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Author Topic: COLLINS 30L-1: YEAR? FUSES?  (Read 1842 times)
N6QWP
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Posts: 160




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« on: December 31, 2016, 05:46:16 PM »

HAVE A COLLINS 30L-1 SERIAL NUMBER 11120.  THE FUSES ON REAR PANEL ARE MARKED 6 AMP INSTEAD OF 8 AMP WHICH LATER MODELS HAVE, I BELIEVE?  

DOES ANYONE KNOW HOW TO TELL THE YEAR IT WAS MADE?  WHAT YEAR DID THEY CHANGE THE RATINGS OF THE FUSES?  WHY?  SHOULD I SWITCH TO 8 AMP FUSES?

IT HAS NEW CAPACITOR AND DIODE BOARD.  HIGH VOLTAGE AT 117VAC READS 2000VDC AND IDLING CURRENT WHEN KEYED WITHOUT ANY DRIVE READS 100 MILLIAMPS.  WONDERING HOW THIS COMPARES WITH OTHER 30L-1'S?  PLATE VOLTAGE SEEMS A BIT HIGH.....IDLING CURRENT SEEMS A BIT LOW.

ANY THOUGHTS?  THANX

« Last Edit: December 31, 2016, 05:52:10 PM by N6QWP » Logged
KE7YD
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« Reply #1 on: December 31, 2016, 10:00:02 PM »

Check out this organization and web page.  The different versions of the 30L1 are listed along with service bulletins.

The manuals will answer all your questions.

http://www.collinsradio.org/cca-collins-technical-archives/collins-radio-equipment-manuals/

Ken
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N6QWP
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« Reply #2 on: January 01, 2017, 06:32:58 AM »

HI KEN, THANX FOR YOUR REPLY.  HAVING PERUSED THE MANUALS SUPPLIED ON THE COLLINS WEBSITE THAT YOU GAVE.  STILL UNABLE TO DETERMINE AGE OF THE ABOVE DESCRIBED 30L-1.  I SUPPOSE THAT IT MIGHT BE PRIOR TO 1962 WHEN THE 5TH EDITION OF THE MANUAL WAS FIRST PUBLISHED INDICATING REPLACING THE 6 AMP FUSES WITH 8 AMP ONES.

I GUESS WHEN THEY PUT OUT THE 1962 UPDATED SERVICE MANUAL, BY THEN THEY WOULD HAVE ALSO CHANGED THE MARKINGS ON BACK PANEL FROM 6 AMP TO 8 AMP?  THEY DO NOT HAVE EARLIER EDITIONS OF THE MANUAL IN THE ARCHIVES, SO STILL UNABLE TO GO BACK IN TIME TO GET A PRODUCTION DATE.

HOPING SOMEONE WITH A SIMILAR SERIAL NUMBER MIGHT ENLIGHTEN ME IF THEY HAVE BEEN ABLE TO DETERMINE THE AGE OF THEIR UNIT--EITHER EARLIER OR LATER THAN 1962.
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N6QWP
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Posts: 160




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« Reply #3 on: January 01, 2017, 08:03:56 AM »

I JUST READ THAT THE 30L-1 WAS FIRST PRODUCED IN 1961?  MIGHT THAT INDICATE THAT ONE THAT STILL HAS 6 AMP MARKINGS ON REAR PANEL WOULD BE EITHER 1961 OR 1962?  SERIAL NUMBER SEEMS HIGH IF IT MEANS THAT THEY REALLY PRODUCED THAT MANY SO QUICKLY?  OR, WOULD THEY CONTINUE TO USE OLD SILKSREENING TEMPLATES AFTER THE SERVICE BULLETIN OF 1962?

ALSO, STILL HOPING TO HEAR FROM ANYONE ABOUT THE LOW IDLING CURRENT THAT I AM GETTING. THE SERVICE BULLETIN DESCRIBED A MODIFICATION REDUCING THE IDLING CURRENT FROM 130 TO 110 MILLS IN ORDER TO REDUCE HEAT FROM THE TUBES.  WONDERING IF 100 MILLS MIGHT BE A BIT TOO LOW AND PRESENT ANY PROBLEMS?  

ANYONE ELSE HAVE SIMILAR READINGS OR EXPERIENCES?  THOUGHTS?
« Last Edit: January 01, 2017, 08:28:32 AM by N6QWP » Logged
KE7YD
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« Reply #4 on: January 03, 2017, 10:55:14 AM »

Take a look at the bias supply in the schematic.  The bias supply is shown at the bottom of the secondary of the transformer and check the value of the associated resistors and the caps.  the bias hold be 110 mA but remember that the component tolerances are +/- 10%.  It's tough to read exactly 110 mA on a meter that has it's finest resolution of 100 mA increments. 
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W8JX
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« Reply #5 on: January 03, 2017, 03:22:55 PM »

Take a look at the bias supply in the schematic.  The bias supply is shown at the bottom of the secondary of the transformer and check the value of the associated resistors and the caps.  the bias hold be 110 mA but remember that the component tolerances are +/- 10%.  It's tough to read exactly 110 mA on a meter that has it's finest resolution of 100 mA increments. 

110 ma is a lot of current in that at about 1800 volts it pretty much puts 811 tubes at max rated continuous dissipation at zero signal.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
KE7YD
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« Reply #6 on: January 03, 2017, 10:32:42 PM »

That is the current spec'd after SB 3 came out in April 1962. Prior to that, it was 130mA key down, with no excitation.  The comment on the reason for the SB from Collins was to lower plate dissipation.... No kidding! 

I needed new tubes in mine when i bought it, so it received 4, 572b's.  They have much more plate dissipation capability.
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W8JX
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« Reply #7 on: January 04, 2017, 04:08:50 AM »

That is the current spec'd after SB 3 came out in April 1962. Prior to that, it was 130mA key down, with no excitation.  The comment on the reason for the SB from Collins was to lower plate dissipation.... No kidding! 

I needed new tubes in mine when i bought it, so it received 4, 572b's.  They have much more plate dissipation capability.

My Dentron Clipperton QRO (replaced Clipperton L) idles at 70ma in CW/1900V setting and 120ma in SSB/2700V setting.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
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