Re: [TenTec] INRAD Omni VI roofing filter kit - success

[Clark Savage Turner <csturner@kcbx.net>]

On Jan 14, 2005, at 10:38 AM, Ken Brown wrote:

> Hi Rick,
>
> Yes I understand where that Inrad mod puts the new roofing filter. I 
> guess what I did not understand is that with only one NAR button on 
> the Omni VI (non version 3 or Plus) you sort of have to leave out the 
> "regular" narrow 9 MHz optional filter. ... Now I

I think you still misunderstand (or else I do :-)

The roofing filter mod switches in/out at a point before ANY of the 
optional filters in the OMNI VI (the NAR in the 9 MHz position or the 
others in the 6.3 MHz position).  It is where Ten Tec has a small 15 
kHz wide filter already, and the roofing filter puts another filter in 
line (or out of line) where that 15 kHz wide filter already sits in the 
line.  So the filter that gets switched out of the line is this little 
15 kHz wide filter in the line BEFORE any of the filters we normally 
think about.  It is NOT any of the 8 pole crystal filters, stock or 
optional.

So, ALL the Ten Tec optional filters may be utilized.  You lose nothing 
at all.  You do not lose any mode that requires wider bandwidth either, 
because the roofing filter takes itself out of line for FM (and you can 
do it with the NAR switch anyway, depending on your choices).

The only thing you might have wanted is a separate switch to put the 
roofing filter in/out even when you have the NAR filter pressed.  
Normally, the NAR switch (or ONE of the NAR1 and NAR2 switches in the 
OMNI VI plus and option 3 versions) puts the roofing filter in line.  
You could, conceivably, use another switch somewhere else, and put the 
stock 15 kHz roofing filter in line (roofing filter mod out of circuit) 
when you wanted to without reference to any other switch.

Now, even if you have NO filter in the NAR position, you still will use 
that button to switch the roofing filter in/out of the circuit.  You 
don't need a filter in there (but, of course, it adds to selectivity!)

Clear as mud?  If I misunderstand your words and appear condescending, 
I apologize in advance.  Wish I could diagram this, it would be much 
simpler.

Clark
WA3JPG


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