Thanks to those who contacted me off-list... the information was very
helpful.
I have learned (from Ten-Tec) that the 9.0033 Mhz crystal and padding
capacitor WAS factory installed and was a factory mod that was added after
the schematic was drawn. Another list member (the ham I originally
purchased my Omni VI from) sent me a scan of an 'updated' manual from
Ten-Tec that he had not sent me because he ran into wrong information in it
(he did include the original manual with the unit). Turns out that the
instructions for aligning the BFO freqs in that manual are WRONG... they
differ from the manual I have AND they do not correspond to either my
schematic OR the schematic in the newer manual. Don Prouty at Ten-Tec
mentioned that there are some incorrect versions of the manual out there.
I have added a 16pf cap in parallel with C12 and now USB aligns correctly.
However, I am still dinking around with CW. I've added another 56pF cap in
parallel with the original padding cap and am still about 900 Hz high on the
BFO freq, so I picked up a 220pF cap to replace these caps in the thought
that one cap is probably less subject to any drift than two.
Of course, I wonder why it is that my replacement ICM-supplied USB crystal,
at 9.003000 Mhz, is 'harder' to swing to a lower freq with less required
swing than the original Ten-Tec-supplied 9.003300 Mhz? I'm assuming that
the same quality that gives the ICM crystal more stability ('Q'?) also makes
it harder to warp. Is that correct?
Also, I want to align FSK Mark and Space before I button everything back up
(I want to set the correct BFO freqs for these modes even though I'll
probably never use 'em). The manual sez that I need between +2v and +12v
for MARK and between 0v and -15v for SPACE. Can I generate these by using a
9v battery into an RCA cord?
Finally... does anyone know what effect varying the BFO freq has on the
signal? If the BFO freq isn't at the spec freq, does that mean my
transmitted signal is off by that amount, or does the BFO adjustment act in
the same way the passband tuning knob does (if the BFO freq isn't set
correctly, then the IF is shifted when the PBT control is centered)?
- jgc
John Clifford KD7KGX
Heathkit HW-9 WARC/HFT-9/HM-9
Elecraft K2 #1678 /KSB2/KIO2/KBT2/KAT2/KNB2/KAF2/KPA100
Ten-Tec Omni VI/Opt1
email: kd7kgx@arrl.net
> -----Original Message-----
> From: tentec-admin@contesting.com [mailto:tentec-admin@contesting.com]On
> Behalf Of Michael Melland
> Sent: Thursday, November 14, 2002 8:55 AM
> To: forsale-swap@mailman.qth.net
> Cc: tentec@contesting.com
> Subject: [TenTec] FS: Ten-Tec Centaur Amplifier - Like New
>
>
> Having just purchased another item I must now sell my
> Ten-Tec Centaur amplifier. The amplifier is about 3 years
> old and is in perfect condition. I am the original owner
> (non-smoker). The amp has been very sparingly used and
> probably has less then 5 hours total "on" time on it.
> Much less transmit time...
>
> The Centaur utilizes 3 each Svetlana ceramic based 811A
> tubes and it is wired to operate on 120 volts. It draws
> about 11 amps of current at 120 volts max. and makes 600
> watts output +/- depending on antenna match and the band
> from 160 through 10 meters (WARC bands included). The
> amplifier loads easily and is easy to tune. Another BIG
> plus is that the amp will interface with any radio however
> it is designed to do QSK with Ten-Tec products using their
> usual EN OUT hook-up. 811A tubes are still economical and
> easy to find should you ever need replacement. I believe I
> have the original packaging for the amp and the manual is
> also included. The amp originally sold for $750 plus
> shipping and I am asking $600 plus shipping. There is not
> a mark on the amp and it is in "as new" condition.
>
> If interested please email.... digital pics available on
> request.
>
>
> Regards,
>
> Mike
>
> --
> Michael Melland, W9WIS
> Winneconne, WI USA
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> TenTec@contesting.com
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