I found out why my RFTG-0 unit was AFU, turns out I must have damaged a resistor causing the EFC voltage to wonder from one extreme to another. Replaced the damaged part and it seems to be working again
From a cold start it takes less than 20 minutes for the NO GPS to go off using a decent outdoor antenna.
Stability seems ok for my needs. After running overnight and sitting directly under a ceiling fan and the AC cycling the short term frequency deviates less than .0004Hz according to my 53131A.
Still getting gibberish from com port. Tried several different Prolific RS232 to USB adapters on 2 different PC's, Win 7 and XP. Must be something real obvious that I am missing and just dont see it ?
Here's the pinout of J6 if anyone is interested:
J6 goes to U37, U38, U39 (75176 Differential Bus Transceiver)
J6.1 --- U38.6
J6.2 --- NC
J6.3 --- GND
J6.4 --- U39.6
J6.5 --- U37.6
J6.6 --- U38.7
J6.7 --- GND
J6.8 --- U39.7
J6.9 --- U37.7
Hi N8AUM -
How did you damage that resistor? I am curious if it was via some external connector, and if so what the cautionary note on that is.
Here is the RS-422 set-up that I have. Note that I am connected to
J8, not J6. J8 is the port where you can send commands and monitor status. J6 also has an RS-422 interface, which outputs a time string, but I have not seen any info on what commands you
can send there. It may be a read-only thing.
I am using a Gearmo USB to RS-485/RS-422 Converter, model # US-485422.
Link to product on Gearmo.com:
http://www.gearmo.com/shop/usb-to-rs485-rs422-converter-with-ftdi-chip/Link to product on Amazon:
http://www.amazon.com/gp/product/B005CPLOVWThe Gearmo uses an FTDI chip, and they have a download link to the FTDI drivers on their web site. You can also just grab the FTDI drivers from their web site (ftdichip.com). I believe the FTDI chip is RS232RL. It's also possible that the drivers can be installed via Windows Update; I couldn't tell if that was the case because I already had the driver installed on my machine.
The Gearmo product comes with a little terminal board connected to a DB9-male connector. The terminal strip connections are labelled and match the names below (T/R+, RXD+, etc.). Note that the Gearmo documentation, and labels on the terminal strip, refer to "TXD" as "T/R".
Gearmo RTFG-u/REF0/1 J8
-------- ----------------
1 (T/R+) --> 4 (RX+)
2 (T/R-) --> 8 (RX-)
3 (RXD+) <-- 5 (TX+)
4 (RXD-) <-- 9 (TX-)
5 (GND) --- 7 (GND)
I am using the little DB9-to-terminal strip adapter that comes with the Gearmo to connect up to another terminal strip to DB9 adapter and swap the wiring. I can't recommend the terminals trip adapter that I bought for that, however, as I ended up having to dremel off some bits to get it to fit. I'll replace all this with a custom cable when the parts arrive next week.
The unit came up set for 9600/N/8/1 when it first booted. There appears to be a command to change the baud rate, but I haven't tried that.