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Author Topic: Globe King 500 B  (Read 3803 times)
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WD4TC
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« on: September 09, 2009, 11:51:17 AM »

 Hello to the Group.  I have acquired a  GK-500 B to sit next to my 500A and as I started to go thur the Modulation deck I got to thinking about mods to it..Is there or has anyone done a mod to there deck and is it worthwhile ? I am thinking I want to do away with the couplets and  eliminate the 6al5 compression tube and  fatten up the audio on this one.I may be thinking Wrong ?..TNX in advance for any info..Tim..WD4TC
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Tim...WD4TC 
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W3GMS
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« Reply #1 on: September 11, 2009, 11:10:39 PM »

Hi Tim,
You may want to check with Tim, W3TIM since I know he has a GK-500.  I am not sure how extensives his mods were but his always sounded good on the air.  I was going to work with him on some more extensive mods but he got busy with some other projects and it never came to pass.  The rig does not have a lot of margin when it comes to pushing the audio.  I would think that you would be able to improved the audio response, realizing that you will probably never get 130% positive out of it.  Some simple improvements such as what you mentioned is where I would start.  If you email me the schematic I can give you some suggestions.
Joe, W3GMS
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Simplicity is the Elegance of Design---W3GMS
k4kyv
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Don
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« Reply #2 on: September 12, 2009, 03:06:00 AM »

I would definitely recommend getting rid of the couplettes and replacing each with a conventional plate resistor-coupling cap-grid resistor combination.  Those things  were designed to deliberately limit frequency response to carbon mic/telephone quality audio.
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WD4TC
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« Reply #3 on: September 12, 2009, 11:24:42 AM »

  Thanks for all the info. As I got into it T-3 (audio driver transformer ) was kaput so it's out and on the way to Gary so I just do the rest and weight on it to return ! I suppose in the mean while I go to the A model  and finish redoing the building and get back on the Air after all been missing it for a while...Tim...WD4TC....


* DSCF1156.JPG (1986.75 KB, 3264x2448 - viewed 374 times.)
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Tim...WD4TC 
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N2DTS
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« Reply #4 on: September 12, 2009, 09:20:27 PM »

Are there many glob king 400 rigs around?
Bruce, WA3JVJ has one he used to use and it seemed like a good rig by wrl standards.
I dont hear any 400's on the air any more.

On a side note, there seems to be no reason to bias 811a's even at 1500 volts.
I have run them that way for years, the plates don't show color, resting current is not very high.
Maybe bias is needed in ccs service, but does not seem to be needed the way I use them.
 
Brett
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K5UJ
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« Reply #5 on: September 14, 2009, 07:32:29 AM »

That GK in the photo the one you just acquired?  It looks very nice.   A 400 went on eBay a few months ago for more than I expected--either $600 or $900, I can't remember which. 

Rob
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WD4TC
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« Reply #6 on: September 14, 2009, 09:29:18 AM »

  Yes Rob it is.. This one was priced right and NO mods (all original) and really clean.I just had to buy it.I have a hard time passing some transmitters even if I already got one... Tim..WD4TC....
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Tim...WD4TC 
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