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  #16  
Old 02-02-2011, 11:39 PM
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John Folsom John Folsom is offline
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John, thanks very much for the scan. However, when I open it on my computer, it is so low resolution that nothing is readable. Could you try sending it to me as an email attachment? Maybe that will work.... jfolsomjr@cfl.rr.com

Thanks again!
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  #17  
Old 03-25-2011, 10:05 PM
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Restoring Admiral T2301
 
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The amount of equipment in my workshop hit critical mass so I took some time to sort through it. I definitely have too many sweep generators so did a little comparison using an Admiral 20A1 chassis.

The contenders were:

Jackson TVG-2
Hickok 615
Eico 369
Wavetek 1002
Wavetek 1080

The 369 and Waveteks use post-marker injection while the others mix the marker in with the swept RF output. The Jackson and Hickok work OK, but the response curves are kind muddy looking and the markers are not very distinct.

The 369 works well, but mine is definitely out of calibration. Also, the sweep width is not as wide as it should be.

The Waveteks both work very well and have distinct markers. They have also built-in harmonic markers at 1, 10 and 50/100 Mhz. A jack is provided for an external marker.

Here's the setup I settled on. The Wavetek 1080 and a good old Heathkit IG-102 for the variable marker.
The 1002 works just as well and has a neat 'angle' marker feature, but is rather heavy and some of the jacks are inconveniently located in the back.





After following the alignment steps carefully, I was able to match the sevice manual pretty darn well
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Last edited by bandersen; 03-25-2011 at 10:29 PM.
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  #18  
Old 03-28-2011, 03:53 PM
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Restoring Admiral T2301
 
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Here's the picture post-alignment. A little centering and linearity tweaks and it'll be darn near perfect I think



I recorded a little video while doing the alignment and will put it up on YouTube soon.
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  #19  
Old 03-28-2011, 09:00 PM
ctc17 ctc17 is offline
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I have done several sets using the BK415, more 60s color stuff. I have had fairly good luck but I can never get my curves to look that good. I bet most of its is due to bad caps etc in the IF.

I have the entire RCA alignment setup, have never played with it.

Alignment seems to be one of those things you get better at with practice. Im still learning, need to do about 5 more sets then I should have it fairly good.
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  #20  
Old 03-29-2011, 02:34 PM
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bandersen bandersen is offline
Restoring Admiral T2301
 
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Location: Chicago, IL
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I think the biggest challenge is obtaining quality, calibrated equipment. This particular set uses a separate IF for sound/video and stagger tuned video IF. You don't actually use a sweep generator for the alignment procedure. Rather you need an accurate RF gen. with good output attenuation. Also quality, terminated test leads are a good idea.

The sweep gen and markers are just to check you work. If the overall pattern is off, you need to go back through the fixed frequency tuning steps. I did about 4 passes to get it right.

I didn't touch any caps in the video IF, but I did replace some exposed micas in the sound IF cans. The biggest surprise was the effect swapping the 6J6 osc/mixer tube had.
The original was a little weak so I popped in a NOS one that tested great. However, this is the best response curve I could get.


I was considering popping the tuner open to check for bad components when I tried swapping in another NOS 6J6. That did the trick
I later read in the service info that indeed an RF alignment may be necessary after replacing the 6J6!


I do have an RCA WR-514 which like the 415 uses crystal controlled markers for 44 MHZ IFs, but all my sets are too old to use it.
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  #21  
Old 03-30-2011, 09:01 PM
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marty59 marty59 is offline
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Quote:
Originally Posted by bandersen View Post
Here's the picture post-alignment. A little centering and linearity tweaks and it'll be darn near perfect I think



I recorded a little video while doing the alignment and will put it up on YouTube soon.
Darn near perfect? That detail is amazing!

Unfortunately, I was brought up in the school of "don't mess with those IF's!" and to think of alignment as taboo however we did attempt to align an early Sylvania 25" color in my high school electronics class. I remember it looked pretty much the same as before the alignment and we used that model B&K that was styled the same as the 1077B Analyst. That was back in the seventies....I'd love to go through that procedure again sometime!
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