Viking 2 CDC capacitor wiring

[N9axl]

I'm getting ready to replace these electrolytics.  The first one 15/15 450 is connected across v10.  This is on the left. Green and red positive wires to v10 pins 3 and 8 and common negative to 6AL5


The second 15/15 150   This is on the right. The two positive wires seem to run under the relay. And the negativewire to a terminal strip on the right side of the relay.a second negative to the 6al5

I've checked the schematic several times and this appears to be correct.  Before I solder this all together would someone be willing to confirm my thinking here. Johnson isn't always consistent between schematic and reality.

The photo by the way doesn't do justice to the fine capacitors which I had Chuck Hurley run up for me.  These are lovely, highly professionally made, and well labeled with long leads.

[kd1nw]

Hi,

I don't have the CDC but it looks basically the same as a regular V2. Grab the assembly manual for the regular V2 and check step 41 and 42 on page 28. The original 450V tubular was a 3 wire cap, 2 pos and one common neg wire.  I replaced mine with 2 axial caps exactly as the original was installed. Positive end of one cap to pin 8, positive end of other cap to pin 3 of 5V4 X10. The negative ends both went to the terminal strip X22. The 150V cap (C12 - 13) was a four wire cap. Positive wires were connected to a ground lug close to R13, negative wires of the cap to pins 6 and 7 of the 6AL5 X11. I used a couple of radial caps for these and used the ground lug at the 6AL5 instead of going half way across the radio.

Your 450V sounds like it could be okay if you are putting your common ground connection at the 6AL5 to a ground tab or ground tie point? Your description of the 150V doesn't sound right to me. You might want to review your wiring against a CDC construction manual if you can get one. Also, I'm certainly no expert, so you might want to get a few more opinions on it too. 

Good Luck and 73
Kevin KD1NW

[kb2vxa]

+1, your description doesn't match the schematic unless the 6AL5 pin is grounded. Go with the schematic, it is correct. For what it's worthless, I'd go with 20uF caps, a little more filtering wouldn't hurt. IMO the V2 is the best AM transmitter Johnson made, it lends itself nicely to audio mods and of course external peak limiting like an Orban AM Optimod for the "professional" ham (;->) is pretty much essential if you don't want that piss weak hyellowy audio. Oh and of course it has plenty of knobs I like to play with.

[N9axl]

Thanks. The assembly manual on Bama has no pictures or figures.  Is the x22 terminal strip the one to the right of the relay underneath the length of coax?

[KB2WIG]

.

[N9axl]

Here's the picture. The 150 v on the right - positive red and green, one negative to the terminal strip (x22?) on the right, the other negative going to the 6AL5.  The cap on the right is the 450 v with two positives and a common negative going to v10 and the 6AL5.

[kd1nw]

Hi,

Is that the way it was originally wired? Because it sounds wrong. None of my wires for the 450V go to the 6AL5 and none of my wires for the 150V go to X22. Your 450V cap should only be associated only with connecting to X10 and X22. Positive terminals to 5V4G (X10) and any negative terminals to X22. Your 150V cap should only be associated with the 6AL5 (X11). This is 'reverse' connected. Positive wires to ground and negative wires to the 6AL5 pins. Your description has wires from your 150V cap going to X22 which is not right, in addition you have your negative wires of your 150V going to ground which is not right, the cap will be damaged. At great personal risk, I've attached a couple of pics of my shoddy workmanship . But I hope it can help you see how it's laid out. One is a pic of the whole underside with some annotations so you can see where things are in relation to each other. The other is zoomed in a little more on the 6AL5 caps. My radio is not the CDC version, so I don't have the relay.

Thanks 73
Kevin - KD1NW

[kb2vxa]

I posted yesterday but apparently it didn't "take" so here is the essential again. The schematic is correct, it's your description that isn't, or somebody wired it incorrectly with the grounds in the wrong place. Instead of what are grounded tube socket terminals they should go to ground lugs on the nearest terminal strip(s). BTW, a little more capacitance for better filtering wouldn't hurt, say about 20uF.

[N9axl]

Thanks. It was backwards. As it now sits the 150 volt has negative across the 6al5 pins 2 and 7 - it's hard for me to count the number - and  positive to ground - the red and green wires going up under the relay. The 450 has negative at x22 fourth terminal going from the back of the chassis and positive at v10 at pins 3 and 8 counting clockwise from left. The appears now, finally, to be right.

The lesson here: assume whoever last worked on this radio, me last week or Susie Assembler in 1955, did it wrong!!!!



My workmanship is equally shoddy. 

[kd1nw]

It sounds right to me now, unless anyone disagrees.

To count your pins, on the 5V4, the base is keyed with a notch. With the tube plugged in you can see the notch from the ceramic socket where you do all your soldering. Count going clockwise from the notch. Actually on mine the numbers are right there on the ceramic bases.

The 6AL5 is a little trickier, it's keyed by a wider spacing between pins 1 and 7 which is sometimes hard to see. Start with the rightside pin on the widely spaced pins and count going clockwise. You can pull the 6AL5 too and should be able to see the widely spaced pins a lot easier. You can also verify it by using the schematic and the tube socket connection diagrams in the manual. It doesn't hurt to do both.

And no worries on the workmanship. My takes is that if it's functional and safe then fine. I can always go back and redo it when my skills improve or the next person that gets it can do it to their liking. I hope you don't need anymore photos, I'm going to button it back up and that's a bunch of screws on the bottom plate     

Also, a couple of tips I've learned the hard way, take lots of photos before doing any work so you know how it was hooked up originally. And only work on one or two component leads at a time so you don't lose track of your connections. Be safe and have fun.

Good luck and 73
Kevin - KD1NW 

[N9axl]

Thanks much. This is done underneath. At this point what's left is to put on a new power cord, check the replaced caps, put the oil filled cap back in and button up the bottom.

need to restring on top. how hard is it to,remove the face plate?

I need to find the #40 bulb for the filament light, two feet, and various tubes. Off to Fleabay I go.

[k7mdo]

Here is a new "gotcha" on the cdc Vikings.... if you are leaving in the selenium rectifier be aware that it's clearance to the bottom cover of the transmitter is very minimal....  the fins are at B plus and if you are not careful they can contact the transmitter bottom cover thus shorting HV to ground.... 

The selenium can accidentally get rotated and come way too close to the cover.

73, Tom

[kb2vxa]

In close clearance situations a piece of black vinyl electrical tape on the cover put the Alfred E. Neuman to it for me. BTW I hate solemnium rectumfriers that have a bad habit of going open and replace them with sillycone dymodes. That's a common problem with the R-390 receiver, then some of the T-R protection relays don't work leading to a possible uh oh.

[N9axl]

I have already replaced the selenium rectifier with a resistor diode combo.

[N9axl]

This all worked.  I finished checking the caps and then installed a grounded power cord. With just the LV rectifier installed - we have filament voltage and everything came on without drama.

 Good progress.  I now need to get the HV rectifier tubes and the 6146 tubes installed.  Fortunately this came with the 807s left in it so that's one less thing to locate. I also need to find two feet and the filament light bulb.

Before I do that I plan to build a chicken stick so I can ground the caps etc once the high voltage comes into play.

[kd1nw]

Great, thanks for the update. I'm glad to hear things are coming along

[N9axl]

Thanks. I have all the tubes either here or on order. Only 1 6146 available so I need to get that. They won't be matched.  I may have a 6146b somewhere but I dislike mixing tubes.



. And as a hint and tip - I went to Lowes looking for a short piece of PVC tubing. No good since 5 feet seems the minimum.  I then saw the lawn irrigation section.  They sell a one foot piece of pipe threaded.  There is also a separate valve that threads on. All for $2.  I popped out the center of this valve and it took the small eyebolt I had perfectly.  Soldered on an insulated wire and good to go.

Now if only the audio on my SBE 34 was as good to go.  No audio output. Assume the PNP audio output transistor that drives the speaker has failed.  I have a spare but it's just one more project.  Just a scratchy noise when I turn the volume and no sound when hooking up external speaker.  

[Pete, WA2CWA]

Thanks. I have all the tubes either here or on order. Only 1 6146 available so I need to get that. They won't be matched.  I may have a 6146b somewhere but I dislike mixing tubes.

6146's in parallel don't have to be matched.

Now if only the audio on my SBE 34 was as good to go.  No audio output. Assume the PNP audio output transistor that drives the speaker has failed.  I have a spare but it's just one more project.  Just a scratchy noise when I turn the volume and no sound when hooking up external speaker.  

Hang a scope lead on the center wiper of the volume control to see if you have audio wiggle. Then, working towards the speaker, test each stage for audio output.

[N9axl]

Now, I did actually fire up the CDC.  The filaments lit up but I saw nothing on plate voltage or anything else. Also no drama with blown fuses, sparks, etc - always a good thing. 

This was done with only one HV rectifer tube installed since I am waiting on the other.  A really dumb question, but would having only one account for no oscillator current, etc?  I'm still not sure about how to set this up. I put a 7.103 Crystal in position 1 and tried to set it up with the charts in the manual, but not sure I have those right.  My manual is fuzzy Repro. I made sure a key was in the jack.

My plan here is to use this solely on 40 meters as that is all I have antennas for.



I have no scope. I need one - or actually I should fix the Heathkit scope I have in the corner.   I plan to check the voltages across the audio  -- I have the maintenance manual so I know what they should be. I'm thinking if the audio output transistor to the speaker is blown that's the issue.  

[w1vtp]

Now, I did actually fire up the CDC.  The filaments lit up but I saw nothing on plate voltage or anything else. Also no drama with blown fuses, sparks, etc - always a good thing. 

This was done with only one HV rectifer tube installed since I am waiting on the other.  A really dumb question, but would having only one account for no oscillator current, etc?  I'm still not sure about how to set this up. I put a 7.103 Crystal in position 1 and tried to set it up with the charts in the manual, but not sure I have those right.  My manual is fuzzy Repro. I made sure a key was in the jack.

My plan here is to use this solely on 40 meters as that is all I have antennas for.



I have no scope. I need one - or actually I should fix the Heathkit scope I have in the corner.   I plan to check the voltages across the audio  -- I have the maintenance manual so I know what they should be. I'm thinking if the audio output transistor to the speaker is blown that's the issue.  

You can get some really professionally created manuals from several sources.  It would be worth the minimal expense.

[N9axl]

I plan to do that. I need to clarify the issue of the octal socket X12 in the back.  In my Ranger this is essential for the radio to function that this plug be there. The manuals I have say nothing about this.

[KB2WIG]

K,

Look at this attachment. It shows which rectifiers power which ckts.

I solid stated the HV with a bunch of 1N4008s. I also added an inline fuse for the low voltage transformer. Replacement of the transformer would be expensive.

klc

[N9axl]

Today i fired this up and see get no oscillation current, no buffer, no voltage between pin 3 and ground on the VFO plug. A low b+ issue since there should be 300 volts. Now on the 5v4 there was 380 volts between pin 3 and ground so t2 is working.

In earlier discussion pin3 was seem as correct.

However,the pin out diagram for the 5v4 shows the plate is on pin 4 not 3. It would seem that pin 4 is the correct tie point for the positive of the 450 volt cap. Pin 3 is not used in a 5v4.

Am I thinking about this correctly?

[w8khk]

I looked at the Viking II schematic in the manual.  It does not have pin numbers on the tubes, so it would be  necessary to use a tube manual to determine the correct pins if you are not familiar with each of the tubes.

The 5V4 low voltage rectifier has two plate pins, 4, and 6.  One of each of these pins should connect to each end of the high voltage winding of the low voltage power transformer.  There should be NO other connections to these pins.   

The filament and cathode of the 5V4 uses pins 2 and 8.  These go to the five volt winding of the same transformer.  One of these pins connects to the low voltage filter choke.  That is the pin where the positive lead of the 450 volt electrolytic capacitor should be connected.  The negative lead of this capacitor goes to ground.  The assembly manual may clearly reveal which of pins 2 or 8 is used for this connection, but it really does not matter, as long as the choke and filter capacitor are connected to the same pin.

There are no connections in the 5V4 tube to pins 1, 3, 5, and 7.  If any wires are connected to these pins, they are just being used as tie points for other parts of the circuit.  A check of the assembly manual would reveal whether the connection you see is stock or a modification.  The CDC version power supply is likely very similar to the more common Viking II.

The Viking II manual is available on the BAMA site or the Edebris mirror site.

[N9axl]

The wiring seems right. I am wondering if I misunderstand how to tune this. I have a 7.200 crystal in position 1. This isn't tuning on 40 but on a different band using that crystal. I need to figure out the proper settings and what band a 40 meter crystal would be used for.