[Hammarlund] Re: Sweep Method for Alignment - doing it at RF.

[Kenneth G. Gordon]

(Forwarded from the Glowbugs list)

"Ron D'Eau Claire" <rondec at easystreet.com> wrote:

I used to do that on land mobile gear using a Cushman or IFR Service
Monitor in FM mode to make it 'sweep' a frequency range greater than
the I.F. bandwidth of the receiver. 

Works FB.

The receiver 'front end' selectivity is in the loop, of course, so I
guess you'd not want to be using some sort of extreme selectivity
gadgets there such as a Q-multiplier, but it's pretty extreme to think
that any front end selectivity could approach the I.F. selectivity
close enough to be a concern...

Ron AC7AC

>Sparkwireless at aol.com wrote:
>
> Ken,
> 
> My sweep generator won't go below 15 mHz. Can I tune the receiver to
> that frequency to sweep the IFs?
>
> I think so, but have never done it. 
>
> In fact, I was thinking about that last night. 
>
> It seems to me that you could definitely do that, as long as you could
> properly sychronize the scope's horizontal trace to the signal
> generator.
>
> Your SG should be able to output a sawtooth sync wave form. As I
> mentioned before, if your SG outputs a triangle wave, you will get a
> double, side-by-side and reversed, trace on your scope.
>
> If you could connect a diode detector at the input of the 1st mixer,
> you could then use this method to align your RF amp stage too.
> 
> As one of our subscribers mentioned to me, what we have here in this
> "visual method" is a sort of poor-mans spectrum analyzer, but at 
> much reduced bandwidth.
> 
> Ken W7EKB