[TenTec] Totally tricked out Omni VI+ On ebay

[Bob McGraw - K4TAX]

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 at sbcglobal.net>
To: "Discussion of Ten-Tec Equipment" <tentec at 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 at gmail.com>
>> To: "Discussion of Ten-Tec Equipment" <tentec at 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 at 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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>>
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