[R-390] IF sweep alignment

[Curt Nixon]

Yep.  You need a sawtooth to feed the horiz plates via external...the 
sine input makes the display non-linear in X.

Another way might be to get a sync pulse out of the generator and use it 
to trigger the sweep of the scope.

You just need to make sure that what is sweeping the generator and the 
scope need to be same-same.

(technical term)

Curt


KA9EGW wrote:
> Trying to do IF sweep alignment so I can look at the bandpass visually.  I
> haven't done this since '79, and then the receiver under test was an
> HQ-1w29X, with a then-30-year-old 500kc heathkit scope and a 1950's Eico
> sweep generator.  Now I'm trying to do it with a HP8640B sig/gen and a 20MHz
> dual-trace Hitachi.
>
> So I feed the FM-modulated RF into the antenna input of the 390A, feed the
> scope's vertical plates from the IF output on the rear of the 390, and feed
> the scope's horizontal plates from the 400Hz sinewave output of the 8640B.
> Can't get her to sync up with the scope in x-y mode.
>
> Before I consume too much more bandwidth, is the fact I'm feeding the
> horizontal plates with the 400cps modulating freq the problem?  Seems to me
> last time I did this that old Heath scope had a sawtooth output on the back
> with which I fed the external sweep input on the sweep gen, which sawtooth
> output the Hitachi scope doesn't have. :-(
>
> I'm thinking I ought to see if I can borrow a function generator from work
> that does sawtooth and feed both the external modulation input of the
> generator and the scope's horizontal plates with that.
>
> [Of course I'm also thinking this would be a good excuse to buy a better
> scope, but alas, having just acquired that 8640B I dunno if I could get a
> new scope past the "Appropriations Committee" HI HI].
>
> Am I on the right track here?  I mean as far as my test setup goes.
>
> 73, Brian KA9EGW
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
> On Behalf Of Curt Nixon
> Sent: Saturday, February 26, 2011 10:26 AM
> To: r-390 at mailman.qth.net
> Subject: [R-390] My New R-390A Rework Project Blog
>
> GM:
>
> For any interested, here is a link to my blog on re-working my first R-390A
> Please feel free to comment there or here--I'm a newbie w/the R-390A so
> having a ball scoping out all the istory and information available on-line.
>
> http://curtsworkshop.blogspot.com/
>
> Curt
> KU8l
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