Stew Perry Topband Challenge - Spring
Call: K1LT
Operator(s): K1LT
Station: K1LT
Class: Single Op HP
QTH: EM89ps Ohio
Operating Time (hrs): 10:46
Radios: SO2R
Summary:
Total: QSOs = 436 Total Score = 1,489
Club: Mad River Radio Club
Comments:
Each time a 160 contest appears on the event horizon, I make some plan
to try to use my forever project. This time I discovered the 'system
on chip' FPGA development board I am using for the reincarnated phased
array does not have enough CPU horsepower to run three SDR receivers
simultaneously. Each software receiver processes the signal output by
the beam forming hardware in the FPGA. So the next step is to move
more of the SDR receiver into hardware.
Meanwhile, there is a 160 meter contest to operate. Since the spring
Stew is a more casual event, I didn't make any effort try to put the
north / south array to use.
I did repeat the trick I tried for the CQ 160 which is to operate full
duplex by using a Beverage "phased" with a sample of my transmitter
to
'null out' my transmit signal. Finding the proper amount of
attenuation and phase shift seems still to be somewhat magical, but
once set, it seems to stay aligned and it works. I am using an
N-connector equipped doohickey that looks like an oversize T-connector
except that there is no direct connection of the center conductor for
the 3rd port and that port telescopes allowing the amount of coupling
to change. The output of the sampling doohickey is further attenuated
by a 20db step attenuator and some resistive pads and phased shifted
by some coax. The amount of phase shift was determined using an
oscilloscope. The attenuated and phase shifted transmitter sample and
the desired Beverage signals are then summed by the nulling
contraption I previously used with a pair of verticals. The nulling
device allows fine tuning of the attenuation and phase shift to
maximize the null.
The result is I can listen to signals on one Beverage while I am
transmitting to within about 3 kHz plus or minus my run frequency.
One disadvantage of this scheme is that the Beverage is directive, so
I likely overlook signals not favored by that Beverage. The solution
to this issue is to build another nulling contraption and switch
between them as needed. Another disadvantage is there seems to be
some micro-arcing in my transmit antenna which causes broadband noise
if I transmit too long or with too much power which strongly suggests
a thermal cause for the micro-arcing. This problem may be harder to
solve although I know a couple of places to look for suspect
connections.
Like everyone else, I noticed that the nighttime was initially quiet
but got very noisy, peaking around midnight, and then quieted down
again. The was a very noticeable but short burst of European callers
at my sunset, with DR5X as my first European and IQ9UI my best DX for
many hours (17 points). Also I did not hear any DX activity prior to
sunset. DX seemed to come in small waves with no apparent bias
towards any region. I did not notice any Eu sunrise enhancement, but
maybe there was a lack of activity. The best eastward DX was SV3RF in
KM18 (18 points). I find it hard to believe that Greece is be so
distant.
The west coast seemed reasonable when they weren't buried in the
thunderstorm noise from the central US. I did not work anything west
of grids CN and CM. No VE7.
Somewhat after midnight, short hop signals acquired a very noticeable
auroral flutter which is strangely disturbing on 160. 160 signals are
supposed to fade, not flutter. The fluttery stuff seemed to last
about an hour.
I thought about staying up all night but with DST springing up and a
new, early take-the-kid-to-school schedule first thing Monday, I opted
for sleep. I stopped at 0700z and set the alarm for 1100z but woke up
before the alarm. The morning was surprisingly busy although most of
the contacts were for small points.
I made fewer contacts this year as compared to last year, mostly
because of the lack of DX. Conditions for the most part seemed
nominal, neither good nor bad, but there appeared to be no long-haul
propagation. The noise while it was present seemed more annoying that
normal given its magnitude, perhaps because it was very continuous.
The surprise not-a-multiplier was K8LT because the QSO was like
working myself. Gary is a college buddy and former coworked who moved
to the W1 district. We try to maintain out-of-district balance.
DX worked: 9A (2), DL (3), F (3), G (2), HI, I (2), KH6, KP2 (2), LY,
LZ, OK (2), OM, ON (2), OZ, PJ2, S5 (2), SM, SP (3), SV, UR (2), XE,
and ZF for a total of 22 entities. 37 DX QSOs compared to 71 last
year.
Equipment: K3S/100, P3, 8410 at 400 watts, K3/100, P3, homebrew SO2R
stuff, 2 phased array / SDR receiving systems, 12 Beverages (1 used
for many 2nd VFO QSOs), 'tee' antenna 60 feet tall over 75 radials.
Posted using 3830 Score Submittal Forms at: http://www.3830scores.com/
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