[TenTec] 546 Omni ''C''

[Steve Ellington]

Further clarified: It has no optional crystal filters. The 2.4khz filter
is used for both transmit and receive and is soldered in. There are two
extra filter slots open, 1.8khz and .5khz. The 150hz filter mentioned is
an audio filter which has 3 positions, providing bandwidths suitable for
cw. This audio filter is in the agc loop and does an amazing job but not
quite as well as having the optional filters. 

The reason I bring this point up is because I've run into a lot of
confusion and mistatements about what filters a rig actually has.
Recently, a Delta 580 was advertised as having "all factory filters". The
owner wasn't familiar with TenTec rigs and since all filter positions
seemed to work, he assumed it had them. I had him remove the top lid and
look. He still couldn't tell if the .5hz filter was in there. Anyway, I
bought it and of course, had to order a filter for $89. 

TenTec was big on audio filters. The Tritons, Argonaught's, power mites,
Century's amoung others, all used them for cw reception enhancement.
Later, with the Omni, Delta and Argosy's crystal cw filters were offered
as options to the already effective audio filters. These crystal filters
provide better strong signal rejection. Still later, the crystal filters
became predominant as in the Paragon and Omni V. In these, the audio
filter was taken out of the agc loop and lost it's reputation as an
effective filter. Now if you want selectivity, you must shell out the $$$
and buy the crystal filters. 

The Omni C had the ultimate combination of audio and cw filtering. A 3
position switch allowed selection of 3 crystal filter bandwidths and
another 3 position switch provided 3 positions of audio filter bandwidths.
All six were within the agc loop! My favorite setup for cw is the 1.8khz
crystal filter and position 2 of the af filter. Listening to cw with that
setup almost brings tears of joy. 

On Wed, 7 Apr 1999, Donald F. Smith wrote:

> 
>  Gentlemen,
>  the Omni has only stock filters.
>  it is a 2.4khz this one determines the i-f bandwidth.
>  in short its 150hz bandwidth centered at 750hz.
>  shape factor7.2 to 1 @6/60db. has three selectable response curves. hope
> this helps.
>  
>  Regards,
>       Donnie
>                     Reply to:n4jzh@amsat.org
>                                   or
>                              n4jzh@mindspring.com  
> 
> 
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> 

Steve Ellington N4LQ
N4LQ@IGLOU.COM


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