Help!!!

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Re: Help!!!

Post by jerryhawthorne on Wed Aug 13, 2014 9:47 pm

WC keep up your approach, Frank is really hanging in there and learning a lot. Slow and steady is the proper approach for someone new. Learning how a radio works with a proper approach to trouble shooting will serve him well.
I have one question not related exactly but something I have always wanted to know and discussed here. It seems that everyone suggests using an external cap on the probe of a signal generator when working on a radio. Why didn't they or did they, install a cap inside the generator at the output end.
I'm still learning.
Good luck Frank, you will get there soon with the radio singing.
Best, Jerry

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Re: Help!!!

Post by Wildcat445 on Wed Aug 13, 2014 10:18 pm

Jerry, as far as I know some signal generators have a capacitor built into the end of the probe. My concern has been that these signal generators are as old as the radios we are servicing, sometimes far older. I am concerned about the condition of the isolation cap, if any, that is built into the probe. Attempting to replace the iso cap could destroy the probe in many cases. I was taught 40 years ago to use an isolation cap on any test equipment to protect the instrument from potential damage from high voltage DC from the radio under test. I have a "tester board" made up that has a 15 amp fuse and holder, a 7.5 amp fuse and holder, a 10uf @ 450 electrolytic cap and a .01uf at 630 volt coupling cap. I use Fahenstock fasteners on each end of the fuse or cap, then attach my generator or power supply to one end and a test lead to the other. This way I save needing three hands to handle the generator probe, hold the coupling cap, and put the test lead where it needs to be. Thank you for your support, and please feel free to offer any assistance to Frank that you would care to. I hope this answered your question.

WC

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Re: Help!!!

Post by jerryhawthorne on Wed Aug 13, 2014 10:33 pm

Thanks WC, my gen did not come with any "probe". I wired up some coax to a connector to attach to the gen and terminated in a couple alligator leads. I will have to take the case off but I seem to remember a cap on the "hot" side of the of the connector on the the generator.
Come on Frank, you can do it!
Jerry

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Re: Help!!!

Post by Wildcat445 on Wed Aug 13, 2014 11:08 pm

I use an old Superior, I think a model 200-C, that came over on the ark. It has a red pregnant plastic doodad on the end of the hot lead with an alligator clip on that to attach to whatever. My stepdad had this old generator, and told me years ago that there was a line isolation cap in that probe, but that to repair it would destroy the probe. So he taught me to just use an external isolation cap. Your idea of placing one actually in the generator is better, and I think I will try that. That would save a lot of grief, and I would not forget to use it in my old age. I could still use an external one if it made me feel better. Not knowing the condition of Frank's equipment, I felt it best to err on the side of caution. He is working on a hot chassis with no iso transformer as well. Thanks.

WC

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Re: Help!!!

Post by frank1956 on Wed Aug 13, 2014 11:31 pm

Wildcat445 wrote:Frank, you would be better equipped for little surprises like this if you would buy at least a small stock of the most needed capacitors and keep them on hand.  Radio Daze has an assortment of the most needed sizes, something like 10 each, that will set you up in good enough shape that you will have a decent supply to start.  As you gain experience and figure out what you will need, you can stock up.  I buy hundreds at a time.  They are considerably cheaper in quantity.  Many times there is free shipping if you buy a quantity.  Your project will then not be held up waiting for a 30 cent part.  Good luck.

http://www.radiodaze.com/

WC

WC Thanks. I doubled up on the order I placed today for certain capacitors. I have bookmarked the site above and will be better prepared in the future.
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Re: Help!!!

Post by Wildcat445 on Thu Aug 14, 2014 10:04 am

Frank, you are doing fine. This is how we all learned. Your experience with this radio may help someone else when they are starting out. Six months from now you will be giving advice to others like an old pro. I guarantee when you hear that radio talk for the first time, it will take three weeks to wipe the grin off your face. It will be a moment you will never forget.

WC

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Re: Help!!!

Post by 75X11 on Thu Aug 14, 2014 10:35 am

Another item you may want to consider while choosing supplies would be tubing to insulate the legs of your components or other bare wiring in your sets. Here is a diverse selection of shrinkable and non shrinkable tubing.

http://www.surplussales.com/Rubber-Plastic/Sleeving-1.html
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Re: Help!!!

Post by frank1956 on Sat Aug 16, 2014 10:13 pm

Can I use a .05 @ 630 volts in place of a .01 @ 630 volt to conduct the next part of the signal generator test? I also have some .022 @ 630 volts as well. Just wondering as there was a mess up with my order and the .01 @ 630 volts did not come in as expected. Won't be until Wednesday now.
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Re: Help!!!

Post by Wildcat445 on Sat Aug 16, 2014 10:48 pm

The .022 will work.  The capacity is not as important as just using one for protection.  I sent you a PM. Be sure to open it. Thanks.

WC

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Re: Help!!!

Post by 35Z5 on Sat Aug 16, 2014 11:20 pm

Any value from probably .005 to .05 will work, but the smaller value will pass less AC which lessens chance of shock...
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Re: Help!!!

Post by frank1956 on Sun Aug 17, 2014 12:40 pm

WC, Tom,
Thanks. I will proceed with the test and let all involved know the results.

Frank
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Re: Help!!!

Post by Bill Cahill on Thu Aug 21, 2014 2:53 pm

Frank, any luck with your readings?? Is the signal generator helping you to find the problem.? You know, it could also be a loose connection, a dirty tube socket, or, a bad tube. Have the tubes been properly tested?
May be as simple as that.

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Re: Help!!!

Post by frank1956 on Thu Aug 21, 2014 4:17 pm

Bill, Have tested all the tubes and all is well there. I have not used the signal generator yet, but plan on it very soon. I will go back and double check the tube sockets.

Thanks
Frank
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Re: Help!!!

Post by frank1956 on Mon Sep 01, 2014 1:05 pm

I connected the hot lead of the signal generator in series with a .01 @630 volt capacitor to the terminal on the tuning cap where the antenna is connected, ground to chassis. The signal generator was warmed up for 30 min, radio was warmed up for 10 min. Radio dial was set at the low end of the radio dial and signal generator was set to 455khz and attenuation was set high enough to hear the tone, the signal sel was set to Int Mod AF Out. When the signal was injected into the antenna section of the tuning cap a tone was hear I rotated the tuning cap clockwise. The tone was loud and in some case just audible, but was never lost or cut out during the process.

Frank
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Re: Help!!!

Post by jerryhawthorne on Mon Sep 01, 2014 3:58 pm

Frank the set up you are using is great to check tracking by setting sig gen as you did but running it at perhaps 650khz and seeing if you get the hum at that point on the dial and again at perhaps 1500khz and see if the hum is picked up there.
Not the best setup for checking IF alignment. When you think about it you are trying to get a 455khz signal through the front end of a radio which does not tune that low. You will force some through. You might check your documentation as to the proper way to set the IF for tuning. Some do it the way you are trying but don't expect the tone to be constant across the tuning band.
Jerry

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Re: Help!!!

Post by Wildcat445 on Mon Sep 01, 2014 9:27 pm

Jerry, you are technically correct. But for purposes of talking Frank thru his first alignment, I made the statement that the intermediate frequency of the radio should be able to pass thru the radio. If he had tuned to a harmonic of the IF, the signal would come and go, again technically in intervals of the IF. When Frank turns the dial actually tuned to the IF, the tone should remain fairly constant, regardless of dial position. I made this statement so that he would have some indication of whether or not he was actually making progress. Performing my first alignment was an anxious time, but talking somebody else thru their first alignment (and fearing forgetting something important) is far more difficult. Frank has worked hard at this, so if anybody can do it, it will be Frank. Thanks,

WC

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Re: Help!!!

Post by jerryhawthorne on Mon Sep 01, 2014 9:54 pm

WC, you are correct. Perhaps aligning at the lower frequency should give the best response as it is closer to to IF frequency? If the OP has the the instructions for alignment best to follow. But your right, getting a strong harmoic will work. Some radios do require a specific place to put the sig. gen like into the If first grid.
Sorry but I have working too long on TRF radios. Thinking back, your right for most radios of the super het designs you can pump it into the antenna but don't expect the response to be flat across the dial? You will be picking up the harmonics. Fine.
Frank, time to adjust the IF transformer if you certain your sig gen is at the proper frequency.
Still, set your sig gen to any radio frequency as before, perhaps to 100kc and see if you pick it up on the dial.
Best and sorry if I added confusion to the post.
Jerry

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Re: Help!!!

Post by Wildcat445 on Tue Sep 02, 2014 12:06 pm

Frank, have you made any progress?

WC

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Re: Help!!!

Post by frank1956 on Wed Sep 03, 2014 2:24 am

WC, I am waiting on my alignment tools. Should be in this week and I will get started. I started another thread in test equipment in regards to the alignment.

Frank
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Re: Help!!!

Post by Wildcat445 on Wed Sep 03, 2014 10:37 am

Got it.  It will be best to keep a discussion on you radio confined to this thread. If you want to talk about test equipment, then you can continue the other thread. Thanks.

WC


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Re: Help!!!

Post by frank1956 on Wed Sep 03, 2014 11:53 am

WC, This is where I started might as well finish it here cheers
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Re: Help!!!

Post by Wildcat445 on Wed Sep 03, 2014 12:10 pm

After you get your alignment tools, we will see if we can get that baby singing. Very Happy

I had not gotten any emails from you lately, so I was afraid I had made you mad or something. I have been being pretty hard on you, and feared I had crossed the line. You are doing great, Frank. I wish everybody starting out was as determined as you are.

WC

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Re: Help!!!

Post by frank1956 on Wed Sep 03, 2014 12:18 pm

Was just waiting on the correct tools. Since I have none might as well do it right, since this will not be my last project. Hopefully they will be here tomorrow or Friday.


Frank
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Re: Help!!!

Post by willy3486 on Wed Sep 03, 2014 1:18 pm

I have been following this when I can. I noticed you asked about tools needed. I sent you a email here to a link I have on how to make a signal tracer out of a old 9 volt or similar radio. I made one of these back in the mid 80s and its one of my most used items on old radios. I do most of my repairs with only a tracer and a signal generator . If you don't have a radio I bet a set of old amplified computer speakers would work as well. Anyway if you need a tracer check it out.

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Re: Help!!!

Post by frank1956 on Thu Sep 04, 2014 5:12 pm

WC, Tom,
The alignment tools came in today and I am ready to being the radio alignment. I am a little fuzzy  Question  on the second part of the alignment the grid for 12BE6 tube, I believe it is the number 5 pin from what I have been able to find on line. Any help would be appreciated.

Thanks
Frank
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Re: Help!!!

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