[GreenKeys] scope

[Eugene Hertz]

ok - so here's the fundemental question.

I am using the scope to tune the radio. There are two approaches I can see taking, which one is right?

1. Using my function generator, pump 2125 and 2295 into the TU and using a grease pencil, mark two lines on the scope that go though the major axis of each ellipse. Then, when I tine the radio, I tune so that the ellipses are lined up with the pencil marks. This would ensure that I have tuned the radio such that the mark and space frequencies are 2125 and 2295.

2. using the function generator, find whatever frequency makes the st6 meter point to the max number (in tuning mode) then mark the scope?

Having written this email, it seems #2 is the right approach.  

So it sounds like I shouldn't care about the orientation of the ellispes as long as I can reproduce it.

Thanks everyone!
Eugene


>-----Original Message-----
>From: Jack [mailto:wa2hwj at att.net]
>Sent: Sunday, March 18, 2007 08:50 AM
>To: 'greenkeys'
>Subject: RE: [GreenKeys] scope
>
>ZCZC 
> 
>The Fleshers and later HAL's use active filters which always gave 
>a nice sharp scope pattern (usually a straight line). The toroid 
>filters are inherently wider, thus the thin elipse, and also 
>subject to 
>ringing, phase shift, low Q, etc. Circuit parameters also affect 
>the 
>interaction between the filters, thus adding more to the 
>distortion in the scope pattern. Whenusing multi-section toroidal 
>filters, as discussed in the original TT/L articles, the 
>filtering/performance is better, obviously, and the scope pattern 
>is 
>much more of a line or very thin but straight elipse. 
>You shoud see the patterns from the horizontal oscillator 
>tunable coils used in the very first TU's, like the Twin 
>City TU and the W2PAT and W2JAV models; looked like 
>two footballs! But they worked... 
>My first TU, a Twin City Tu, had one filter and it was a 
>tuned audio output transformer secondary...I was 13 at the 
>time, what did I know? But, it worked, too. After mowing 
>a few lawns, I was able to afford two toroids, which Byron, W2JTP, 
>personally tuned for me! 
> 
>73, 
>Jack WA2HWJ 
> 
>NNNN 
> 
> 
> 
> 
> 
> 
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