[TenTec] OMNI-6+ cw offset adjustment

[Arthur Trampler]

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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