[R-390] sweep alignment

[Tom-WB3AKD]

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
>
>
>
>
>