[Hammarlund] HQ-110 alignment

[Kenneth G. Gordon]

On 6 Apr 2006 at 9:46, Julian Bunn wrote:

> Several people asked me about the setup I'm using. I've put some
> details at the following link:
> 
> http://pcbunn.cacr.caltech.edu/jjb/hammarlund/if_alignment.htm

That is a very good setup you have there, Julian. Well done.

> I'm actually using a 1ms sweep rate ...

In the scope. Yes. That would be correct for the way you're doing it.

> and would be interested
> to hear what the disadvantage of a fast rate like this is.

None, in the way you have yours set up.

What I meant was the sweep rate of the sweep generator, which on 
your website you say you have set to a very low value, 10 
seconds/sweep, you say. THAT is what I meant.

However, the difference between the way you do it and the way I 
do it, is that I connect the sawtooth-output of the sweep generator 
to the scope's external sweep input, so that it controls the scope's 
horizontal sweep rate. I.e., at the instant that the sweep-generator 
starts to sweep from 400 Khz, the trace starts on the left side of the 
scope screen, and when the SG reaches 500 Khz, the scope trace 
is just reaching the right side of its screen. They are synchronized.

Your scope trace shows a double trace, above and below the 
center line, which is fully acceptable and shows you exactly what 
you need to see, if interpreted properly.

My method shows a single, exact representation, of the IF 
passband, one hump above the scope center line, and none below 
it.

The differences in our methods are simply a matter of preference, 
although in my method, since the horizontal sweep rate of the 
scope is controlled by the sweep generator, and is so slow, the 
trace is VERY hard to see in strong light. That is why I said that I 
had to have the room darkened, or a scope with a long persistence 
trace should be used.

Again, my heartiest congratulations and thanks for posting your 
method. Many people have asked me how I use that method, and I 
have not had the time to post it to a web site.

You have preformed a valuable service for our community.

Ken Gordon W7EKB