Comments on the Omni V, Omni VI, and Omni VI+
Editorial by Allan Taylor, K7GT
The Omni V was a first attempt at microprocessor
controlled radio. It was only partially successful. Nonstandard computer
interface, but a pretty good CW radio, etc. Fixed offset/sidetone at 600 Hz.
Omni VI (original) improves considerably on the V. Great computer interface.
Both the V and VI are major breaks from the early PTO-style radios (Omni A, Omni
D from either A or B series, Omni C ('C-series'), Corsair, and Corsair II.
So the tuning is much finer being something like 5 or 6 kHz per rev instead of
18 kHz/rev. Stability is better, too, although warm up still takes a few
minutes. The PTO radios take 1/2 hour or more while the V and VI take 5-10 and
then are settled down. Omni V is the 562, Omni VI is the 563.
The Omni VI+ came out in the late 90s and featured an additional filter position
at the first IF (9.0). Also, a DSP NR was added (and works well, although not
really equivalent to a Timewave 599ZX...). The VI+ was numbered as the 564.
Shortly after the + came out, TT offered three options to upgrade the Omni VIs
out there (and there were many). The first two options were equivalent and
amounted to adding the DSP NR. One was factory installed, the other
user/owner-installed. Option 3 had an additional position in the first IF and so
is essentially equivalent to theOmni VI+ (564) but still just says OmniVI on the
front panel. The option 3 was only done in the factory as it required replacing
two boards and the front panel. It cost $275, as I recall.
Some folks make a big deal as to whether a radio is a VI/opt3 or a VI+. As
far as I am concerned, they are equivalent. If anything, the opt3 radio
has a better CW note.
The Omni VI class radios have had a so-called microchirp to some degree or
another. A W9 (W9AC??) did a major study on rooting it out. A common fix
for the mostly CW op, though, is to replace the main SSB filter (the 2.4 at 9.0
MHz) with an INRAD 754 (2.8 kHz at 9.0 MHz). Its slightly wider bandpass keeps
the CW signal from crossing the knee of the filter and its phasing quirks which
cause (apparently) the microchirp.
I have two Omni VIs with the option 3 upgrade. They are great radios. I have
chosen to stick with them rather than upgrade to the Orion. One of them has been
advertised for sale a few weeks/month ago but no takers at my asking price of
$1100 w/o filters or p.s. I will keep it as a spare rather than give it away.
A few other thoughts. The older PTO rigs have some quirks to be sure (AGC
stinks, etc.) but my Corsair II has received many, many unsolicited favorable
comments on its CW tone quality. A Corsair II (model 561) can be found for about
$400 in reasonable condition and are a great buy for non-contest operating.
73, K7GT
almost a Tentec collector...