[TenTec] 500 HZ Roofing Filter Attenuation-Orion

[Toby Pennington]

Pete,  I agree, there seems to be little or no drop except for very weak
signals, signals that don' t move the meter.  I worked for three hours
tonight recentering both filters and think they are set OK. As I said, you
will not notice it unless you compare copying a very weak signal with and
without the filter engaged.  Have a Good Nite!   Toby W4CAK

----- Original Message ----- 
From: <ac5e at comcast.net>
To: <tentec at contesting.com>
Sent: Wednesday, August 04, 2004 2:55 PM
Subject: Re: [TenTec] 500 HZ Roofing Filter Attenuation-Orion


> Hi, Toby: listening to a QSO on 14.024.86 just now and there's very little
drop down when the 500 Hz filter kicks in.  Or the 250, for that matter. But
I have a question for you.
> Have you set and optimized the C.F. (center frequency) adjustment? The
drill is to tune in a middlin' strong CW signal, dial down the bandwidth
until the 500 or 250 Hz filters kick in and then set the filter offset for
max signal.  While I suspect every filters center frequency is a bit off the
nominal frequency,  my 500 Hz filter is set to -160 and the 250 is set
for -220 Hz.
> I found  a steady S5 signal, turned the BW down to 100 Hz, then set the
250 Hz filter offset. Start by noting the frequency where the signal starts
getting louder,  over shoot the CF adjustment by 200 Hz or so, then dial
back down to where it just starts getting louder again. Split the difference
and your filters should be centered in the passband. Then I repeated the
drill at about 300 Hz for the 500 Hz filter.
> For just the 500 Hz filter dial down to maybe 250 and then go through the
CF adjustment. It makes a lot of difference for me.
> 73  Pete Allen  AC5E
>
>   r
>
>
>
>
> --
> Never squat with your spurs on
>
>
> -------------- Original message -------------- 
>
> > I have noticed that on 20 mtrs with all the roofing filters turned on to
AUTO,
> > that there is considerable attenuation of receiver audio when the
bandiwdth hits
> > the 370 HZ level. Of course I am down in the cw portion of the band. It
doesn't
> > seem to bother loud signals but does indeed surpress weak signal
reception when
> > the bandwidth is anywhere between 370 HZ down to 200HZ. At 190 Hz the
audio
> > comes back up because then the 250 HZ filter kicks in. I can turn the
500 HZ
> > filter off and the audio is normal strength level. Does anyone else
notice this
> > or does this sound like a bad 500HZ roofing filter? One other thing, I
don't
> > seem to notice it on the low bands, but 20 mtrs and above it is most
noticeable.
> > I noticed in the QST review of the Orion the reviewer noted a somewhat
similar
> > observation with the 500 HZ filter. Toby W4CAK
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