The AM Forum
March 28, 2024, 08:13:10 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1] 2   Go Down
  Print  
Author Topic: Project VIking II, another brother, but BETTER !  (Read 31370 times)
0 Members and 1 Guest are viewing this topic.
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« on: August 08, 2013, 11:16:54 PM »

Well figured it was time to start this behemoths own thread, Ive been rambling on other threads but the time has come ! Arrived via Fed-to-the-X today !

Stripping her down for cleaning and repair tonight ! Yes yes..... IT is ON !

Ok, turning down the volumn level no more exclamation marks. Front main dial coupling.....mangled and covered in a gob of silicon. I am a far better mechanic than electrical fiddle-farter so Ill takle that first after clean up.

I have notice a lot of out of place and new/oddball parts underneath the chassis. My first Viking, and I have yet to start tracing wiring, but there seems to be two added relays. PTT Huh? anything else you guys see out of place or worth noting please speak up, ha.





Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #1 on: August 09, 2013, 04:47:43 PM »

Fixed the coupling with two cotter pins, works great and has no rotational play. re-assembled and ran up on a variac with no 5R4 tubes installed. All seemed well ramping it up slowly, then.... I noticed the cherry red 6AL5. Flipping the anvil over, it appears these 15mf 450V caps might be a little dry...ha. Someone was definitely on a budget when the were messing with this thing.

So, the 6AL5 tube, got awefully red ! No fireworks though, just a really hot hot toooob.


Cleaned up the rig.


Rebel caps in view.


Dryer than a popcorn fart.
Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
Jim, W5JO
Member

Offline Offline

Posts: 2506


« Reply #2 on: August 09, 2013, 04:59:26 PM »

I would invest in some electrolytic caps before the AC plug see a socket again.
Logged
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #3 on: August 09, 2013, 05:25:44 PM »

Knee deep in that as I type.

While replacing the 15mf's I keep staring at this rectifier setup..and it doesn't make since to me. The diods are on pins 1&5 (  http://www.r-type.org/pdfs/6al5.pdf ) makes sense up to that point to me. Wonder why this thing came with a 6AL5 if it looks like they by-passed it with the diodes, I keep looking at the circuit and one other thing that's got me scratching my head is the have another OLD paper cap (3 way 30/30/20 all pos tied together) tagged on at the -75 output line....that then goes to some honkin relay... can someone explain what the heck Im looking at ?



Edit: yep PTT mod.
Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #4 on: August 09, 2013, 06:55:17 PM »

Alrighty, replaced the caps on the 6al5 circuit.....but that guy is still taking off ! Its fine for about 30 seconds of filament....then she suddenly turns cherry. Don't know how many more of these guys Ive got in the junk box. What could be causing that ? Oscillation ? Any ideas ?



Ya know, I told myself...I needed to get in here  and start communicating with you guys. I said, heck...I bet I can learn a lot ! Figured I would start a little thread or two to get some conversation started, all of them are basically dead air.... Is this the comraderie I hear about ? Dang, maybe this wasn't the start of a neat venture that Id thought it would be. Ill carry on as I always have with some neat projects....But if it hasn't felt like pulling teeth trying to get some kind of conversation going on around here.


Im either too young or too stupid for this place it seems...

Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
Jim, W5JO
Member

Offline Offline

Posts: 2506


« Reply #5 on: August 09, 2013, 08:15:19 PM »


Im either too young or too stupid for this place it seems...

 

Don't worry, it is summer and participation is always low.  If you have red plates then either the tube is bad or something is drawing a lot of current.  Disconnect the output wire from the tube and see what it does.  Did you put the capacitors in correctly?  This is the bias rectifier so the filters should have the positive to ground.  Any shorts near the tube socket.  Is L3 shorted in some fashion?

What condition is R15, 16 & 17?   Remove the lead at the connection of C 12 and R17 that goes to the rest of the transmitter after you check the proper installation of the filters and the all the other parts and try again.  You can use an ohm meter to look for lower than normal resistances but if you don't have experience in that method, I don't suggest you do that just yet.

If, by chance, you put the filters in wrong polarity then don't just reverse them, replace them they are bad.
Logged
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #6 on: August 09, 2013, 08:39:48 PM »

Thanks Jim for the words of encouragement.

Yes, that is exactly what I did. Found that about 30 minutes ago. Since the start of the day, Ive ripped out the PTT additions, replaced caps and am now actually loading it up. Im just past the point of throwing the plate switch, and all is well there. I slightly loaded it to about 10 watts and halted to grab a beer and wipe the sweat off my forehead. By the book, all readings and adjustments are working as should. I will need to cross one more bridge shortly, and that is the missing tube that belongs in an added socket in the speech amp stages. 

Thanks again for the advice Jim, that is exactly what it was.
Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
KB2WIG
Contributing
Member
*
Offline Offline

Posts: 4484



« Reply #7 on: August 09, 2013, 09:10:11 PM »

Grab some 1n4007 1A/1000V diodes from Mouser... $4.00 for 100. I generally use 1N5408 as they are rated for 3 Amps at 1KV.  $9.60 for 100.

http://www.mouser.com/

Looks like someone has been playing around the 6AL5

klc
Logged

What? Me worry?
WBear2GCR
Member

Offline Offline

Posts: 4135


Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #8 on: August 09, 2013, 09:30:48 PM »


Don't forget the infamous "chernobyl" resistor in the VFO.

I'd have kept the PTT stuff, unless it was very funky.

there needs to be negative bias on the 6AL5, check tube manual for values.
No negative bias, tube gets cherry red.
Check the cap that goes TO the grid, and the voltage on the grid wrt the cathode.

Logged

_-_- bear WB2GCR                   http://www.bearlabs.com
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #9 on: August 09, 2013, 09:42:49 PM »

The magic smoke has left the building.

Some of it at least. All was going pretty good, just finished finding my first dip in the main dial when I turned to read the next step....a familiar smell wafted over to my nose. Appears the HV transformer has layed down on my, I shut it down fast but too late I fear. I pulled the 5R4's and lit it back up and carefully watched after applying the plate, and after about 15-20 seconds a whift of smoke again. Ive buttoned it back up for tonight, and will search for a replacement as soon as I get the wind back in my sails.

Im picking up a Ranger tomarrow, so my attention will be diverted and a better mood will ensue shortly after Im sure.

The bias caps were installed polarity backwards and all turned well with the 6AL5 tube.



Shut down shop, time for a cold refreshment and a Fender in my lap. Thanks again, I was wondering if I was here all alone for a while.
Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
Jim, W5JO
Member

Offline Offline

Posts: 2506


« Reply #10 on: August 10, 2013, 07:19:24 AM »

You are never alone,  It is just sometimes life gets in the way for all of us.  Sorry about the transformer.  If nothing surfaces you can have it rewound. it isn't cheap but is a solution. 

Be careful on the Ranger.  If it has not been serviced in a while, you will have the same set of circumstances.  Remember the polarity as you do the replacements.  One way is do them one at a time so you have something to compare, or use a digital camera to preserve the layout so you can look as you put it back together.  When you get to the audio circuits, pay partucilar attention to the layout because if you don't, you could build in problems as you go.  Have fun and keep plenty of beer available.
Logged
VE3AJM
Member

Offline Offline

Posts: 378



« Reply #11 on: August 10, 2013, 10:30:28 AM »

 Have fun and keep plenty of beer available.

I would advise to keep the beer or any talk of it to a minimum when working on or pondering repair work with any of these vintage transmitters, especially for the first time. That's up to you of course.

HV can be deadly. There is a time and place for everything.

Al VE3AJM
Logged
W6MQI
Member

Offline Offline

Posts: 65


« Reply #12 on: August 10, 2013, 10:50:42 AM »

The magic smoke has left the building.

Some of it at least. All was going pretty good, just finished finding my first dip in the main dial when I turned to read the next step....a familiar smell wafted over to my nose. Appears the HV transformer has layed down on my, I shut it down fast but too late I fear. I pulled the 5R4's and lit it back up and carefully watched after applying the plate, and after about 15-20 seconds a whift of smoke again. Ive buttoned it back up for tonight, and will search for a replacement as soon as I get the wind back in my sails.

Im picking up a Ranger tomarrow, so my attention will be diverted and a better mood will ensue shortly after Im sure.




The bias caps were installed polarity backwards and all turned well with the 6AL5 tube.



Shut down shop, time for a cold refreshment and a Fender in my lap. Thanks again, I was wondering if I was here all alone for a while.



  Get a hold of BRY, AF4K http://af4k.com/JOHNSON_VIKING_II_PARTS.htm he may have what your looking for. I too almost burned out T2 until I found a short in the PTT circuit someone installed needless to say I got rid of the PTT mess besides why do I need PTT? I'm still trying to find out why my unit will allow tune up in phone but, when switched to CW I get high plate current with no way to dip the plate it stuck at 230 ma.

73,Dave
Logged
Jim, W5JO
Member

Offline Offline

Posts: 2506


« Reply #13 on: August 10, 2013, 11:37:00 AM »

 Have fun and keep plenty of beer available.

I would advise to keep the beer or any talk of it to a minimum when working on or pondering repair work with any of these vintage transmitters, especially for the first time. That's up to you of course.

HV can be deadly. There is a time and place for everything.

Al VE3AJM

Now Al, all that depends on when the beer is consumed, doesn't it?  No one advocates consuming any alcohol when doing the work.  By the way, I have seen people burned terribly from 48 volts or less with high current,  If we want to get into a safety discussion then he best remove all jewlery and metal objects from his person as well.
Logged
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #14 on: August 11, 2013, 04:57:33 AM »

Got the Ranger today, really am pleased with it. Worked this evening replacing the last three old caps and throwing a antenna changeover together.

Hoping to dig back into the Vikingthis evening. I might have a transformer around here that will work, sure don't have 160 for a re-wind although that IS a good price.
Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
WD5JKO
Member

Offline Offline

Posts: 1996


WD5JKO


« Reply #15 on: August 11, 2013, 09:17:13 AM »

I might have a transformer around here that will work, sure don't have 160 for a re-wind although that IS a good price.

    If your open to changing the original EF Johnson circuit design, consider replacing that transformer with a control transformer. Look for a 120V in with two secondary windings for either 240V (parallel) or 480V (series) connections. About a 350VA unit should do. Just go to Ebay and search for "Control Transformer 350VA", and several pop up..I see one for $8.00 used. Perhaps a 250VA unit would do.

   The idea would be to configure transformer as 120V in and 240V out, and use a full wave voltage doubler circuit with two diodes and two caps. The caps could each be something like 330uf @ 400V, and each diode a 1N5408. This will make just  under 600V DC at 500ma load.

   The idea would eliminate that HV oil capacitor, and the HV filter choke. The high capacitance would best be dealt with using a step-start relay with PTT B+ control.

  I attach a simulation from the Duncan PSU Designer II Cad program.

Jim
WD5JKO


* FW_Doubler.png (30.84 KB, 1248x507 - viewed 510 times.)
Logged
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #16 on: August 12, 2013, 03:33:28 AM »

Great tip !

Thanks, I hadn't thought one iota about that doubler idea. Ya know now that you mention it, Ive got a control transformer that may work in the garage.

Heres the specs...
http://livewiresupply.com/electrical-transformers/dongan-electric/50-0200-056.html

"POWER TRANSFORMER, CONTROL; POWER RATING 200 VA; PRIMARY VOLTAGE 600/575/550 VAC; SECONDARY VOLTAGE 120/115/110 VAC; 1 PHASE; 50/60 HZ; TEMPERATURE RISE 55 DEG C; UL, CSA"




That will put me slightly over 660VDC though...I think the formula is X 1.14 VAC for rectified cap filter PS right ? Anyone ever use a dropping resistor on a primary with success ?
Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5055


« Reply #17 on: August 12, 2013, 07:12:35 AM »

Alrighty, replaced the caps on the 6al5 circuit.....but that guy is still taking off ! Its fine for about 30 seconds of filament....then she suddenly turns cherry. Don't know how many more of these guys Ive got in the junk box. What could be causing that ? Oscillation ? Any ideas ?



Ya know, I told myself...I needed to get in here  and start communicating with you guys. I said, heck...I bet I can learn a lot ! Figured I would start a little thread or two to get some conversation started, all of them are basically dead air.... Is this the comraderie I hear about ? Dang, maybe this wasn't the start of a neat venture that Id thought it would be. Ill carry on as I always have with some neat projects....But if it hasn't felt like pulling teeth trying to get some kind of conversation going on around here.


Im either too young or too stupid for this place it seems...


No not quite dead air,,,,,,BUT do you have a schematic of this transmitter? Pictures of the underside and telling us about a glowing 6AL5 doesn't spark a reply and someone says , "Oh! the trouble is this or that". One member here might say that "Hammy Hambone" has been in it and it needs close inspection before plugging it in again. It sounds like that beast you bought from somewhere needs to be looked at carefully using the schematic to get it to working order. It looks like it had a very rough life, by someone who hasn't a clue about electronics. The transformer can be damaged by the bad overloads it is seeing now.
Someone replied to replace all electrolytic caps...And make sure the new ones are installed properly. Mouser or DigiKey are good places to by electrolytics.
Fred
Logged

Fred KC4MOP
WD5JKO
Member

Offline Offline

Posts: 1996


WD5JKO


« Reply #18 on: August 12, 2013, 07:46:02 AM »

"POWER TRANSFORMER, CONTROL; POWER RATING 200 VA; PRIMARY VOLTAGE 600/575/550 VAC; SECONDARY VOLTAGE 120/115/110 VAC; 1 PHASE; 50/60 HZ; TEMPERATURE RISE 55 DEG C; UL, CSA"

That will put me slightly over 660VDC though...I think the formula is X 1.14 VAC for rectified cap filter PS right ? Anyone ever use a dropping resistor on a primary with success ?

It should work so long as you don't run a tone at 100% modulation too long. The lower VA rating will cause the B+ to droop more, and I'd bet the B+ would be around 700V key down which is fine using the 575V HV tap on transformer. This control transformer needs a bridge rectifier (not a doubler), and the caps need to be in series across the B+ and use equalizing resistors. You will want a lot of capacitance; like 330uf @ 450V X2...and a step-start relay.

Jim
WD5JKO
Logged
VE3AJM
Member

Offline Offline

Posts: 378



« Reply #19 on: August 12, 2013, 09:35:18 AM »

You will need a replacement plate transformer yes, but have you actually resolved why the original plate transformer smoked/opened/shorted? Was it just the transformer giving up the ghost on its own or another component in the HV line that has failed?

From what you've written on here and other threads, apparently there was no fusing/wrong value fuse there. So a transformer winding was acting as a fuse, which is never a good thing.

Al VE3AJM

Logged
KB2WIG
Contributing
Member
*
Offline Offline

Posts: 4484



« Reply #20 on: August 12, 2013, 10:09:17 AM »

I've found the following to be usefull when working with older equiptment.

http://amfone.net/Amforum/index.php?action=gallery;su=user;cat=53;u=714

Its really good for initial power up; the lamp limits the current, or becomes a fuse if there's a short somewhere. The switch is wired so that when thrown, it shorts out the bulb which will apply full voltage to the unit under test. You can even put a real screw in fuse to get higher values of pro tection.


klc
Logged

What? Me worry?
KI4THX
El' Guappo Ernesto
Member

Offline Offline

Posts: 57


It's 106 Miles To Chicago, We Got A Full Tank Of G


« Reply #21 on: August 12, 2013, 10:18:26 AM »

Yes, no fusing on the Hv x-frmr. I hate to admit this in the open airwaves, but I dont think I let it dry completely after its waterhose bath....think I still had some moisture in the HV iron. Been washing old nasty equipment like that this way for 20 years and this is the first catastrophe I can accredit to my scrub job.

Just got too excited I guess.

Ill strive to be calmn from here on out, ha ha.

Logged

It's 106 Miles To Chicago, We Got A Full Tank Of Gas, Half A Pack Of Cigarettes, It's Dark And We're Wearing Sunglasses.

HIT IT !
N0WEK
Contributing
Member
*
Offline Offline

Posts: 790



« Reply #22 on: August 12, 2013, 11:25:08 AM »

I've found the following to be usefull when working with older equiptment.

http://amfone.net/Amforum/index.php?action=gallery;su=user;cat=53;u=714

Its really good for initial power up; the lamp limits the current, or becomes a fuse if there's a short somewhere. The switch is wired so that when thrown, it shorts out the bulb which will apply full voltage to the unit under test. You can even put a real screw in fuse to get higher values of pro tection.


klc

That's a great old radio guy trick that I've been using for years. Many people have used this for warming up and reforming caps in older radios and it works pretty well, but of course the tube rectifiers don't start to conduct until the filaments get to a certain (unknown) temperature. I'm not big on trying to reform old caps since their later failure frequently takes something else with it.

I start with a small bulb, 15 or 25 watts and let things warm up for a day or so just to warm up and dry things out and then work my way up until I get to 100 watts.

In some ways it's better than a variac, since it's got built in current limiting. I suppose the best version would have both a variac and a bulb. I keep a voltmeter across the equipment side just to see what it's doing.
Logged

Diesel boats and tube gear forever!
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5055


« Reply #23 on: August 12, 2013, 08:09:03 PM »

Yes, no fusing on the Hv x-frmr. I hate to admit this in the open airwaves, but I dont think I let it dry completely after its waterhose bath....think I still had some moisture in the HV iron. Been washing old nasty equipment like that this way for 20 years and this is the first catastrophe I can accredit to my scrub job.

Just got too excited I guess.

Ill strive to be calmn from here on out, ha ha.


Well you gave it your best shot. This summer has not been hot enough to dry electronics. That piece could fit in an oven set for lowest temperature and left in there for four hours. Fusing these old soldiers is very critical.
Fred
Logged

Fred KC4MOP
Jim, W5JO
Member

Offline Offline

Posts: 2506


« Reply #24 on: August 12, 2013, 08:19:21 PM »

What happened to you is not all that uncommon so don't fret.  Given the incident you would probably have had to fuse each winding, which is impractical.  The lesson here is be careful when replacing components, in this case one at a time so you would have a comparison.

Aha the price of experience, but don't let anyone discourage you.
Logged
Pages: [1] 2   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.07 seconds with 18 queries.