Don - When I was discussing the passband of the two filters, what I was
really getting at was the passband ripple of the two filters. I don't
think that they have very good shaping compared to the INRAD filters.
If the passband ripple is different between the two filters, then you
can have significant loss even if they are set correctly with the
passband tuning. The center frequencies aren't critical due to the
conversion scheme. In my radio, the TT filter pair was quite lossy.
Even with the gain set on high the 250Hz filters were significantly down
on signal level. I had to add an amplifier stage following the N-2
filter to get the gain to balance between the 500 and 250 filters.
When I installed the INRAD filters I removed the added amplifier and
gain balance was identical between the 250, 500 and SSB filters.
On 1/25/2011 3:17 PM, Don Jones wrote:
> 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?
> Don Jones KO7i
> Arlington, WA
> -----Original Message-----
> From: John Oglesby [mailto:firstname.lastname@example.org]
> Sent: Monday, January 24, 2011 6:28 PM
> To: email@example.com
> Subject: Re: [TenTec] Omni VI 1st IF Narrow CW Filter Enable?
> The gain balance is good with the roofing filter and cascaded INRAD
> 250Hz filters. Before this set-up I had some issues with the TT 250Hz
> filters installed. The passbands didn't work well together and I had to
> add some additional gain.
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