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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Tue 14, 2015 10:21 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 19126
Location: Warner Robins, GA
There is a B12A (duodecal) socket

here

http://www.steampunkalchemy.com/en/nixi ... -driver-ic

and here

http://www.leedsradio.com/parts-sockets.html


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Wed 15, 2015 4:46 am 
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Posts: 2860
Location: Tucson, Arizona U.S.A.
Quote:
I did not think about having to rotate the CRT. I'll have to think on that one. The way it was installed there wasn't going to be any rotation...

Sure there could be. Loosen the clamp, rotate the tube to align the trace, tighten the clamp. That's another reason to not use an adhesive.

Jim Mueller


No sir, the black stuff is hard as a rock and molded to the bracket and tube base. it's going to be a pain in the neck to get that bracket off and remove the "rubber" from the base.

True now, but when it was new rotation was easy. You want to restore that.

Jim Mueller

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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Wed 15, 2015 5:10 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
Jim Mueller wrote:
Quote:
I did not think about having to rotate the CRT. I'll have to think on that one. The way it was installed there wasn't going to be any rotation...

Sure there could be. Loosen the clamp, rotate the tube to align the trace, tighten the clamp. That's another reason to not use an adhesive.

Jim Mueller


No sir, the black stuff is hard as a rock and molded to the bracket and tube base. it's going to be a pain in the neck to get that bracket off and remove the "rubber" from the base.

True now, but when it was new rotation was easy. You want to restore that.

Jim Mueller


Agreed. Do you think felt or something like felt would work or is that a fire hazard? Heat may be why the rubber crytalized

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It's hard to solve an equation if every term is an unknown.

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Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Wed 15, 2015 1:01 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
Foam rubber can do that. Felt should work.


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Wed 15, 2015 1:03 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 13788
Location: Fernandina Beach, FL
Adding to Alan's post, yes, felt was used around CRTs in the past. If I remember properly, my Dad's Heathkit scope had felt around the face of the CRT.

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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Thu 16, 2015 12:32 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1036
Location: 98802
Yes... felt or a strip of rubber or something.

I can see that it is attached to both the bracket and the tube base *now*, but I'd bet almost anything it wasn't built that way. When it was new, you should have been able to loosen the clamp to move the tube.


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Thu 16, 2015 1:40 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
Good... Now I have a solution for that. The tube socket is being a pita. I can find them in China but not in the US so far. The old one isn't in bad shape but I'd rather replace it

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It's hard to solve an equation if every term is an unknown.

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Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Thu 16, 2015 5:07 am 
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Location: Tucson, Arizona U.S.A.
CRTs like this dissipate very little power in a large envelope. As a result, they don't get very hot, just a little warm.

Your rubber pads just deteriorated from age.

Jim Mueller

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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Thu 16, 2015 11:51 am 
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Posts: 19126
Location: Warner Robins, GA
Mike6158 wrote:
Good... Now I have a solution for that. The tube socket is being a pita. I can find them in China but not in the US so far. The old one isn't in bad shape but I'd rather replace it


http://www.leedsradio.com/parts-sockets.html

That one seems to be in the US unless that seller is out of stock.


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Thu 16, 2015 1:33 pm 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
Tube Radio wrote:
Mike6158 wrote:
Good... Now I have a solution for that. The tube socket is being a pita. I can find them in China but not in the US so far. The old one isn't in bad shape but I'd rather replace it


http://www.leedsradio.com/parts-sockets.html

That one seems to be in the US unless that seller is out of stock.



I must have typo'd the search value when I checked last time. They show two but one is marked $0.00 and I completely missed the one that they have with a price on it even though it's the first one. Anyway, I send them an email to see if it was available and how to buy it

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It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Thu 16, 2015 11:12 pm 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
Tube Radio wrote:
Mike6158 wrote:
Good... Now I have a solution for that. The tube socket is being a pita. I can find them in China but not in the US so far. The old one isn't in bad shape but I'd rather replace it


http://www.leedsradio.com/parts-sockets.html

That one seems to be in the US unless that seller is out of stock.


Winner winner chicken dinner :) He had, and recommended if rebuilding for longevity, an Eby B12A NOS so I bought it. I'm getting close to putting it back together

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It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Thu 16, 2015 11:26 pm 
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Posts: 19126
Location: Warner Robins, GA
Awesome


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Sun 19, 2015 12:10 pm 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
The CRT socket arrived. It's a nice socket. I'm still waiting on a few resistors but it shouldn't be too much longer.

I had to test some tubes in a T3 signal tracer yesterday. While I was testing, I figured that I may as well test all of the tubes in Miss Piggy. Two of the tubes tested bad. It's got 10 tubes in it. Three 12AU7A's, one of which failed a shorts test. Ouch... not the cheapest tube in the pile... It has two rectifiers. A 6X4 full wave rectifier for the low voltage supply with a 6C4 voltage regulator and a 1V2 used as a half wave rectifier for the high voltage supply for the CRT. The 1V2 failed a shorts test. More parts... but I think, maybe, hopefully, that's about it for parts.

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It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Sun 19, 2015 2:15 pm 
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Joined: Feb Tue 07, 2012 9:32 pm
Posts: 1789
Location: Middlesex,NJ
HI MIKE:

PROGRESS.SLOW BUT SURE.

IT IS UNUSUAL FOR THE 12AUT & 1V2 TO SHOW SHORTS.
THE 12AUT HAS A CENTER TAPPED FILAMENT WHICH IF THE CONTROLS ARE NOT SET PROPERLY WILL INDICATE A SHORT.

I HAVE ALSO FOUND THAT ONE TUBE TESTER MAY INDICATE A SHORT,ANOTHER WILL NOT.

I HAVE NEVER ENCOUNTERED A SHORTED 1V2.

I SUGGEST DOUBLE CHECKING THE SETTINGS AND SEE IF THERE ARE ANY NOTES.

SOME TUBE TESTERS DO NOT HAVE ANY SPECIFIC NOTES.

WHAT TUBE TESTER ARE YOU USEING?

WALTER-W2WIQ


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Sun 19, 2015 2:42 pm 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
W2WIQ wrote:
HI MIKE:

PROGRESS.SLOW BUT SURE.

IT IS UNUSUAL FOR THE 12AUT & 1V2 TO SHOW SHORTS.
THE 12AUT HAS A CENTER TAPPED FILAMENT WHICH IF THE CONTROLS ARE NOT SET PROPERLY WILL INDICATE A SHORT.

I HAVE ALSO FOUND THAT ONE TUBE TESTER MAY INDICATE A SHORT,ANOTHER WILL NOT.

I HAVE NEVER ENCOUNTERED A SHORTED 1V2.

I SUGGEST DOUBLE CHECKING THE SETTINGS AND SEE IF THERE ARE ANY NOTES.

SOME TUBE TESTERS DO NOT HAVE ANY SPECIFIC NOTES.

WHAT TUBE TESTER ARE YOU USEING?

WALTER-W2WIQ


HI WALTER,

I USE AN EICO 667. I'M GOING TO TEST THE TUBES AGAIN THIS MORNING. IT WAS LATE WHEN I TESTED THEM LAST NIGHT. I SAID THEY FAILED A SHORTS TEST AND IT COULD HAVE BEEN MERIT. I TESTED (3) 12AU7'S. IT'S A TWO PART TEST AND I TESTED EACH TUBE BEFORE I CHANGED SETTINGS. ONLY ONE FAILED.

I'LL POST TESTER SETTINGS AND RESULTS WHEN I FINISH THE RE-TESTING

THANKS FOR THE HELP

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It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Sun 19, 2015 2:49 pm 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
I ALREADY FOUND SOMETHING WALTER. THE PINS ON THE "BAD" 12AU7A HAD "GREEN STUFF" ON THEM. I CLEANED IT WITH DE-OXIT AND THIS TIME WHEN I PUT IT IN THE TESTER THE FILAMENTS LIT. THEY DIDN"T LIGHT UP LAST NIGHT.

_________________
It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Sun 19, 2015 2:52 pm 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
:D PIN CORROSION WAS THE PROBLEM WITH THE 12AU7A. I NEVER THOUGHT ABOUT CHECKING FOR CORROSION. THE TUBE TESTED VERY GOOD. I'LL CHECK THE OTHER TWO TUBES AND REPORT BACK

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It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Sun 19, 2015 3:39 pm 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
I HAVE TWO SETTINGS CHARTS. THE ROLL CHART IN THE 667 AND A NEWER, PRINTED CHART THAT CAME WITH THE TESTER. THE NEW CHART HAS 7511 IN THE UPPER LEFT CORNER.

I'M GOING TO INCLUDE THE 1V2 SETTINGS FROM BOTH CHARTS BECAUSE THEY ARE DIFFERENT. I'LL BOLDFACE THE ITEMS THAT ARE DIFFERENT ON THE OLD DATA

NEWEST DATA
FILAMENT: 0.625
GRID: 0
PLATE: 100
LEVERS: 6662166 641111
V: 2
S: 4
LEAK: 9
MERIT: 9

NOTE: GOOD TUBE READS ABOVE 2O

ROLL CHART DATA
FILAMENT: 1.4
GRID: 0
PLATE: 100
LEVERS: 6661266 641111
V: 2
S: 4
LEAK: 9
MERIT: 9

NOTE: NONE

FIRST TEST ON THE 1V2 SHOWED NO LEAKAGE BUT ABSOLUTELY NO MOVEMENT ON MERIT. THE FILAMENTS WEREN'T GLOWING THAT I COULD SEE. AT .625V I DIDN'T REALLY THINK I WOULD SEE THEM GLOWING. SO, ON A WHIM I CHECKED THE ROLL CHART. FILAMENT VOLTAGE SHOWED 1.4. SINCE THE TUBE LOOKED DEAD ANYWAY I TRIED 1.4 AND THE OTHER SETTINGS. THE FILAMENTS GLOWED. I RESET THE LEVERS AND STARTED THE TEST BUT THE METER MOVED WAY TOO FAST FOR MY COMFORT AND I STOPPED THE MERIT TEST.

NOW HERE'S THE INTERESTING PART. I PUT THE SETTINGS BACK TO THE NEW VALUES AND TESTED THE TUBE. THIS TIME MERIT CAME UP INTO THE GREEN AREA AND THEN SLOWLY DRIFTED DOWN BELOW GREEN BUT ABOVE 20. I TOUCHED THE TOP OF THE TUBE AND IT DROPPED ALMOST TO 0. LET GO AND IT SLOWLY COMES UP ABOVE 20. WIGGLING THE TUBE GETS THE SAME RESULT. I LET IT SIT FOR A WHILE AND WHEN I DID THE MERIT TEST IT TESTED GOOD. I GUESS I'LL GIVE THAT ONE A TRY TOO.

-----------

THE TESTING FOR THE 12C8 FOR THE SIGNAL TRACER DIDN'T GO SO WELL

SETTINGS
FILAMENT: 12.6
GRID: 26
PLATE: 22
LEVERS: 1141632 111115
V: 4
S: 3
LEAK: 3-6-8-C
MERIT: 3

FILAMENT: 12.6
GRID: 7
PLATE: 25
LEVERS: 1165562 111116
V: 4
S: 6
LEAK: 4-6-8
MERIT: 4-5

RESULTS
1ST 1/2 TEST
6: LEAKAGE READING: ALMOST 0 (ALL THE WAY TO THE RIGHT)
THE REST WERE FINE.

NO MERIT TEST WAS DONE DUE TO BAD LEAKAGE READING

2ND 1/2 TEST
8 LEAKAGE READING: 2.5M
THE REST WERE FINE
MERIT: NO MOVEMENT OF THE NEEDLE

SO 2 OF THE 3 TUBES DID TEST OK.

THE 12AU7A HAD PIN CORROSION THAT ONCE CLEANED LET IT TEST GOOD.

THE 1V2 MAKES ME WONDER BUT IN THE END IT TESTED OK

THE 12C8 SEEMS TO BE BAD.

_________________
It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: Apr Sun 19, 2015 4:29 pm 
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Joined: Feb Tue 07, 2012 9:32 pm
Posts: 1789
Location: Middlesex,NJ
HI MIKE:

PROGRESS!!!

IT SEEMS THERE ARE SEVERAL PROBLEMS.

DIFFERENCE BETWEEN CHART SETTINGS.

POSSIBLY MORE DIRTY PINS.

SOCKET PINS TOO LOOSE AND NOT ALWAYS MAKEING GOOD CONTACT.
7&9 PIN SOCKETS ARE FAMOUS FOR THAT.THOSE 2 SOCKETS ARE THE MOST USED AND OVER TIME SPREAD DUE TO THE OPERATOR WIGGLEING THE TUBE TO REMOVE IT.
I USE A JEWELERS SCREWDRIVER AND FORCE THE 2 SIDES OF THE CONTACT CLOSER TOGETHER.

THE 1V2 SHOULD NOT DROP ON MERIT.

WALTER-W2WIQ


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 Post subject: Re: Knight Wideband Oscilloscope
PostPosted: May Sun 03, 2015 3:16 pm 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 1975
Location: Weimar, Texas
In order to install the 7 pin socket that I have for the 6X4 in the chassis I am going to have to open the hole up to 3/4". I have a set of chassis punches so that's not an issue. Does anyone see a problem with the type of socket that I selected. Found is a better word than selected. I wanted something with the same bolt pattern and his was all I've found so far. The 9 pin socket for the 1V2 is the same type and it fit into the original hole just fine.

The blue material is some kind of plastic and I wasn't sure if the tubes would run hot enough to cause problems. They sure do hold good.

_________________
It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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