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
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Piotr Tomczak Ham call: la9hfa
Nera ASA E-mail: pito@satcom.nera.no
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