[R-390] Visual Alignment

[Bob Camp]

Hi

You can also do this with a modern network analyzer. I suspect Dave 
Medley was the first to take a shot at it on a 390 and report the 
results here on the reflector. Several others here have tried it as 
well.

The main problem is that the delay time / ringing through the 
mechanical filters is pretty long. If you think about it they are audio 
gizmos and you have to wait for the sound to go from one end of them to 
the other. That doesn't sound like much but it can easily get up to a 
fraction of a milisecond. In some filters it can run tens of 
miliseconds. What happens on your sweeper is that the display shifts so 
center frequency is no longer at center screen.

There is always a temptation to speed up the sweep so you can see 
what's going on faster. When you do so the results you see are not as 
accurate as they should be.

An interesting replacement for the sweeper is a rig using a computer 
sound card in various configurations to generate and detect the signal. 
The main claimed advantage is that you can use the computer to store 
the results and don't have to try to figure out a couple of hertz rep 
rate on a P7 phosphor screen.

	Take Care!

		Bob Camp
		KB8TQ

On Jun 5, 2004, at 9:23 AM, Commtekman at aol.com wrote:

> That is probably the procedure from the Army Security Agency in Fort 
> Deven's
> Mass, of which I attended 44 years ago-
> Bob K6OSM
> Mccall, Idaho
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