Hi,
I had the urge to order now, but am holding off. Why? Though
I trust the Ten Tec engineers to "do good", I would like to
see it first, hi. On another forum, Adam, VA7OJ/AB4OJ, has
written of design criteria which he suggests be followed:
"1. Ham bands only coverage."
The "main" rcvr of the Orion is of this sort.
"2. Relay-switched preselection filters with
large, high-Q inductors"
The TT RX-340 has these in half-octave steps;
the Orion, don't yet know.
"3. A passive 1st mixer."
I have no idea what a "passive" mixer could be!
Mixers need LO input power, and a good amount
of it at that, like at least +10 dBm. Per Ten
Tec, the RX-340 high level diode-ring 1st mixer
is essential to provide high 2nd and 3rd-order
intercept points during the conversion to the
first IF frequency.
"4. A purely passive pre-mixer signal path (no RF amplifier)"
The TT RX-340 places a switch selectable +10dB
gain RF preamp immediately following the bank
of 8 half-octave bandpass filters. This preamp/
bypass/attenuator circuit is followed by another
set of 6 FET amps in push-pull; these feed into
the 1st mixer. What will the Orion have as the
front end?
" 5. That great old trick used to such effect in
the Ten-Tec Omni V/VI and the Icom IC-740: a
divided-down VHF synthesizer".
The first LO synthesizer in the RX-340 is a three
loop architecture; the first loop covering 80
to 99.6 MHz at VHF, dividing down from there.
The Orion, unknown just now.
I want to believe that the Ten Tec engineers on the Orion are
completely familiar with the recent textbook also referenced
by Adam in his note:
""HF Radio Systems & Circuits", Sabin & Schoenike,
editors. Noble, 1998.
This textbook was written by members of the
Engineering Staff, Collins Divisions, Rockwell Corporation."
Per Adam, one presumes that "the WAY" to do it
has been presented in that text, hi. Adam says others have
been preaching the truth for many years: "Dr Ulrich Rodhe,
KA2WEU, has been religiously preaching about
this in print for a long time.....
His first articles appeared in Ham Radio Magazine
in the late 70's and 80's. Rohde also published
many articles on the importance of IMD in switching
diodes, and filter switching and so on..."
So, I am really anticipating great things in the
new Orion from Ten Tec. I want them to reach their
goal as stated on the TT Orion web page:
"The Ten-Tec ORION represents an entirely new concept in
high-performance HF transceivers. Our goal with this new
groundbreaking design is to deliver the finest performance
level to date from an amateur transceiver."
I am anxiously awaiting more information!!
73, Jim KH7M
Impatient on Kauai!
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