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Author Topic: Globe King 500 repair and restoration review  (Read 48377 times)
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ke7trp
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« on: April 18, 2009, 06:42:06 PM »

I wanted to make a post in hopes that someone down the line would search and find this information usefull in restoration of a Globe 500. Many of you have helped me and know the story but I would thought it would be worthwhile to type up some documentation for the group.

My Globe king 500C was not working when I purchased it. The owner before me installed the wrong tubes in the modulator Rectifier sockets. This sent AC voltage through the mod deck.

Modulator:
1. Every tube in my deck was bad. The 811s where shorted. New tubes installed.
2. The HV power trans for the modulator deck was shorted. I got a used one from W0VMC robert. W8QBG George came over to my house and helped me wire it in.. What a guy!
3. I converted to Solid state plug in Rectifiers. Now with 1600 Volts on the 811s.
4. Replaced all old capacitors with higher values.
5. Performed the W0VMC Modulator Speach amp kit.  Kit came with Schematic and all parts for hi fi audio. No more couplates.
6. His mod Also allows me to use the Phone patch cable  for use with external audio gear bypassing some of the preamp tubes.
7. Replaced HV connector on back. Used to have old Standoff types. I used Screw on Amphenols from Henry radio with Spark plug cable.
8. Cleaned switches and pots with Deoxit
9. PTT was not working. Found that the Electrolytic near the Selenium rectifier was bad. Replaced cap and used 1 amp diode in place of rectifier.
10. Replaced 6UF Oil can cap in HV section to a new 12 UF from W0VMC Robert. It fits in, I had to extend the clamps with custom made brackets.

At this point The mod deck was up and running.

Power supply Deck:

1. Cleaned chassis
2. Cleaned relays.
3. Replaced 866s with plug in solid state diodes.
4. Replaced Broken 866 plate caps.
5. Replaced Cracked power cord with Large side cable and large high amp plug.
6. Replaced various Paper caps.
7. Replaced High voltage standoffs with Amphenol Screw type from Henry radio.
8. I had a Burned Relay contact on the PTT relay. I unscrewed the contact "stack" and flipped them so I had a new contact in use.

At this point, the deck was now safe and working.

RF deck:

1.Replaced all paper Caps in screen supply and through out the deck.
2. Found Cracked 500PF Doorknob.  Replaced with 1000PF unit.
3. Found Burned Parsitic Resistor on 6146 and a dead tube. Replaced both.
4. Cleaned Tank coils with Tarnex metal polish.
5. Replaced the Screen Rectifier tube with new one.
6. Found one side of the 12ax7 dead. Replaced with new tube
7. Replaced Screen bypass cap with Silver mica block style cap to ground 1000PF (w0vmc mod)
8. Replaced Filiment bypass caps (005s) with .01 large diam caps to ground (w0VMC mod)
9. Cleaned Switches and controls with Deoxit.
10. Replaced HV standoffs with scew on types from Henry radio.


As you can see, This was a basket case.  After getting the rig up and running I found I could not load to 330 MA. I could reach 280 to 300.  Power output was about 250 to 290 watts AM on a Bird 43.

I had one melt down about a month into useing the rig.. The 6CB6 tube shorted. This is the VFO Buffer tube that drives up to the RF deck. This tube cased the Solid state diodes on that supply to fail. A new tube and a 5R4 plugged in got the rig back up and running.. Now I can load to 330MA.  Its imperative that the VFO has enough drive or you will never get full output. Check or swap the 6CB6 tube and the 6au6 tube out with others until you can reach 330ma. Power output jumped to 340 to 350 watts AM after this at 330MA.

Later, I changed the 4-400 bypass caps. They are WAY to small for the job. They used tiny little disk caps. Mine where dark in color from the heat. w0vmc told me to change them and it made a big difference in power and audio response just as he said it would. Now with the .01s on the filiment and the 1000PF mica on the screens Power output is now 375 watts at 330 MA. If you turn the Grid Drive up a bit it will do 400 easy. I run it around 320MA at 350 watts with a Grid of 15 ma. 

Its important to go back and tune the Buffer knob for max plate current. This is stated in the manual. If you forget this you might be leaving some power on the table.

I run my Globe king 500C on a Seperate 30 AMP wall box with number 6 cable to a 30 amp breaker. This seemed to really help. The standard wall socket is not enough really. At least not in my house. Very stiff supply and it shows in my output.

I run a Behringer 802 mixing board.. Cost $69.  I also run a Marshal MXLV57M large diaphram condesner micphrophone. This mic requires 48 volts from the mixer. This caused me to buy the 802 mixer. The Drawback is that the 802 DOES NOT Have high impedance output. It has the 1/4 jacks but in the manual it states 150 ohms out. This resulted in low Audio. I purchased a Low to High impedance matching Transformer and a Right angle 1/4 inch plug. This matched the 802 to the high impedance on the modulator deck. Just buy a mixer with high impedance out.

Future mods?  The only thing that stands out is the HV Oil can cap. Its only 4UF. I woud like 10 to 12 UF in there and at least 3 people told me to get at least 10UF.  I have purchased some 10 and 12 UF caps and will try to get one of them in.

Results:

When swept at the mixing console to the modulator deck with 20hz to 20,000HZ, the audio is Flat from 20HZ to 9000. Its 3 DB down at 10,000 and past 10 it rolls off hard.  Not bad!

Power output is now 375 watts At 330MA. Modulated 100% it actualy goes forward to 400 RMS on the bird 43.


Many, many people on this board have helped me. I am very greatfull for all of those who have helped!  Hopefully someone will come to this site with a Globe 500 that needs a list of things to check and this post will help! I am no expert.. I have basic skills. Many of these people where very patient with me during this project!

Ke7TRP
Clark




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w3jn
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« Reply #1 on: April 18, 2009, 06:56:51 PM »

Outstanding, Clark!

You gotta wonder about rigs like that.  Most times one things craps out and the rig gets shelved.  This one sounds like it was a trailer park after a tornado hit.

BTW I didn't get your turret out today, I went to the York PA 'fester instead.  Will get it out this week sometime, depending on when I can sashay over to the post office.
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N3DRB The Derb
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« Reply #2 on: April 18, 2009, 10:54:24 PM »

and what all you learned during the process is priceless.
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #3 on: April 20, 2009, 09:54:03 PM »



Any after pix?
Any before pix?

 Grin  Grin

We love pix!!

           _-_-bear
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ke7trp
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« Reply #4 on: April 20, 2009, 10:25:05 PM »

I did very little cosmetic. This was just to get the rig up and running. I plan on painting the Chassis back to Hammer tone grey. Here are some pics of it though!

Clark


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* Photo_031509_003.jpg (384.39 KB, 1280x1024 - viewed 800 times.)
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Todd, KA1KAQ
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« Reply #5 on: April 21, 2009, 11:10:26 AM »

Always liked the Glob Queens, nice size and layout. Looks the way a table top transmitter should look, although the table better be stout.

Derb's absolutely right about the learning part: the symptoms and problems will vary from set to set, but the knowledge you gain along with the support and encouragement such a post brings to others is priceless. Obviously it wasn't a simple case of having the cabinet powder coated and claiming a full restoration!  Wink

Nice work, Clark.

BTW - is that a halogen lamp in the corner, and if so - does it raise hell with your reception?

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ke7trp
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« Reply #6 on: April 21, 2009, 01:39:21 PM »

That a king!  The Queen is the 400 Smiley

Thats a Floresent lower power lamp. Its just the camera acting up. Our power company gave us those for free so I installed them. No difference on or off on recieve.  Its not variable.. Just off and on.

I wish I had some nice metal tables or a desk to put it on.  It will have to be on the floor for now!

Clark
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« Reply #7 on: April 22, 2009, 07:26:42 PM »

Clark, the turret went out today parcel post, expect 8-10 days.
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« Reply #8 on: April 24, 2009, 12:04:57 PM »

I wish I had some nice metal tables or a desk to put it on.  It will have to be on the floor for now!

Apparently it's a well-kept secret, but shouldn't be: check your local state or gov't surplus sales site for some excellent steel tables at very reasonable prices, Clark. If you saw the post I made in QSO about my radio room project, it shows one of the two tables I picked up. Think I paid $25 for one and $35 for the other. Steelcase, AllSteel and others made these for commercial use, and they are quite stout. Some have Formica tops, some have the same rubber found on the Johnson Viking KW desk. I go with the rubber top since they are more in keeping with the age of the gear and things stay put. Not only that, they sell for less since most prefer the Formica tops for writing and so on. Both of mine have adjustable leveling feet, and a nice sized drawer too, for odds 'n ends like connectors, hardware, whatever.

You can also find them online at some of the retro furniture sites. Just make sure you're sitting down, as $700 and up seems to be typical pricing.

If you can score one of the large metal conference tables, well then you'll be livin' in the tall cotton! Those things are sweet, but quite hard to find.

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ke7trp
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« Reply #9 on: April 24, 2009, 12:10:43 PM »

Ok thanks.. I have a friend that attends all those auctions. I will check the online ones.  Old metal tables would be sweet.  I want the one my 9th grade Science teacher had. LOL 

Ok..  Onto the cosmetic restoration of the Globe king 500.   I purchased the sander, sad paper, Metal primer, and Grey hammer tone paint yesterday.  I am going to pull it all apart in a little while and get started. The hammer tone paint looks a bit darker then the original but its the best I could find.  I also got some Red paint and masking tape. I am going to tape off and repaint the Red stripe on the two aluminum bar pieces.

Clark
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nq5t
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« Reply #10 on: April 24, 2009, 01:07:21 PM »


5. Performed the W0VMC Modulator Speach amp kit. 

Can you share the information on the VMC changes (speech amp, other)?

Grant/NQ5T
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ke7trp
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« Reply #11 on: April 24, 2009, 01:14:21 PM »

You can ask Robert for it. I purchased it as a Kit with Schematic and all the parts. This made it easy for a lite skilled guy like myself. It was cheap and worth it. 

Clark
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ke7trp
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« Reply #12 on: April 26, 2009, 01:05:32 AM »

Cosmetic restoration is nearly complete. 

I chose to not repaint the face plates and resilk screen. The faces are pretty nice as is so we left that alone. This weekend we sanded the Bud case down to metal. We used an orbital electric sander with 100 grit. Then 150.

After this, we washed the case and let it dry. 

We primed the case and then used Hammer tone paint.  This paint came out MUCH darker then the can stated and darker then the original hammer tone by a mile.. Oh well.. It sure looks fantastic in person though!  The old case as pictured above was painted with Silver paint and it was a horrible paint job.

We polished the two aluminum bars at the top and bottom and put them back on the case.  I am going to replace all the screws with SS hardware tomorrow. I am going to call this transmitter done now.

Here are pictures.  Keep in mind that for some reason, the flash on the camera causes patches to show on the case. Whatever is in the hammer tone paint is reflecting the light back.  This case looks smooth and solid color in person from your eyes. I tried all different methods to try to get clean photos..  Its just wonderfull in person!

Clark


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* DSCF3374.JPG (202.71 KB, 1296x972 - viewed 782 times.)

* DSCF3375.JPG (180 KB, 1296x972 - viewed 819 times.)
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ke7trp
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« Reply #13 on: April 26, 2009, 01:06:26 AM »

more pics


* DSCF3372.JPG (206.28 KB, 1296x972 - viewed 725 times.)

* DSCF3378.JPG (232.49 KB, 1296x972 - viewed 788 times.)
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ke7trp
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« Reply #14 on: April 26, 2009, 01:28:08 AM »

I forgot to add:

When I had the 500 apart, I replaced the 4uf Oil can cap in the HV power supply.  I installed a 10 UF at 3000 volt unit. Same dimensions. It went right in. 

Now, The Radio does 125% positive Modulation. I had to recalibrate my scope. The Bird 43 RMS meter now goes forward nearly 100 watts when I talk. There must have been some major sag on that supply with the old 4UF cap. It made a world of difference.

Clark
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kc6mcw
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« Reply #15 on: April 26, 2009, 09:07:19 PM »

Looks real good Clark. Very clean. I also noticed the big rig wasnt sitting there in the purple room. Does that thing have wheels on it? I gotta hear that thing since you added more C.


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ke7trp
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« Reply #16 on: April 27, 2009, 01:37:27 PM »

I was not on this weekend. I came down with the Flu over night. Worst case I have ever had.  Feeling better this AM. Finally got some food down.

The Big transmitter is on wheels yes.  We rolled it outside to clean it out. Its drying in the backyard sun.  This week, I am going to plug it in and see if it comes up.

Clark
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« Reply #17 on: April 27, 2009, 03:57:20 PM »

I was not on this weekend. I came down with the Flu over night. Worst case I have ever had.  Feeling better this AM. Finally got some food down.

The Big transmitter is on wheels yes.  We rolled it outside to clean it out. Its drying in the backyard sun.  This week, I am going to plug it in and see if it comes up.

Clark

I forgot to add, on the subject of the parasitic suppressors on the monster.  You can also get a plate current / voltage reading, and call/email Rich Measures.  He can sell you a toaster wire suppressor kit that will work great.

--Shane
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ke7trp
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« Reply #18 on: July 29, 2009, 01:06:56 PM »

Just and update to the original Restoration.. In case someone comes along that is restoring a King 500.


I ditched the 6al5 clipper stage.  Simple remove the tube and Connect a jumper from the Cathode Pin 5 to the Suppressor Grid of Pin 3 on the 6sJ7 preamp tube.  This helped alot with the audio.

Next,  I installed a 2.2 Meg resistor from the mic jack to the Grid pin of the 6SJ7.  I used a 500K from the Grid pin to Ground.  This matched the D104 much better. The Stock 47K is better for a dynamic mic.

For some reason, You cannot get past 75% to 80% mod with the Globe king and a D104.  Many of complained about this over the years. I found that if I run a powered D104 I can get over 100% without flat topping.  Run the D104 about half way and keep the Gain control on the king down around 3.  The difference is amazing. The First tube does not have enough gain to hit 100%.

Clark
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« Reply #19 on: July 29, 2009, 03:55:53 PM »

Good update, Clark. Did similar things to my big transmitter years back. Ditched the clipper, swapped out the grid resistor (1M IIRC) for a 4.7M, huge improvement. Later I fattened up the coupling caps from .01s to .1s and beefed up the eletrolytics a bit. Seems fairly universal on these old rigs.

My memory of past GK discussions is mention an audio amp/driver weakness that can be overcome exactly as you've done. Looks like you found your way there handily.

Wouldn't mind picking up a GK to play with one day. Always liked the looks of 'em.
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ke7trp
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« Reply #20 on: July 29, 2009, 04:28:48 PM »

All that is done..  Smiley   With outboard audio I have it sounding fantastic. With the D104 it sounds nice and smooth. This element has alot of mid and not much highs.. But I kinda like the sound.

GKs are nice if you always wanted a GK. As long as you can accept the fact that it has low B+ on the 400, and the mod deck needs alot of work.

Clark
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« Reply #21 on: July 29, 2009, 08:29:45 PM »

Clark...did you ever find a solution to your banging meter movement on the mod deck?  Did you change it to read plate current or maybe dampen the movement with a little capacitance?

Frank
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ke7trp
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« Reply #22 on: July 29, 2009, 08:32:12 PM »

I put a cap across it but it did not seem to work.  Its a real problem. I have backed my audio down to 100% mod so I dont slam it but on peaks it will still hit all the way over. The Meter is acurate.. I tested the Idle current on the 811s.. Got a suggestion?

C
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« Reply #23 on: July 29, 2009, 08:52:05 PM »

Did you try maybe 1000uF and adjust up or down from there?

Frank
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ke7trp
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« Reply #24 on: July 29, 2009, 08:56:43 PM »

No.. No 1000F... I tried a 10, 20 and I think a 100.  I was unsure of the voltage and just clipped it on there.I would like the static current to stay the same so I can watch that..Or maybe just cut the reading in half would be cool!

Clark
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