New Claimed World and North American Distance Record (79.6km) and VUCC #1 for the 241GHz Amateur Radio Allocation
I'd like to claim what should be a new World and North American DX
record for the 241GHz band.
Last night, W2SZ/4 worked WA1ZMS/4 on 241GHz at a distance of
79.6km using slow speed CW (QRSS).
Detais of the QSO
Date: Feb 17th, 2004
W2SZ/4 in FM07fm (37-31-00N 79-30-35W)
WA1ZMS/4 in EM96wx (36-59-28N 80-07-17W)
The weather at the W2SZ/4 QTH was:
Dew Point: -26C
Relative Humidity: 22%
Station pressure: 884mb
Atmospheric loss: 0.273dB/km
The weather at the WA1ZMS/4 QTH was:
Dew Point: -16.1C
Relative Humidity: 53%
Station pressure: 932mb
Atmospheric loss: 0.681dB/km
Pete, W4WWQ was the CW op at W2SZ/4. WA1ZMS/4 was the op of his own
station at the EM96 QTH. Both ends of the QSO used Spectran software to
aid in receiving the slow speed CW at a rate of approximately 1 second
per "dot", 3 seconds per "dash".
The entire QSO took well over an hour to complete with both
stations having to send the exchanges several times. Some portions of
the CW were copied by ear, but the DSP software came through in the
end to help make the QSO happen.
Both stations used new Wenzel Ultra-Low-Noise 5MHz reference
oscillators as the phase-locking frequency references. Short-term
stability on the order of 4 x 10-13 is required to keep the signals
within a 1Hz filter bandwidth of the demodulating software.
The stations were keyed using Island Keyers with custom QRSS
firmware from Charles Olsen, WB9KZY.
This QSO is also the 5th grid needed for the ARRL VUCC award for
the 241GHz band for W2SZ. This claim should be the very first VUCC for
that band and has taken many months of hard work and many VERY
cold-night DX-peditions to make it all happen. This latest DX record
of 79.6km occurred on our fourth attempt, so we were not without our
Brian Justin, WA1ZMS
For more information on Brian's 241GHz experiments you can also take a
look at the following:
241GHz Station Details
Here are some details of the 241GHz station
as it has been modified for the latest DX
The transmitter is based on a 40mW 80.666GHz Gunn oscillator driving a
anti-parallel Schotkey GaAs diode X3 multiplier (the original design
of the multiplier was by Virginia Diodes Inc). The resulting 241GHz
output power is a measured -1dBm.
The receiver is based on a modification of the X3 TX multiplier. By
adding a DC/IF return port it converts the multiplier into a harmonic
mixer. Each station's TX frequencies are offset which allows the use
of a tunable RX IF of around 439MHz.
New homebrew 30cm parabolic reflectors with Cassegrain feed system
using true hyperbolic sub-reflectors. The machining of the curved
surfaces was done with help from a local machinist. The feed is a
W2IMU style dual-mode horn with a step transition from rectangular
WR-3 waveguide. Antenna gain is around 53dB (rough measurement).
New homebrew direct synthesizers have replaced the former 5th
over-tone VHF crystal oscillators. The direct synthesizers are now fed
by 5MHz Ultra Low Noise reference OCXOs from Wenzel. CW keying is by
FSK'ing the 5MHz OCXOs. The close-in phase noise of multiplied 5MHz
OCXO is many times better than even the best VHF crystal
Station Block Diagram
Schematic diagram showing design of direct synthesizer
used in the station LO chain. This circuit replaces the
typical VHF crystal oscillator used in the Freq. West
Images and pictures
241GHz 30cm dish
The view from Apple Orchard, FM07fm in the direction of EM96.
The view from EM96wx looking back to Apple Orchard Mtn.
Distance is 79.6km.
Ice on the tripod at Apple Orchard the night of the
79.6km DX QSO. Temp outside was 17degs F.
Photo showing one of the new Wenzel Ultra-Low-Noise 5Mhz reference
oscillators before being installed in custom milled sub-chassis.
Phase noise of this oscillator is -120dBc/Hz at 1Hz offset, and
-150dBc/Hz at 10Hz offset!
5Mhz reference oscillator in its final outer chassis.
Coleman brand cooler that housed Wenzel reference oscillator and gell
cell batteries. These oscilaltors are always kept running and have
never been powered down over the past several months. This helps reduce
oscillator re-trace issues.
Laptop PC screen capture showing the signal as "heard" in EM96.
You can see Morse characters "W" and "A" of WA1ZMS being received.
DSP filter bandwidth set to 1.3Hz.
This images shows the W2SZ end of the QSO as viewed with Spectran.
CW text of "2SZ" can be seen. The 75Hz of frequency drift shown
is due to the Icom R-7000 IF receiver having hot air blown on it
while Pete, W4WWQ, was operating inside his vehicle.
Signals were not always good. It took over 1 hour to make a valid two-way