[TenTec] Orion vs. RX-340 TT Rcvrs.

[Jim Reid]

I have been asked again recently to compare these
two for use by radio amateurs.

They are sitting here side by side.  In fact,  using N4PY
software,  the 340 can play the part of the sub-rcvr for
the Orion.  It is difficult to compare the two rcvrs,  as they
are different in design in the front end.  Both have "strong"
front ends as far as overload/dynamic range is concerned.
But the 340 front is fixed wider than the variable roofing
possible in the Orion.  However,  the RX-340 front end
is more "strong" than that of the Orion main rcvr;  e.g. the
340 has a guaranteed 3rd order IP: +25 dBm min, 
+30 dBm typ (preamp OFF);  Orion, +24 dBm typ,  with
5 kHz signal spacing, preamp OFF,  and no guarantee.
.
At my QTH here on this island,  there are nearly never any
strong signals heard;  only exception might be on
Field Day when one of the locals uses an Alpha at the
club station set up;  so far as I know, he does not use the
Alpha any other time of the year!

These rcvrs are equally sensitive,  but the S meter of the 340 is
MUCH better at reading actual signals,  even on down to
140 dBm as the meter seems accurately calibrated all the
way down as well as up to +80 dB over S9 !!  Of course,
I have never seen a signal that strong out here! I have checked
the low signal level behavior of the 340 using a precision
step attenuator;  the 340 S meter tracks very well and
accurately.  The strongest regular signals I can hear are
from WWVH here on Kauai.

WWVH's 10 kW transmitters are only about 11 miles on
West of me here on the South side of Kauai,  though there
is a low ridge between us.  On the 340,  the signal strength
from any of their 2.5, 5, 10 or 15 mHz antennas is only 
about 9+5 dB.  Of course,  this is as rcvd via my 80 meter
doublet antenna and Matchbox tuner still set to one of
amateur bands.

Another neat feature the 340 has over the Orion:  it
can be "locked" to an external frequency reference.  I
use a surplus Hewlett-Packard cell telephone node
GPS rcvr which is specifically designed to keep the
cell system on very exact GPS time sync.  Keeps the
340 "smack on",  and I can use that to accurately also
place the Orion "smack on".  I have re-set the TCXO
unit calibration within the Orion to be close to exact,
but it does have a warm up drift -- takes the Orion
TCXO an hour or so to settle down to where it is going to 
stay.  I have it set now such that the frequency read out
is within 10 cycles of exact at 10 MHz.  I will re-do
the calibration in a couple more months when I will
have had the Orion for a year or so.  "They" say
that at that time the TCXO will be over its' infant
drift characteristics.

These two radios are just different!  The 340 has only
the single wide front end roofing filter, a pair of 2-pole 16 kHz
crystal filters.

In the Orion,  you can select that filter,  all the way down
to only 250 Hz,  though I usually am using either the 2.4
for SSB,  or the 1 kHz for CW.  

The Orion has front end switched filters to isolate
each amateur HF band.  The 340 has 1/2 octave,
switched preselector filters; e.g. 2.5 to 4; 4 to 6; 6
to 9; 9 to 15 MHz,  etc.

The 340 will tune down to 50 kHz;  the Orion, down to
500 kHz.

Another big difference is the number of "handles" given
us on the Orion, and each adjustable via very intuitive
front panel control.  The 340 handles are not so obvious,
and frequent looks at the manual are needed at times, if
for example you want to change AGC programmed
characteristics. However,  the AGC thresholdd cannot
be adjusted in the 340,  while the hang,  decay,  and attack
can be.  (The AGC attack is NOT adjustable in the Orion but
Threshold can be and is very handy!).

For amateur radio HF use,  the Orion is "better" for most
things amateurs want to do.  But,  if you want absolutely
exact frequency and pretty good info on incoming signal
strength,  then the 340 is better.

Well,  anyway there are some comparisons between the
two.  One of the Ten Tec folks was quoted as responding
to the question about an RX-340 "type" rcvr ever being
offered in an amateur transceiver;  the answer was, 
approximately, "It would be way too costly for ham's since there
are many "commercial use" only features included not needed
by amateurs.  For example,  guaranteed group delay specs
all the way through the radio and several IF output ports
through the various stages of IF processing.

Hope of some use.

73,  Jim  KH7M