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
>
>
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