[TenTec] OMNI D

[veast1]

Ken,
 If you are refering to the Y2 filter in the Omni VI+, i changed mine 
from the stock 2.4 khz to an Inrad 2.1 filter.  I also have optional 
filters in the chain as well as the Inrad SSB roofing filter.  The 
signal is extremely clean and i have received excellent unsolicited 
reports on the audio. I would say that experimenting and testing could 
be beneficial for some.

73 Paul (N6MYA)




Ken Brown wrote:

>Hi Cal,
>
>     There are two common way of generating a SSB signal. There is the 
>phasing method, and the more common filter method. In the filter method 
>a double sideband signal is generated by a balanced modulator, and the 
>unwanted sideband is rejected by a filter, leaving only one sideband. 
>Almost every SSB transceiver uses the filter method, and shares the 
>sideband selecting filter used in transmitting with the receive function 
>in the transceiver. In the Ten-Tec Omni VI radios this filter is 2.4 kHz 
>bandwidth 8 pole crystal filter with a center frequency of 9.0015 kHz. 
>The transmit signal for SSB and CW modes goes through this filter, and 
>in the case of SSB this filter's characteristic determines the opposite 
>sideband rejection, and along with the audio circuitry and your 
>microphone, it determines the bandwidth of your transmitted SSB signal. 
>This filter also determines the maximum bandwidth of your receiver, 
>because it is always in the receive signal path, regardless of other 
>optional filters in either the 9 MHz IF or the 6.3 MHz IF. (Please note 
>that in FM mode this filter in neither in the transmit or receive path) 
>Normally this "default" filter is never changed, and will always 
>determine your SSB transmit bandwidth. Optional filters in either the 9 
>MHz IF or the 6.3 MHz IF only affect receive function, as they are not 
>in the transmit signal path.
>     It is possible, but generally not advisable, to change the default 
>filter. There are two reasons I have heard of for doing this. One is to 
>produce "High Fidelity" SSB. There are a number of good reasons not to 
>do this. The most obvious is that it consumes more spectrum in our 
>crowded bands. Another reason not to use a wider filter in the transmit 
>signal path is that it can degrade the carrier rejection. The balanced 
>modulator is not perfect, so some carrier is generated and then 
>attenuated by the opposite sideband rejecting filter.
>     A second reason for changing the default filter would almost only 
>be considered by people, such as myself, who don't operate SSB, or have 
>another radio to use for SSB. By putting a narrower filter in the 
>"default" filter position it is possible to improve the receiver 
>selectivity. Selection of the filter has to be done with care, so that 
>the bandpass coincides with the bandpass of any other optional filters 
>in the 9 MHz IF. The SSB transmit bandwidth would become narrower than 
>normal, making the SSB signal probably not pleasant to listen to. It 
>could possibly make for a good pile-up busting SSB signal, if the 
>filter, BFO frequency and operators voice were all matched just right.
>     All of the above applies to the Omni VI radios. There could be some 
>differences in the Omni D. I am not familiar with that radio. I am 
>certain however that as long as you do not change the stock "default" 
>transmit and receive 9 MHz IF filter, your transmitted signal will not 
>be changed.
>
>  
>