecting it directly to the data in pin on the RS-232 connector on the back of a terminal displayed the data on the screen. I think you are supposed to drive an opto-isolator with these two pins. Also, I am describing this from memory, so don't blame me if you smoke your PL-99 while trying this. Someone mentioned that they could connect an antenna directly to the BNC socket. Really? I would assume that the low impedance (thousands of ohms) of the BNC socket due to the power supply would kill the signal. I made a simple active preamp that ran off the 12 volts on the BNC connector: BNC >----------- | | | .01 uf | || _| D ANT>--||________|| || | G || Any FET suitable for RF amplification \ -| S / |------------------- 2.2 \ \ | MEG / / ----- \ \ 300 ohms _____ .1 uf | / | | \ | | | | | | | GND GND GND This is basically a broadband, low voltage gain, impedance matching amp. It gave really strong readings, but in one place I noticed that the unit gave a 10us error for one TD compared to the whip antenna. Possibly some interference was distorting the signal. A tuned circuit might help, but that's more complex to build. I built this into the base on a cheap magnetic-mount CB antenna. Doug Braun Intel Design Technology 408 765-4279 dbraun@scdt.intel.com or maybe: / decwrl \ | hplabs | -| oliveb |- !intelca!mipos3!cadev6!dbraun | amd | \ qantel /