[TenTec] RE: Confusion About the 563 and 564

Robert & Linda McGraw K4TAX RMcGraw@Blomand.Net
Wed, 11 Sep 2002 19:35:11 -0500

Good points and well documented.

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".
> so many Omni VI's and VI='s now on the used market folks want to know
> 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
> transceiver (but we will leave that for another time.)
>  In July 1997 my Omni VI was returned to TenTec for the "Option III
> 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
> 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
> 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
> eventually "cooks out" and will not hold frequency tolerances well. Try
> aligning one and getting it to hold frequency.  The TXCO fixes that
> --The later 564's use slightly different BFO crystal frequencies (9.0003
> 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
> 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
> 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
> 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
> 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
> II.
> All for now.
> 73 de N1LQ-Dave
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