[TenTec] Corsair II PBT Question

Barry N1EU barry.n1eu at gmail.com
Tue Oct 30 05:49:24 EDT 2012


The 756/757 will give you a symmetrical, but narrower, passband.  It
doesn't really make sense to go with one 2.8khz and one 2.4khz filter.
 Go with two filters of the same bandwidth.

I'd definitely go for the 2.8khz filters.

Barry N1EU

On Tue, Oct 30, 2012 at 9:36 AM, Daniel Schlieper
<daniel.schlieper at tuxomania.net> wrote:
> Hi Dave,
> I try to find the Inrad 2.8 kHz filter for 6 MHz IF, but cannot see anything
> suitable on the Inrad website. Do you know the order number?
> I wonder if this mod actually needs an 2.8 kHz filter. Would the 2.4 kHz
> filter (Inrad # 756) do as well? Or is the width critical?
> 73 Daniel DM3DA
> On Sat, 27 Oct 2012, David and Dianne on Comcast wrote:
>> Your PBT imbalance problem is likely caused by asymmetrical 2.4 KHz
>> filters in the Corsair II. This is a long known problem with the CSII, Omni
>> V and Omni VI's.
>> I have had similar experiences with all of the many (!) Corsair II's I
>> have owed over the years along with an Omni V and Omni VI. L/O and IF stage
>> alignments will not improve this problem caused the inconsistent performance
>> and design of the stock TT 2.4 KHz filters.
>> The remedy is to replace both 2.4 KHz stock filters with INRAD 2.8 KHz
>> filters in the 9 and 6 MHz IF stages and to make sure the the local ocs's
>> are adjusted as`perfectly as possible.
>> You will be rewarded with far improved SSB audio fidelity and wonderful
>> SSB TX audio.
>> What you are describing I experienced with all the TT radios of this IF
>> design that I have owned over the years. The 100% fix is this filter swap.
>> Pricey but really worth it. Any easy swap out.  You can also install the 2.4
>> KHz filter board (9 MHz) with sockets to make future filter swapping really
>> easy.  I think that Barry N1EU documented that mod. (Check out his really
>> neat CSII wiki site at http://corsair.wikidot.com/corsair-9mhz)
>> I have a last production run Omni V and last production run CSII that I
>> have switched out these filters and the results are super.
>> 73 de N1LQ-Dave
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