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[TenTec] Omni Noise

To: <tentec@contesting.com>
Subject: [TenTec] Omni Noise
From: pito@nera.no (Piotr Tomczak)
Date: Mon, 07 Feb 2000 15:54:10 +0100
Diffcult to answer for your question...
We are talking here about two different things.

The fix no. 1 helped most, if you consider the amount of
work I put into the project. The noise is practicaly gone...
But if you never work on higher bands
you never will be disturbed by that noise...

In case of fix no. 2 the most paid off, gives reduction of the RF gain knob
from max to 16:00 o'clock. Some people say they have to
reduce it to 15:30 to get rid of that noise. The soldering job give
very little pay off.

Best regards 
Piotr LA9HFA

At 08:17 AM 2/7/00 -0600, you wrote:
>Piotr;
>
>Thanks for the feedback and information.  I posted the original OMNI
>NOISE msg.
>
>Do you think any 1 or 2 specific changes made a big difference.  You've
>gone to a lot of work.  What changes produced the most result in noise
>reduction?
>
>Thanks in advance.
>
>73
>Bob K4TAX
>
>Piotr Tomczak wrote:
>> 
>> Hello to All noise interested people...
>> 
>> There has been some discusions about the noise and I discoverd that
>> I do heard two different types of noise on my OMNI VI+ 9 months
>> old model.
>> 
>> 1. The syntesier noise, mostly heard on a quiet night, specialy when you
>> tune around but it can also be heard on some frequencies as a currier.
>> 
>> 2. The Front/End noise of the RF/IF stage when the RF gain is on max.
>> Some body asked who runs with RF on MAX ??? I did on Drake
>> but I do not on TenTec.
>> 
>> Answers to problems...
>> 1.... I add additional screening to the controller board. Put physical
>> cover on the
>>         top of the board compartment.
>> I add ferrite bead on the DC +12V power lines into the control board.
>> I put most of the cables going out of the control board compartment though
>> the ferrite clips.
>> I add dcoupling capacitors of 10nF-20nf to most IC +/- legs
>> located on the controller board
>> 
>> It helped !!! The noise is so much reduced that I can bearly hear  it at
all.
>> Lots of effort but it is worht it.
>> 
>> 2.... There are some of the boards in TT which are double sided but the
>> laminate
>> do not have through plated holes. (pitty for a rig so expansive and
produced
>> at the end of 20th century but it is a fact...)
>> 
>> What I did I soldered caps and resistors to the grounding layer on
>> both sides of the laminate. Be careful not all components tolerate
>> overheating !!! Do it with causions. It is better to leave one cap
>> unsoldered on both sides then demage it.
>> 
>> Some boards are modified it that way directly from the factory!!!
>> 
>> It helped but not as much as I thought it will do.
>> So I run the rig with the rf gain at 16:00 and it is perfec.
>> The gain is still there and the noise is gone. I have more plans to
>> fix it permamently but right now I do not have neither idea or time
>> to do it.
>> 
>> For removing confusions . If you increas the RF gain from
>> 16 to 17 o'clock the signal is not increased only the noise.
>> 
>> Best regards It was my 1 krone to the discusion.
>> 
>> Maybe some fanatics did not liked it but maybe some
>> will try to improve the good rig any way to be better.
>> 
>> Good Luck
>> Piotr LA9HFA
>> 
>> --------------
>>    \\\@///
>>      ·    ·
>>        o
>> -------------
>> Piotr Tomczak           Ham call: la9hfa
>> Nera ASA                   E-mail:    pito@satcom.nera.no
>> 
>> --
>> FAQ on WWW:               http://www.contesting.com/tentecfaq.htm
>> Submissions:              tentec@contesting.com
>> Administrative requests:  tentec-REQUEST@contesting.com
>> Problems:                 owner-tentec@contesting.com
>> Search:                   http://www.contesting.com/km9p/search.htm
>
>
>
>
>
--------------
   \\\@///  
     ·    · 
       o      
-------------
Piotr Tomczak           Ham call: la9hfa
Nera ASA                   E-mail:    pito@satcom.nera.no


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