[600MRG] U3S with T/R relay

[Hans Summers]

Hi Ed


> Note that accurate time (<1 sec error) is required for WSPR and other WSJT
> modes.  I use a NIST source from the internet but am planning to convert to
> GPS.
>

WSPR decodes successfully with +/- 4 seconds error. Even +/- 5 seconds, at
the outside limit. I believe that since part of the transmission is
"chopped off" by the end of the received audio file, even though it can
decode, there must be some small sacrifice because there are less redundant
data for the error correction algorithms to work with.

The Ultmate3S kit accepts 1pps a serial data from a GPS module, which is
used to discipline the time and frequency. You can use any GPS module with
1pps and serial data, but QRP Labs also have a $23 GPS receiver kit that
includes voltage regulator, onboard patch antenna, level conversion (to 5V
logic) and three LED indicators. See http://qrp-labs.com/qlg1 . This GPS
receiver is extremely sensitive by design, due to the large ground-plane
under the patch antenna. Even at 1575MHz (GPS frequencies) nothing beats
the physics and a large antenna farm (the large PCB, in this case!). I get
reports from all over, universally good, that it works indoors, it works in
the basement, it works everywhere. Some people have fun trying to STOP it
working, e.g. by covering it in a metal bread baking tray, usually with
only limited success! A quote from the November QST review of the
Ultimate3S: "The GPS kits were easy to assemble and were extremely
sensitive. WB8IMY's GPS unit achieved satellite lock within 2 minutes after
applying power, despite being inside an aluminium-sided house."

73 Hans G0UPL
http://qrp-labs.com