[TenTec] Omni-VI 2.8 KHz filters

[dnelsen at integraonline.com]

> The 9.0 Mhz filters are 200 Ohm inpedance In/Out.  Dave AB0N
>
>
> 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 at 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 at cox.net>
>> >Subject: [TenTec] Omni-VI 2.8 KHz filters
>> >To: tentec at 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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