[CQ-Contest] SO2R Question

Leigh S. Jones kr6x at kr6x.com
Wed Feb 27 15:08:36 EST 2002

SO2R implies all of the following:
1) simultaneous receive on any two frequencies
2) simultaneous receive on one band while transmitting on any another
band with minimal interference
3) instant (milliseconds) change of transmitting band, i.e. switching
from transmit on frequency A/receive on frequency B on another band
to receive on frequency A/transmit on frequency B in the snap of a
4) uncompromised control of the first 3 features in this list
(switching capability)

It's most likely to be achieved when: no antennas share coaxial
cables, generally no antennas are multi-band.  It's easier to achieve
when using 2 or more amplifiers and 2 or more transceivers forming 2
or more complete station setups controlled by a single computer.  The
capability is compromised when using 1 auto-tune amplifier such as an
Alpha 77 because there is too much tune-up delay time to allow
bandswitching from the (former) transmit band to the (new) target band
before another CQ is issued from the target frequency or another
station answers the CQ on the target frequence (results in delays that
prevent the effective use of the technology).  Excessive delays are
usually involved when switching/controlling the main transmitter from
the transceiver frequency to a secondary receiver frequency when using
most dual receive rigs such as the TS950SDX.  The goal is to be able
to send your exchange on one band (i.e., with the <F3> key) while
simultaneously tuning in a CQ on the second rig, and to check for
dupes and be prepared to call stations on the second rig as soon as
your exchange has completed on the first band -- with no conscious
effort involved in making band changes and no delays or inter-station
interference introduced by equipment/antenna limitations.  This is a
daunting problem when operating with high power -- often requiring
special filters to reject cross-band RF, but is usually attainable at
low power when using 2 transceivers and monobanders if some effort is
taken to isolate antennas, coaxial cables, and station grounds.  Some
have succeeded even at high power levels even when using a single
tower; the goal is probably unattainable on 10-15-20M with a
tribander -- although a tribander that uses separate feedlines on each
band might allow it (I think some Force 12 antennas allow this, for

Frankly, I hesitate to provide a definition of SO2R -- too many
contesters who do not have the capability (both station capability and
knack for operation) would like to see SO2R scores categorized
differently from basic single operator scores so that their own
efforts will better shine.  I did extensive SO2R operation from W6HX
in ARRL DX contests and SS contests during the 1970's, and found an
advantage.  However, I'd have to point out that SO2R operation can be
extremely fatiguing expecially when compared to maintaining a single
run frequency.  Too much SO2R operation without sleep in a 48 hour
contest can quickly result in the capability of the operator degrading
dramatically; the SO2R operator has to pace himself, just as a long
distance runner would.

Also, limited SO2R capability can provide great score benefits.  By
limited capability, I mean SO2R with problems preventing full use of
the technology such as band combinations on which the capability is
absent due to shared feedlines or cross-band interference. To explain
this, I'd mention that it might be that SO2R on the low bands provides
a greater improvement in effficiency than the same capability on the
high bands during many contests.  This is due to the change in the mix
between "running" and S&P operation and in the relatively high
opportunity for duplicate contacts on the low bands.  During DX
contests in particular, operating SO2R on the more active high bands
is potentially much more fatiguing than on the less active low bands.
During a quick contest like the NA Sprint (which has no 15 and 10
meter activity), the benefit of SO2R can be maintained for the full
length of the contest.  In much of the US there is significant daytime
40M activity during domestic contests, and this could allow one 40M
rig and one 10-15-20M rig to be used for SO2R. These effects combined
could mean, for example, that a station with a tribander on one
coaxial cable, and separate coaxial cables for the 40M and 80/160M
antennas, might effectively gain a great deal of the advantage that is
possible from SO2R operation across a wide spectrum of contests (true
SO2R capability on 20M and below, plus relaxed runs on the higher

----- Original Message -----
From: "Ford Peterson" <ford at cmgate.com>
To: "Contest reflector" <CQ-Contest at contesting.com>
Sent: Wednesday, February 27, 2002 12:06 PM
Subject: [CQ-Contest] SO2R Question

> Is a radio capable of operation on two separate frequencies (dual
> considered 2 radios for SO2R?
> If I understand it correctly, a dual receiver radio is not SO2R.  So
if I
> use the receiver on a second radio, which just happens to be a
> am I SO2R or not?
> Ford-N0FP
> ford at cmgate.com
> _______________________________________________
> CQ-Contest mailing list
> CQ-Contest at contesting.com
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