[TenTec] RE: Confusion About the 563 and 564

David Hammond dhhdeh@concentric.net
Wed, 11 Sep 2002 20:14:02 -0400

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

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
--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

All for now.

73 de N1LQ-Dave