[TenTec] Fair Market Price for Omni VI+ will all filters&matching PS ?

[Bob McGraw - K4TAX]

Yes, I do have documentation on the enhancements.  Unfortunately of the 6 or 
7 radios it seems that they all do not exhibit the same exact issues and 
therefore I've found each requires different approaches and methods to clear 
up the birdies.

On the birdie issue, I start with a 1/2" ID #43 bead which is split in two 
halves.  I can then put it around each cable, one end then the other, and 
observe the difference.  Then move on to another one.  Once I've found the 
optimum for that specific radio I can then go in and in some cases I need to 
re-make the ribbon cables as they need to be a bit longer to allow the new 
cable to make at least one turn through the bead and include a bead in the 
correct place with the new cable configuration.  This must be done before 
the Mass Termination Connector or ribbon connector is applied.  Average 
radio may take a couple of days on the bench to seek out the enhancements. 
Once all this is done, you will find the receive on the Omni VI Plus to be 
superior on the bands with few if any birdies found or heard.

The PA stabilization is basically accomplished by replacing the disk ceramic 
caps with chip type components.  Specifically, C4, C5, C6, C7, C10, C11, 
C12, C13, C15, C16, C17.  Also make sure that D2 and D3 are thermally 
connected to the heat sink.  This effort was done in as much as I run the PA 
at 10 to 15 watts, through a resistive attenuator to drive the VHF or UHF 
transverters.  At that level, there was some "nasty" stuff coming out of the 
PA and thus not normally found at rated output.  At rated output, the PA is 
normally very clean.

It is just so annoying to do weak signal work where one listens and listens 
and only discover it is a darn internal birdie about the noise floor level. 
Just the nature of crystal mixing radios.  They all have them, some worse 
than others, no brands/models exempted.

For what it's worth, the Omni VII, the Eagle and the Argonaut VI do not show 
any of these issues.  Makes for HAPPY HAPPY on the VHF and UHF bands.

73
Bob, K4TAX








----- Original Message ----- 
From: "Barry N1EU" <barry.n1eu at gmail.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Thursday, January 10, 2013 11:39 AM
Subject: Re: [TenTec] Fair Market Price for Omni VI+ will all 
filters&matching PS ?


> On Thu, Jan 10, 2013 at 4:00 AM, Bob McGraw - K4TAX 
> <RMcGraw at blomand.net>wrote:
>
>
>> I had done extensive work to get rid of the multiple birdies on 12M and
>> 10M. I replaced the bypass caps on the PA board to improve the stability 
>> of
>> the stage.  Although the changes were strictly component changes, 
>> selected
>> to be better quality or better suited for the application, and the added
>> toroids to certain cables inside the box were applied to get rid of
>> birdies.
>
>
> Sounds like you certainly added some value to your Omni 6+, Bob.  Any
> chance you documented those changes?  Many of us would be very interested!
>
> Thanks & 73,
> Barry N1EU
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>