Lining up the two filter passbands is a front panel control. Called PBT,
paragraph 3.5-12 in the manual. Its anticipates that the first filter
would always be SSB bandwidth, so the bandpass tuning with a CW filter
would move it across the SSB pass band. With the narrow first IF filter
there isn't much pass band to move across. So the effect is mostly
further narrowing of the CW pass band if the PBT setting doesn't set the
second IF filter within the pass band of the first IF filter.
As you tune PBT to lower the CW pass band frequency, you soon have the
lower limit set by the first filter and the variable upper set by the
second filter, and you tune another 200 Hz or so and they no longer
overlap and then it takes lots more gain to hear any signals. And when
you tune BPT up in frequency, the first filter sets the top side of the
receiver pass band while the second filter sets the low side and again
you can tune to no over lap and no signals. In a compromise you can tune
for a very narrow pass band but the first filter sets one side of that
filter frequency.
I found with my Corsair II that I could use the two SSB filters to
achieve a quite usable narrow CW response without having to use a CW
filter just using the PBT knob. I didn't get to select the frequency
though and there the CW filter that I eventually installed makess it
handier.
73, Jerry, K0CQ
On 1/25/2011 2:17 PM, Don Jones wrote:
> John,
>
> I think this is the problem I am having with my 6 (opt 3). I have TT 250Hz
> Filter in the 2nd IF and it's center freq does not line up with the 1st IF
> new INRAD 400Hz CW Filter. In addition I need some more gain. I presume you
> simply changed a couple resistor value's for the narrow post filter amp.
> What you settle on for your radio?
> 73,
> Don Jones KO7i
> Arlington, WA
>
>
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