[TenTec] Re: Pegasus Filtering

[WA3FIY]

Thanks for the tip Carl, good suggestion on how to measure the 
shape factor.  I'll give that a try when I get a chance.

In a connected vein, I used my Pegasus in the 160 meter 
contest this weekend and was pleasantly surprised at the 
selectivity.  It did a good job but I was especially surprised to 
discover the value of so many filter selections.  Using Carl's 
control software and the tuning pod, I was able to "fine tune" 
the filter/passband combination to get single signal selectivity.

I wound up with the selectivity set at 1050 hz and the 
passband tuning set to around +400 to +600 hz depending on 
the transmitting station.   Yes, signals sounded rather 
constricted but clear; AND the big advantage of this setup is 
that interfering signals were usually outside the bandpass, 
hence, they did not trigger the AGC.  If you have not tried it 
yet, give that combo a try.  It seems the key to making this 
work is "tuning" the passband tuning to bring maximum 
intelligibility from the transmitting station.  The best setting 
varied from station to station.

I first thought the 35 filters were a gimmick.........I'm now 
beginning to appreciate the added flexibility they bring to the 
table.

-Lee-

On 26 Feb 2002 at 12:44, Carl Moreschi wrote:

> Lee,
> 
> The 300 hertz filter in the pegasus does not have a 1.5 to 1 shape
> factor. If you tune in an S9+20 signal, you will find the filter is
> S9+14 or higher over a 300 hertz range.  This is 300 hertz at the 6 db
> points.  You will also find that the range for this signal being at
> least S2 (60 db points) is about 1200 hertz.
> 
> The rx340 specs also state the filters are all 1.5 to 1 or better
> shape factor.  The big difference here is they really are.  The same
> test above with the 100 hertz filter in the rx340 yields 100 hertz
> between the 6 db points and 120 hertz between the 60 db points for a
> real shape factor of 1.2 to 1.  There is no need to disable the AGC
> with this method.
> 
[snip]