Re: [TenTec] Omni-VI 2.8 KHz filters

[Charles Greene <cgreene@cox.net>]

Tnx Chuck,

I found it.  It's on page 4-45 of my manual; I guess there are a lot of 
variations of the manual.

Concerning placing the 2.4 KHz 9 MHz filter in the 1.8 KHz filter position 
and so on after installing the 2.8 KHz filters that I discussed below, a 
more careful look a the schematic revealed different input resistors for 
the various filters.  The appear to be attenuators, probably for 50 ohm 
filter inputs to compensate for different losses in the different 
filters.  They shown on the Pass Band Tuning Schematic.  Rather than modify 
the board and replace the resistors, I will just swap the filters and see 
how it sounds.  Then I will run a test using Spectrogram with a white noise 
source for the receiver and see what the band pass and level are when using 
each filter.

Tnx agn,

Chas, W1CG

At 08:21 PM 1/28/2005, c-hawley@uiuc.edu wrote:
> The carrier null is on the TX audio board...that would be
> page 4-39 in the Omni VI book or 4-25 in the Omni VI+ book.
> The pots to adjust are R3 and R4 at the input of the opamp
> U4...the balanced modulator. The page 4-37 right hand column
> bottom of the first full paragraph mentions carrier
> null...this would be page 4-23 in the "Plus" manual.
> Chuck, KE9UW
>
>
> ---- Original message ----
> >Date: Thu, 27 Jan 2005 20:28:55 -0500
> >From: Charles Greene <cgreene@cox.net>
> >Subject: [TenTec] Omni-VI 2.8 KHz filters
> >To: tentec@contesting.com
> >
> >Hi
> >
> >I got the two 2.8 KHz filters for my OMNI-VI yesterday and
> reviewing the
> >documentation, I can't find that it says to null the
> carrier again.  I
> >looked through the manual and I don't see anywhere you can
> null the
> >carrier.  Did I miss it?  Does the carrier null just apply
> to the
> >OMNI-V?  I don't mind doing it, but I just can't find where
> it tells you
> >how to do it.  The only thing I found in the manual is
> setting the
> >frequency for the PBT control, which might be a good idea
> to do.  I have an
> >OMNI-VI purchased in 1994 with the + mod done by Ten-Tec.
> >
> >I also ordered the 600 Hz roofing filter, but they said it
> wouldn't be
> >shipped until March.  Inrad did give me a 5% discount for
> buying 3 filters :-)
> >
> >I am planning install the Inrad 2.8 KHz 6.3 MHz filter in
> place of the 2.4
> >KHz "standard" filter, move the 2.4 KHz filter to the 1.8
> KHz filter
> >position, move the 1.8 KHz filter to the .5 KHz position,
> leave the .25 KHz
> >filter in place and relabel the filter switches.  When
> done, I will have
> >three different 6.3 KHz SSB filters: 2.8, 2.4 and 1.8 KHz.
> I don't see
> >anything on the schematic that would keep this arrangement
> from
> >working.  With the 600 Hz roofing filter, I plan to have it
> activated by
> >either the NR1 or the NR2 switch.  I have a 500 Hz 9 MHz
> filter in NR1 and
> >a 250 Hz filter in NR2.  All filters are OEM except the 2.8
> KHz filters and
> >the roofing filter.  Comments on this arrangement?
> >
> >73,  Chas,  W1CG
> >

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