[R-390] sweep alignment

[Bob Camp]

Hi,

When I went through this I just did it the easy way and hit it with a
network analyzer. I forget the model but it's the one that goes to 11 MHz
and then you switch the cables to get it to go to 22 MHz. If I remember
correctly Dave Medley did it the same way. Later on I tried it with a 200
MHz network analyzer and ran into the same set of issues.

    Take Care!

        Bob Camp
        KB8TQ


----- Original Message -----
From: "Tom-WB3AKD" <wb3akd@arrl.net>
To: "Bob Camp" <ham@cq.nu>; "Steve Hobensack" <stevehobensack@hotmail.com>;
<r-390@mailman.qth.net>
Sent: Sunday, January 12, 2003 11:22 AM
Subject: Re: [R-390] sweep alignment


> Bob,
>
> What are you observing the output with?
>
> 73
>
> Tom
> ----- Original Message -----
> From: "Bob Camp" <ham@cq.nu>
> To: "Tom-WB3AKD" <wb3akd@arrl.net>; "Steve Hobensack"
> <stevehobensack@hotmail.com>; <r-390@mailman.qth.net>
> Sent: Sunday, January 12, 2003 11:14 AM
> Subject: Re: [R-390] sweep alignment
>
>
> > Hi,
> >
> > Here's the basic problem with sweep alignment on the R-390 - you have to
> go
> > *slow*.
> >
> > A number of people have given this a try and most of us oddly enough
have
> > used the 3336 or one of it's cousins.
> >
> > In this case passband ripple = narrow peaks in the filter = narrow band
> > stuff in the filter = long time delay in the filter.
> >
> > It's the same reason you don't normally see mechanical filters in the IF
> of
> > a FM radio.
> >
> > The only way to be sure you are going slow enough is to keep slowing
> things
> > down until the result doesn't change. Start with a sweep of just the
> > passband. Don't worry about the entire filter response. Try something
like
> > 30 seconds for the 2 KHz filter and see what you get. Back it off to two
> > minutes to be sure that the result is correct. From there you can speed
it
> > up to the point is begins to look weird.
> >
> > Since you can't do anything about the response of the mechanical filters
> > some of this may not be needed. The only thing you can do anything about
> is
> > the tuned coils in the IF strip. You may be able to set them adequately
> with
> > a sweep speed that does not properly display the response of the IF.
> >
> >     Take Care!
> >
> >         Bob Camp
> >         KB8TQ
> >
> >
> >
> >
> >
>
>
>
>