[TenTec] OMNI-6+ cw offset adjustment

[Bob Henderson]

Arthur

Just a couple more bits of info which might be helpful.....

The Ten Tec optional 9MHz CW filters are centred on 750Hz not 800Hz as I 
previously stated.

According to the website, which I have just accessed at:

< http://www.qth.com/inrad/tentec_menu.htm >

Inrad offer three optional 4-pole roofing filters:

#764 is a 2400Hz b/w SSB filter
#763 is a CW roofer for standard tone (centred on 750Hz)
#765 is a CW roofer for low tones (500 - 600Hz)

Two alternative 400Hz CW filters are offered for use at the plug-in 9Mhz 
location:

#753 is centred on 600Hz
#759 is centred on 700Hz

Only one 250Hz filter is offered:

#760 which is centred on 700Hz.

Bob, 5B4AGN


----- Original Message ----- 
From: "Arthur Trampler" <atrampler at mchsi.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Monday, July 02, 2007 2:08 AM
Subject: Re: [TenTec] OMNI-6+ cw offset adjustment


> Thank you all for the input.  It appears the Inrad filter probably centers
> around 600hz, given its center frequency.  I will follow up with them.
>
> For the right price, this is what I'll get, I'm sure (my brother has one 
> he
> doesn't much care for, and is holding it while I save my pennie).
>
> 73
>
> ----- Original Message ----- 
> From: "Clark Savage Turner" <csturner at kcbx.net>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Sunday, July 01, 2007 11:19 AM
> Subject: Re: [TenTec] OMNI-6+ cw offset adjustment
>
>
>> On Jul 1, 2007, at 8:18 AM, Bob Henderson wrote:
>>
>>> CW offset is indeed adjustable from the front panel and I believe
>>> sidetone
>>> pitch tracks CW offset.  What is not adjustable is filter centering,
>>> which
>>> is fixed at 800Hz.  If you're happy listening to a tone between
>>> 600-1000Hz
>>> this works fine with cascaded filters as narrow as 500Hz.  However, if
>>> your
>>> preferred receive tone is 450Hz this doesn't work nearly so well.  The
>>> problem is significantly exagerated if 250Hz filters are used.  Years
>>> ago, a
>>> bunch of folks had filters made with lower centre frequency, so as to
>>> deal
>>> with this problem.  I'm not sure but I suspect Inrad made the filters
>>> and I
>>> believe they were centred somewhere around 600Hz.
>>
>> Bob has this right.  You can go ahead and set the CW tone offset and if
>> you want to use a narrow CW filter in the NAR position (the 9 MHz IF)
>> you are stuck in the passband (fixed) of the 9 MHz CW filter.  If you
>> like to hear CW at the lower notes (below 500 Hz, like I do), you'll
>> suffer loss at the edge of the filter response.  Of course, you can use
>> your PBT control to work with the 6.3 MHz CW filters, no problem there,
>> but the NAR filters in the 9 MHz position have fixed center frequency
>> and you can't move that (well you can realign the radio...)
>>
>> Yes, Ten Tec asked Network Sciences to make them a filter to deal with
>> this, I was probably the original guy to ask for, and to receive, a
>> model 221 CW filter.  This is the 250 Hz CW filter for the 9 MHz IF
>> with a 500 Hz center frequency, beats heck out of the model 219 for
>> listening at the lower tones, allows me to hear "down into the noise"
>> quite well.  The  model 219 filter is 250 Hz wide with the 750 Hz
>> center frequency, if you try to listen down at 500 Hz you suffer awful
>> loss (and with my 221, if you wanted to listen up at 750 Hz you'd
>> suffer the same sort of loss).
>>
>> Clark
>> WA3JPG
>>
>> Clark Savage Turner, J.D., Ph.D.
>> Professor of Computer Science
>> Cal Poly State University
>> San Luis Obispo, CA. 93407
>>
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>
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