[Chas]

The fix is oh so familiar to me...

Chas

[radiorich]

Hello Tony,
Sounds like a good plan glad you got your issues resolved .

Sincerely Richard

[dconant]

I want to thank all of you for your support in getting this radio back to playing correctly. I probably should examined the oscillator coil earlier but I just had it in my head it was and antenna circuit problem. I learned from this.

Question for you guys. Can you do an IF alignment by monitoring the AVC voltage?

[radiorich]

Hello dconant,
To asnwer your question, Yes you can do IF alignment by monitoring the AVC voltage.

Sincerely Richard

[morzh]

My answer is a bit different.

Yes you can. But it won't be as accurate.
The reason is, it is ALWAYS better to watch the signal change itself rather than a signal that is a reaction to the signal's change.

[RodB]

I always use the AVC to set up the IF. For me, monitoring the signal at the audio output is too variable and I end up setting an average. The AVC does that for me. Plus, I have a good idea how the AVC is reacting and doing it's thing. If you evaluate FM tuning meter circuits and the tuning eye circuits in some radios you'll find the AVC voltage is the source.

[Chas]

morzh

My answer is a bit different.

Yes you can. But it won't be as accurate.
The reason is, it is ALWAYS better to watch the signal change itself rather than a signal that is a reaction to the signal's change.

---

I agree, It is the Miller effect of grid voltage that shifts the reactance of the grid circuit creating a false peak to the adjustment. I have never encountered alignment instructions that specify using the AVC. The procedure surely exits, but disabling the AVC or using such a low signal input the AVC does not change insures that peak is achieved. It also reveals any issue with a an adjustment such as broad response or no response (circuit issues). In some receivers there are more than one timing circuit involved too as well as a boosted AVC taking an initial voltage for a power source.

So common was the use of the audio output for alignment many VOM's included an "Output" function.

YMMV

Chas

[dconant]

Mike, Got my new scope this morning. Here is the waveform. Hopefully it shows what you want. I had no idea this scope would have so much I don't understand.

   

[Chas]

Looks fine to me, but I'm not Mike...

I "had" a TDS-460. Did everything I wanted and its results earned me a substantial raise solving a spurious strobe triggering issue.

Before I retired, I had to train a replacement. The TDS stymied him. So, he used the auto-setting feature, results confused him more.

Overall, I found triggering from another channel at setting and filters very desirable to catch one time event issues.

I id not have to use the full potential in my work but found the print feature very useful in showing management of issues and their resolution.

The set-up memory was also very useful until my trainee decided "he" didn't need it, my setups were deleted (:

Chas

[morzh]

Chas

Our tastes in waveform seems to be similar, despite you not being me
Looks just fine.


Dconant

This is what I wanted to see. The waveform, as you can see, is symmetrical. Not the ideal sinewave, but good enough and symmetrical; however if you look at the old pictures, you could see how the lower half narrows towards the bottom, kinda like a long "V". This is what your old scope does to the waveform.
This is why I asked you to take it with the new scope, as this one should give you some faithful representation.

As for "so much I don't understand", for the radio troubleshooting most is not even necessary, but if you have an inquisitive mind, take the manual and play with it a bit, or watch a video(s) which, I think, should exist.

The scope is digital, so the triggering is obviously more powerful than simple level setting in old analog scopes. You could set rising/falling edges, delays, filtering, possibly some logic conditions on which to trigger; you could do some digital measurements, you could possibly do some Fourie analysis and math...Save and recall waveforms and many other things.

The manual is your friend.

https://cdn-aorpci9.actonsoftware.com/ac...ide_EN.pdf

The Pattern Triggering is very cool.

PS. Do the probe compensation routine, that is important.

[dconant]

Thanks Mike, Been looking at the manual. Quite there to digest.