[TenTec] Totally tricked out Omni VI+ On ebay

Sun Mar 10 10:15:54 EDT 2013

Bob:
Thanks! Your explanation was a great help for me to understand the 
history and development of the Omni VI series radios. I knew that ripple 
was a design criteria by engineers but was unaware that the Inrad 
filters were higher. I will search the net and find the info you 
referenced in the last paragraph. I have been back operating after a 10 
year absence while my son played baseball. He graduated about a year 
ago. I have been slowly repairing my older TenTec qrp and cw gear to 
fund my radio account.
Thanks again for your time and insight.
73
Jack WN5A

On 3/9/2013 7:32 PM, Bob McGraw - K4TAX wrote:
> 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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