Good points and well documented.
73
Bob, K4TAX
----- Original Message -----
From: "David Hammond" <dhhdeh@concentric.net>
To: "tentec reflector" <tentec@contesting.com>
Sent: Wednesday, September 11, 2002 7:14 PM
Subject: [TenTec] RE: Confusion About the 563 and 564
> Hi Everyone,
>
> First let me comment that I infrequently contribute to this reflector
> anymore because of my perception of an increasing lack of tolerance on
> certain subjects that folks want to bring up.
> .
> IMO the recent questions regarding the 563 and 564 are well worth
> understanding and commenting on and is not just "beating a dead horse".
With
> so many Omni VI's and VI='s now on the used market folks want to know
what's
> up.
>
> I bought my Omni VI 563 in November 1996, one of the last Omni VI's that
> were made. I sold it this past June. Being initially disappointed in the
> prospects of the forthcoming Orion I bought an Icom 756 Pro II, a
fantastic
> transceiver (but we will leave that for another time.)
>
> In July 1997 my Omni VI was returned to TenTec for the "Option III
upgrade"
> which gave the Omni VI the electrical performance of an Omni VI+. Since
> 1997 the newer Omni VI+'s underwent many minor factory changes to
eliminate
> problems and improve performance from earlier productions runs. IMO the
> cumulative impact of these minor changes is significant.
>
> Here are some of the notable things I know of in no particular order:
>
> --The silk-screening of the 564 has the "Plus" on it (dah...)
> --The 564 has a different font silk-screened on the input keys from the
563
> keypad. Noticeable side by side
> --The later 564's replaced the crystal oven with a 2ppm TCXO on the logic
> board, probably the best enhancement TT did to this radio. The crystal
oven
> eventually "cooks out" and will not hold frequency tolerances well. Try
> aligning one and getting it to hold frequency. The TXCO fixes that
problem.
> --The later 564's use slightly different BFO crystal frequencies (9.0003
USB
> and 9.0033LSB/CW) from earlier units, apparently to improve the alleged CW
> key click problem
> --The later 564's have certain changes to top and bottom foil grounding on
> certain boards to improve 10M birdies which are a major problem with this
> rig.
> --The BPF filter on later 564's has a broadcast band mod to improve
intermod
> in the presence of strong local AM BCB or SW signals. Night and Day
> difference on my rig.
> ---An aftermarket mod from INRAD is available to improve the SSB audio
> response involving a swap of two component values. This became a
> semi-approved factory mod. Stock audio is degraded by passing through
the
> DSP chip when DSP is not engaged
> --Later 564's use significant amounts of SMT construction
>
> There are others. I just have forgotten them.
>
> If there is no difference in the 563 Upgrade III and a 564 why did TT
change
> the model number, name and affix a special label on the back of Omni VI
> upgrades to distinguish them from the Omni VI+?
>
> There are indeed differences. An early 563 and a late 564 are very
different
> radios in many respects aside form the advertised feature differences.
>
> IMO to advertise a 563 upgrade III as a 564 as I have seen done on the
> auction sights is misleading.
>
> As for me, I still have my Omni V.9 using Carl's fabulous processor chip
> upgrade. Man what receive audio! It stays in this shack backing up the
Pro
> II.
>
> All for now.
>
> 73 de N1LQ-Dave
>
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