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  #31  
Old 08-31-2012, 11:53 PM
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Thanks. Yes, they are all 105C rated caps
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  #32  
Old 09-06-2012, 09:29 PM
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The replacements tube sockets from Surplus Sales of Nebraska have arrived and are identical to the originals
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  #33  
Old 09-06-2012, 09:37 PM
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Quote:
Originally Posted by bandersen View Post
The replacements tube sockets from Surplus Sales of Nebraska have arrived and are identical to the originals
Cool, are you replacing them all?
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  #34  
Old 09-06-2012, 09:39 PM
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Oh no. Just the 7-pin socket that broke in the upper left obscured by my hand. I have four more Predicta sets to restore though and they have some damaged sockets too so I stocked up.
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  #35  
Old 09-07-2012, 05:05 AM
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How long has the restoration took?
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Last edited by radiotron; 09-12-2012 at 07:57 PM.
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  #36  
Old 09-09-2012, 02:33 PM
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The first post is dated Aug. 19th so it's been about 3 weeks so far.

I popped out the K6 network to do a little testing. It's tough to do because of the internal parallel and series combinations, but I here's what I found.

There's a 47K and 4.7K in series between pins one and 2 for a total of 51.7K. I measured 70.7K.


Between pins 2 and 7 I should have 3300pF but measured around 4300pF.


Seems to me those are pretty far off and I should replace this network. I'll pop out K2 next and see how it measures up.
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  #37  
Old 09-11-2012, 07:03 PM
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The other networks showed similar results so I decided to just replace them all. I was curious about the internal construction and dissected a couple. The resistors are just carbon powder and the caps look like ceramic cylinders.

I rebuilt the K4 network using plastic caps and metal film resistors on a little perf board. The 0.0015 uF cap is rated for 2,000 volts like the one next to it on the main board.

Parts for the other neworks will arrive in a couple days.
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  #38  
Old 09-12-2012, 09:48 PM
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Looking good!

That's looking great Bob,
You are making me want to eventually try a predicta but I will need to work up to it with some easier sets first, that I have in the wings.
I like how the networks are looking on the board.
I have my eye on one that is within driving distance if I win the auction, but I would never have one shipped.
If I win it will have to be on display for a little while until I get up the nerve to give it a go.
Tom

Last edited by n2bew; 09-12-2012 at 09:54 PM. Reason: spelling, of course
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  #39  
Old 09-12-2012, 11:40 PM
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I like the solution to the networks, since you could not do what you did on the T&C. Looking forward to more updates as always!
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  #40  
Old 09-13-2012, 12:27 AM
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I ordered my parts from Mouser as usual, but made a mistake when choosing shipping options. I usually choose FedEx Ground if I'm in a hurry (2 days) or US Post Office (3-4 days) if I can wait a bit.

This time I choose a new option - a rather generic "Standard Shipping". When I received a shipping confirmation, it turned out to be UPS. I later did a package track with UPS and discovered they had farmed it out to the Post Office with an ETA of 10-14 days!?!

If I had just chosen the Post Office in the first place, I probably would have received my parts by now. Instead, I'll be lucky to get them next week
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  #41  
Old 09-13-2012, 03:15 PM
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Not to worry! It won't take that long...
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  #42  
Old 09-13-2012, 03:38 PM
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The service is called 'UPS Mail Innovations' and my package ETA is 9/17. If I had gone with FedEx ground it, would have arrived a week sooner at about the same cost.

Do a web search on 'UPS Mail Innovations review' and you'll find plenty of nasty feedback.
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  #43  
Old 09-13-2012, 05:19 PM
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After the Predicta is assembled, can you get access to align the IF transformers?

Carl
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  #44  
Old 09-13-2012, 06:11 PM
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Not very easily, but the cables are long enough that you can slide the chassis out a bit to make adjustments easier.
I'll probably align it while it's out of the cabinet entirely though.
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  #45  
Old 09-14-2012, 02:28 AM
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While waiting for parts to arrive, I took care of some other items.

The rebuilt electrolytics have been installed.


Also, the germanium power rectifier module has been replaced with a terminal strip and two 1N4007 silicon rectifiers.
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Last edited by bandersen; 09-14-2012 at 02:58 AM.
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