Les G3NFP Said:
Are you going to share the details of your well designed interface?
By the way most PSK operation in Europe takes place around 1838.15 as we
have no access to frequencies below 1810.
Presuming that you mean me here's the deal with my homebrewed digital
interface. I used the circuits found on WM2U's excellent PSK31 website at:
http://www.qsl.net/wm2u/psk31.html .
First of all I used real RG-174 for the cabling and soldered on metal cased
connector plugs and jacks. All the cabling goes through three split beads on
each end of the cable. All components are soldered onto a circuit board and
placed in an shielded aluminum enclosure. The components themselves came from
Mouser Electronics, not the Radio Shack junk. Between the fixed audio out from
my Yaesu FT-840 to computer soundcard input I used a 1:1 isolation transformer
and variable potentiometer, same with soundcard output to rig mic input. My
FT-840 does not have VOX so I also had to build a PTT circuit between the 9 pin
serial port on the computer and mic input plug. In this circuit I used an
opto-coupler.
This interface works very well on PSK31, MFSK16 and RTTY. I'm able to run 100
watts with a very narrow clean PSK31 signal, better then a -30 IMD and good on
air reports.
Also my radio station and computer are well grounded to prevent stray RF
problems. The ground system consists of four one inch diameter ten foot long
copper water pipes spaced 12 feet apart, plus thirty two sixty four foot
radials on the ground, plus one 1/4 wave radial for every band between 160 and
10 meters. The antenna is a switchable 160-10 meter doublet/tee vertical up at
40 feet and fed with 450 ohm window line to a balanced antenna tuner.
As far as digital DXing on 160 meters I realize that many other countries can't
operate below 1810 kc, so operate around 1838 kc. But with the recent tensions
on 160 meters here in the U.S. over failed band plans, I would not want to
operate around 1838 kc. Split would be the way to go, plus it's probably to
late now for any reliable across the pond PSK31 operation until next winter due
to rapidly building QRN levels. However MFSK16 and the new mode PSKFEC31 might
work?!
73 & GUD DX,
Thomas F. Giella, KN4LF
Retired Space & Atmospheric Weather Forecaster
Plant City, FL, USA
Grid Square EL87WX
SKYWARN Observer # HIL-249
SWFWMD Observer #574
PODX 070 PSK31 Member #349
Yaesu FT-840 & PSK31 News Group http://groups.yahoo.com/group/yaesu_ft840
10 & 6 Meter Propagation Beacon Network http://www.PropNET.org
Solar Space Weather & Geomagnetic Data Archive http://www.kn4lf.com/kn4lf5.htm
HF/MF Radio Propagation Theory Notes http://www.kn4lf.com/kn4lf8.htm
160-10 Meter Amateur Radio Resources & More http://www.kn4lf.com
Florida Space & Atmospheric Weather Institute http://www.kn4lf.com/fsawi.htm
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