I can add some insights to way-ward receivers that are missing the down converters. You can indeed fabricate replacements or like I have done for several units like Austrons adapted Odetics downcoverters in. This is not at all easy you have to be time-nutty to do this. It takes reverse engineering and than almost always a mixer and local oscillator to shift the signals around. Some of the old rockwell and other gps receivers had nice IF frequencies at 35 Mhz. Easy to work with. However the more integrated a receiver is the less likely you can access what you want like IFs and LOs. One key thing I ran into is that the receiver you want to make work has to control the first LO. So that means as an example in the Austrons case using its 10 MHz LO to multiply up and that same signal had to replace the rockwell 10 MHz crystal.This required a TTL to PECL conversion and some really small wires. You could actually go a more direct route these days and build a LO chain to 1.5 GHz using PLLs they seem pretty reasonable. Most of the converter schemes I have reversed engineered seemed to produce a 74 MHz IF or 35 Mhz. Good luck and if the receiver is going to be scrapped I might want to tinker. Good luck if you move forward. Regards Paul WB8TSL
On Thu, Apr 30, 2015 at 1:55 PM, Alex Pummer <[email protected]> wrote: > I am not so sure that it is applying to that case, but there are GPS > antenna cable extenders which converting down the incoming GPS signal to > frequencies at which the cable attenuation see here: > http://www.microsemi.com/products/timing-synchronization-systems/accessories/government/l1-gps-antenna-down-up-conv > > http://www.gigatest.net/symmetricom%20TT&M/GPS%20&%20Time%20Code%20Instrumentation/ds_gps_antenna.pdf > 73 > KJ6UHN Alex > > > On 4/30/2015 9:50 AM, Tom Van Baak wrote: > >> I received this email. Anyone have a good answer? >> Thanks, >> /tvb >> >> ---------- >> Someone on ebay advised me to contact your website in hopes that someone >> in your organization can help me with my TrueTime model AL-AK GPS Receiver. >> I need to send it to someone so that they can check it to see if it works >> and can track Satellites. This receiver has the onboard up/down convertor >> board that changes the receiver input frequency which is set at 4.092 MHz. >> I don't have the needed down converter at the antenna. I bought this >> receiver on ebay from someone who told me that he doesn't have the down >> converter as well and can't figure out how to get it to work at 1575.42 >> MHz. He also didn't know if this receiver can be setup for a 1575.42 MHz by >> removing the onboard converter and changing some DIP switches. If one of >> your members can at least check out the receiver at 4.092 MHz for satellite >> tracking That would be a big help ... >> ---------- >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
