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RE: [TenTec] OMNI VI product detector IMD

To: "'tentec@contesting.com'" <tentec@contesting.com>
Subject: RE: [TenTec] OMNI VI product detector IMD
From: "Michael, Dana A" <dana.michael@tycoelectronics.com>
Reply-to: tentec@contesting.com
Date: Mon, 17 Jan 2005 11:04:20 -0500
List-post: <mailto:tentec@contesting.com>
Steve,
I have a schematic.

-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com]On Behalf Of Steve N4LQ
Sent: Monday, January 17, 2005 10:54 AM
To: tentec@contesting.com
Subject: Re: [TenTec] OMNI VI product detector IMD


Mike
I think I can locate the SL6440. Do you have the instructions for building 
the G4PKT prod det?

Steve N4LQ
----- Original Message ----- 
From: "Michael, Dana A" <dana.michael@tycoelectronics.com>
To: <tentec@contesting.com>
Sent: Monday, January 17, 2005 10:27 AM
Subject: RE: [TenTec] OMNI VI product detector IMD


> Clark,
>
> The Ten-Tec mod does help the in-passband intermod of the product 
> detector.
> I don't have a manual here at work, but as I recall you increase the lower
> capacitor of the divider capacitor pair after the IF amp buffer transistor
> just before the signal goes into the product detector. This reduces the IF
> level to the product detector and the intermod. The original capacitor is 
> a
> 1000pf and they have you increase it to 2200pf. Then to make up for the 
> loss
> of gain you change a resistor on the opamp section of the manual notch
> filter from 33K to 100K.
>
> I'm very sensitive to inband intermod and I think this type of 
> intermod -if
> very low- is what makes for a clean clear sounding receiver, more so than 
> a
> very high front end intermod number, because all signals in the passband
> generate phantom signals in the IF or product detector if they have a poor
> intermod spec. This in-passband rating is not given in most reviews but is
> very important to how clean a receiver sounds.
>
> I have done this mod. to my older OMNI-V and it makes the receiver sound
> much better.
>
> I have the G4PKT product detector in my OMNI-VI option 3 and it is even
> better. It is a much more involved mod. And the detector chip, an SL6440 
> is
> no longer available.
>
> 73,Mike W3TS
>
> -----Original Message-----
> From: tentec-bounces@contesting.com
> [mailto:tentec-bounces@contesting.com]On Behalf Of Clark Savage Turner
> Sent: Monday, January 17, 2005 12:43 AM
> To: tentec@contesting.com
> Subject: [TenTec] OMNI VI product detector IMD
>
>
> Hey all -
>
> Anyone with an early OMNI VI do the Ten Tec modification to improve the
> in-passband performance of the product detector?  I do not mean the 2nd
> order IMD mod that is done on the RF board (I have done this one and it
> does not help).
>
> If you have a fairly early OMNI VI, check with 2 stations in the
> passband with S9 or so, see if you can hear the beat note.  G4PKT
> produced a daughterboard product detector to cure the problem and Ten
> Tec did a fix for later OMNI's to take care of this problem.
>
> I spoke to Ten Tec and got some instructions to add two caps to the
> IF/AF board, I did what was suggested and got no improvement.  I'll
> call back to see if I have it correct, but just wonder if anyone has
> taken care of this and knows exactly what the remedy is.  I have the
> G4PKT board but would rather not install it if the Ten Tec remedy is
> sufficient.
>
> Clark
> WA3JPG
>
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