[TenTec] Omni VI Plus freq. readout
Gary Hoffman
Gary Hoffman" <ghoffman@spacetech.com
Thu, 3 Oct 2002 20:38:04 -0400
I must say that I agree that we are increasingly finding ourselves in
a world devoid of tolerance. My suggestion is that, while we can't
fix the whole world, we try to set a good example here.
73 de Gary, AA2IZ
----- Original Message -----
From: "David Hammond" <dhhdeh@concentric.net>
To: "tentec reflector" <tentec@contesting.com>; "Robert & Linda McGraw
K4TAX" <RMcGraw@Blomand.Net>
Sent: Wednesday, October 02, 2002 11:42 PM
Subject: Re: [TenTec] Omni VI Plus freq. readout
> Bob,
>
> Your questions #1 and #2 have merit, no question about it.
>
> The third however reflects more on you than me and is really uncalled
for.
>
> It helps to prove my comment on growing intolerance for opinions or
comments
> that run to the contrary on this reflector.
>
> I learned long ago about "P'n" contests.
>
> Thanks for helping to prove my point.
>
> N1LQ-Dave
>
>
>
>
> ----- Original Message -----
> From: "Robert & Linda McGraw K4TAX" <RMcGraw@Blomand.Net>
> To: "David Hammond" <dhhdeh@concentric.net>; "tentec reflector"
> <tentec@contesting.com>
> Sent: Wednesday, October 02, 2002 10:22 PM
> Subject: Re: [TenTec] Omni VI Plus freq. readout
>
>
> > Three questions:
> >
> > 1. When was the Onmi designed and when was the IC 756 Pro II designed?
> > 2. Do you think time base and design technology stood still during this
> > period?
> > 3. Does the tuning knob on your radio work and do you know how to
> correctly
> > use it?
> >
> > >From the Tentec Omni VI+ manual:
> > FREQUENCY ACCURACY +/- 50 Hz @ 25 degrees C. (NOTE: the frequency
will
> > shift noticeably for 1 - 2 minutes while the oven heats up when first
> > turned on. Leave DC power connected to the rear panel el eliminate this
> > turn-on drift).
> >
> > And I see all the P'n and Moanin' over 10 Hz.
> >
> > I use my Omni VI+ on 20M PSK31 and yes I see many signals in the 500 Hz
> > passband. Never have a problem finding my schedule or frequency. Guess
> my
> > tuning knob works and I know how to use it.
> >
> >
> > 73
> > Bob, K4TAX
> >
> > ----- Original Message -----
> > From: "David Hammond" <dhhdeh@concentric.net>
> > To: "tentec reflector" <tentec@contesting.com>
> > Sent: Wednesday, October 02, 2002 8:58 PM
> > Subject: [TenTec] Omni VI Plus freq. readout
> >
> >
> > > Hi Everyone,
> > >
> > > Once again I am compelled to comment on this thread having spent a lot
> of
> > > time seeking to improve this very specific Omni VI problem. It's real
> and
> > it
> > > does exist.
> > >
> > > After 5 1/2 years of Omni VI ownership (prior to selling it this past
> > > Spring), I chased improved frequency readout accuracy on this radio
and
> > came
> > > up with the following conclusions. My Omni VI suffered from both
> frequency
> > > repeatability and accuracy problems considerably greater than other
> > > transceivers I have owned. In fairness to Ten Tec though, the Omni VI
> > and
> > > VI+ were never spec'ed to super-precise frequency accuracy.
Nevertheless
> > > this problem bugged the heck out of me over time. So I embarked on a
> > series
> > > of modifications seeking an improvement. Funny, I thought that
> > > experimentation was in the true spirit of ham radio from days gone by.
> > > Anyway......
> > >
> > > The frequency repeatability problem was vastly improved if not solved
> > > outright by substituting the 2ppm TCXO for the original crystal oven
in
> > the
> > > reference oscillator. A tremendous modification for older Omni VI's.
> About
> > > $40 and hours work. As I have said before, it is the best change Ten
> Tec
> > > has come up with for the Omni VI and VI+. While many crystals do
exist
> in
> > > the radio's L/O circuit, unlike in the Omni V, the VI's L/O crystals
are
> > > tied to the reference oscillator and cannot be individually trimmed
per
> > se,
> > > for improved frequency accuracy. Small deviations do exist from band
to
> > band
> > > but are not a real bother IMO.
> > >
> > > Th real culprits in the Omni VI are the BFO crystals located on the
> board
> > > directly under the in-board speaker. This circuit is subject to
> > significant
> > > thermal drift coming and going in response to rig-generated heat and
> even
> > > changes in ambient room or Wx temperature. Attempting to fix this
> problem
> > I
> > > first removed the speaker to allow for convective cooling up through
the
> > > speaker grill. Good but not great results. Then I substituted higher
> > > quality ceramic trimmers for the USB and LSB trimmers. No real
> > improvement.
> > > Finally I ordered custom built USB and LSB BFO crystals from ICM in
> > > Oklahoma. About $70 and an hour's work later, I had them installed.
> This
> > > change removed about 99.5% of the thermal drift resulting in better
than
> > > spec'ed display accuracy. The BFO circuit is the culprit in this rig
> > > causing the problem with frequency accuracy. It is noticeable in SSB
> over
> > > periods of extended TX activity. New custom crystals and its just
about
> > > gone.
> > >
> > > I must join with Adam and George in telling you that my new IC 756 Pro
> II
> > > has provided me with amazing frequency accuracy and repeatability.
And
> to
> > > those of you commenting that it does not matter I beg to differ. It
> > matters
> > > to many of us a whole lot. I simply got sick and tired of always being
> off
> > > everyone else's frequency. It also matters if you want to work MARS.
> Check
> > > out the MARS rig requirements of late.
> > >
> > > I will also add that some of the snide comments including "sell your
> Omni
> > > and keep you Jap rig then you won't be so stressed out" once again
> > > demonstrate to me the developing intolerance of some on this list.
> > > Regrettable.
> > >
> > > I have both ICOM and Ten Tec gear here now but hold no blind
allegiance
> to
> > > any manufacturer. Competition breeds the best product for us all. To
> each
> > > his own. This specific problem was/is important to me and many others
> who
> > I
> > > have spoken with but who care not to comment on the reflector.
> > >
> > > And on a final unrelated note, I wish TT would put some good quality
> Orion
> > > photos on the TT Web site. It needs to be seen better than is being
> > shown.
> > >
> > > 73 de N1LQ-Dave
> > >
> > >
> > > _______________________________________________
> > > TenTec mailing list
> > > TenTec@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/tentec
> >
> >
> >
>
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