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Re: [TenTec] Totally tricked out Omni VI+ On ebay

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] Totally tricked out Omni VI+ On ebay
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 9 Mar 2013 19:32:11 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Well Jack, I've owned two of them and repaired several for other folks. I'm no expert! Just a fixer with one slated to arrive on the bench next week.

I don't have specifics about the change between the oven model which was used in my first Omni VI Plus and the TXCO model which was my later Omni VI Plus. The manual I have is 1st printing dated 1/97. It shows the oven crystal. While there's nothing wrong with this implementation, it simply requires DC power to be applied all the time, even though the radio is off, to maintain temperature and stability. Otherwise, it takes a few minutes for the crystal to come up to temperature and stabilize.

I see one or more postings referencing the TCXO which is 8/06 so we know it took place between 1997 and 2006. Otherwise, not very specific. I sold my last Omni VI Plus along with the original manual. Wish I'd kept a copy.

Here's a link that provides additional information. http://tentecwiki.org/doku.php?id=563upgrade

The ripple across the top of the filters will or can make a noticeable difference in audio response. I understand the approach toward the INRAD filters were to move to a tighter filter which has steeper slopes and skirts as compared to the standard filters. There seems to be a trade-off in that with the steeper slopes, the carrier is further down on the slope of the filter and the audio response changes and the steeper slope design does contribute to some 3 dB to 6 dB ripple across the top of the filter curve. I have only used stock filters in my radios, but others have come across my bench with the INRAD filters.

As N1EU states " There are indeed differences. An early 563 and a late 564 are very different radios in many respects aside form the advertised feature differences. I've spent many hours of A/B comparisons of various vintages of Omni 6/6+ from 1992 to 2001. My conclusion is that any improvements in RX noise/birdies was subtle, if at all audible, and that the earliest units performed as well as the latest units." And Dave, N1LQ states, "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. Later 564's use significant amounts of SMT construction."

Hope this helps.

73
Bob, K4TAX





----- Original Message ----- From: "Jack Van Demark" <wn5a@sbcglobal.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, March 09, 2013 6:42 PM
Subject: Re: [TenTec] Totally tricked out Omni VI+ On ebay


Bob:
You seem extremely knowledgeable on the 6+. When did they have to switch to the TCXO's, about what year radio would have them instead of the crystal oven? That radio on eBay has all TenTec filters except the additional roofing filter and circuit board.
Do you use stock TenTec filters in your radios?.
What does the excessive ripple do to the receive audio?
Thanks  73
Jack WN5A

On 3/9/2013 4:37 PM, Bob McGraw - K4TAX wrote:
Nice looking older radio. Has the crystal oven where the later models had the TXCO. As to the INRAD filters, I find they have too much ripple across the top to suit my taste. Your mileage may vary.

73
Bob, K4TAX



----- Original Message ----- From: "Barry N1EU" <barry.n1eu@gmail.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, March 09, 2013 2:04 PM
Subject: Re: [TenTec] Totally tricked out Omni VI+ On ebay


Caution: if you don't want to deflate your high opinion of what an Omni 6+
is worth, don't look at the listing   ;-)

73,
Barry N1EU

On Sat, Mar 9, 2013 at 7:35 PM, Jack Van Demark <wn5a@sbcglobal.net> wrote:

Purely an FYI!
If you haven't seen it ,there is a totally tricked out Omni VI+ on eBay
that will go another couple of days. Wish I had more money in my radio
account. All filter slots filled and International radio roofing filter
kit installed.
73
Jack

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