Johnson Viking II Restoration

Discussion in 'Technical' started by K8CCA, Mar 5, 2016.

  1. K8CCA

    K8CCA Member

    Hello to the Forum, this is my first posting here. I am new to AM, but have messed around with vintage rigs for many years. I seem to prefer to buy everything broken. I enjoy fixing the old rigs.

    I have been wanting to get on AM with vintage gear for a while. Last year I restored a HQ-180 that came out quite nicely, and I have been looking for a proper vintage transmitter for a while. I found a Johnson Viking 2 and figured why not. I brought it home and of course tore it apart to start on the restore. I found that the filament wiring had burned down and went to work re-wiring the old girl. I have replaced the wiring, wax paper capacitors, and the electrolytic capacitors. I also cleaned the old girl up and found a few mistakes in the original build. 4 joints had never been soldered! After I get the transmitter put back together, I will start on the Johnson VFO 122 and then onto the air.

    Here are the photos, enjoy!

    Here is the front panel before cleaning


    Here is some of the burned up wiring

    20160227_165421.jpg~original.jpeg 20160227_165438.jpg~original.jpeg 20160227_170335.jpg~original.jpeg 20160227_170423.jpg~original.jpeg
  2. W5HRO

    W5HRO Administrator

    Does the filament winding in the power transformer still work? I wonder if it was damaged or not?

    Someone must have had a tube filament short, a .005uF cap or the green wire was shorted to one those mounting screws. Maybe the edge of one of the nuts went through the green insulation and shorted it.
  3. W6MQI

    W6MQI Member

    Nice Viking II once you solve that possible shorted filament line issue, and hopefully that's all that's wrong you will enjoy using the V2. I gave up on using a Johnson 122 VFO tried all the tricks to stabilize it some worked some didn't do JACK ended up with a DDS and never looked back. One thing on my list of to do's would be to find someone to repaint the case, and front panel so far no luck wrote one guy back east can't remember his call never did get a response.


    What's in the key jack sorta looks like a push switch?

    73, Dave
  4. W5HRO

    W5HRO Administrator

    That guy posted this exact same thread on qrz on the same night shortly before he came here and did it. He did a copy there and a paste here. I think he didn't like that fact the img tag is disabled here and he kept trying to post and thought I or the board was somehow against him. Seriously, that's what happened and he never came back. He made 3 posts trying to link the photos and couldn't figure out what was happening and said he must not be welcome here ::)

    The img tag is disabled here because how many times have you read through an old post on the web only to find the linked photos were no longer there when you clicked on them? Most forum sites including qrz have data size or storage limitations so they would rather you do that, but we don't have that limitation here and have unlimited storage space. The img tag is disabled to force people to upload the photos to preserve that data.

    Anyway, I still have my Viking II which is super modified, but I never did finish the last step on it. Since 10-meters is about gone again I would rather just finish up the big rig and use it on the low bands instead. I may wind up using the V2’s tuned output network anyway when I go the build driver for the 4-1000A amp after.

    What's funny is before the Internet Viking II's were very hard to find. I remember guys always searching around for them, but they could never find one. Now they are all over the place.
  5. W6MQI

    W6MQI Member

    I purchased mine from a local ham here in KLVK for $10.00 he originally wanted a dollar a pound, I took a ten out of my wallet and he quickly said SOLD! he even carried it to my truck now that's service hihi. This guy couldn't wait to remove this hulk from his garage he even tried to give me a Zenith TransOceanic receiver I scratched my chin for a couple of seconds thinking then passed I didn't need anymore junk at QTH.

    So what all did you do to it?
  6. W5HRO

    W5HRO Administrator

    Johnson Viking II Modification Project

    The only thing is the -80V 6146 control grid bias circuit is not 100% and I needed to change it. What I have shown in that drawing needed to be modified with a grid leak resistor instead.

    EDIT: I looked at that drawing again and it looks like I did add the 13.5K grid leak resistor for the 6146's, but only on the drawing. I just never added it to the transmitter itself because I have not been using it.
  7. W6MQI

    W6MQI Member

    Mine had a funky PTT setup which I removed other then that it's bone stock. I see your NC-303 on its side I've been sorta of thinking of selling my 303.
    Starting to get into a slump with ham radio maybe its the weather starting to turn nice who can say.
  8. W5HRO

    W5HRO Administrator

    I looked around and I no longer have the pics, but I removed that big 8uF oil filled cap in mine and mounted an orange 20A solid-state relay with some heat-sink grease on the side of the chassis where it was because it's right there where the transformer is and it's primary wires are. Of course I also had to change out the mic jack to a 1/4" 3-conductor jack (tip & ring + the key) to make it have PTT and switch the relay.
    That's my other NC-303.

    I would hang on to it, especially after all the work you did to it. Next winter you'll wish you had it again. Just start tuning it to around the high end of 40-meters. A lot of the guys (AM’ers) are around 7290 and 7295 every night now. There were several California stations on just last night. I think it’s because 75-meters is shutting down so they are moving up to 40 instead. I’ve been posting reports down in the 40-meter band forum. I just didn’t do it last night.
  9. W6MQI

    W6MQI Member

    Yea a friend of mine said pack it up real good, and store it some where in the garage along with the Valiant, that way its not in the way in shack to piss me off when I bang my knee against one of them. The Valiant is on a bottom roll out shelf next to the operating position so far I've succeed in banging my knee on the VFO knob several times OUCH! not me the Valiant. If I break that bakelite shaft couplling lets just say I'll be more then mildly pissed off. Been talking about enlarging the shack with the xyl , but neither of us really want to spend the cash right now putting the backyard back together is our priority.
  10. W1VTP

    W1VTP Member

    If you do that be sure to put it into a sealed plastic bag with a 16 oz packet of desiccant. That's how all these old BA's get all rusty and crusty

  11. W6MQI

    W6MQI Member

    Good idea just need to remember to pull the desiccant bag out every six months or so and recharge it by drying it out in the oven.

    73, Dave
  12. W6MQI

    W6MQI Member

  13. W5HRO

    W5HRO Administrator

    Look at when that topic first started, back on Feb 23. The guy didn't start it here until March. It was also started on QRZ. Guess he wanted to cover all of the bases. It's all show and tell now.

    It's kinda like that one new AM node they started on QRZ. Just all old news show and tell type topics with no real substance. Just another dog and pony show. Sort of the same thing they have done to Electric Radio Magazine.
  14. K8CCA

    K8CCA Member

    Hey guys, lost track of this site and posting. Got the Viking up and going. I rewired the filament circuit, but was still having issues. I pulled a dumb error and wired the bias supply caps in backwards. I did negs to ground not thinking it thru that the - 75 needed POS to ground. After I got that figured out, I found that R13 was open on one side. Got a replacement from mouser and she worked good for a little while, then something happened to the vfo. It works fine on crystal but I only have 1 and it's at 7.159. I started building a dds vfo, but have not got it done yet.
    Sorry if I ruffled everyone up. Was trying to figure it out at the time and had the self imposed bias issue and got frustrated with the site. Was hoping for help, but I got it figured out.

    I have now picked up another one, which I also got going, but again on 7.159.

    Need to find some time to finish the vfo.
  15. W5HRO

    W5HRO Administrator

    The VFO is a simple thing and has very few components. What exacty is it not doing?

    Did you check R51, the 18K 2W screen dropping resistor inside of it?
  16. W6MQI

    W6MQI Member

    I fought with my Johnson VFO as well never could get it real stable at least for CW work for AM op's it was fine though. I currently use a N3ZI DDS myself, but at 250mv output you will need a buffer. The buffer I built puts out about 6-8 volts p-p which seems to be plenty of drive for the V-II, and my DX-40 I have no problem achieving full plate current. With everyone running high tech rigs with tight filters a drifty VFO sorta sucks go the DDS route and don't look back.
  17. W5HRO

    W5HRO Administrator

    Those old 122 VFO's had the same problem as the VFO's that were built-in to all of the Johnson transmitters. The original stock 18K screen dropping resistor to the 0A2 regulator was only 2-watts which is too small and after 50+ years they are all pretty much disintegrated internally if they were never replaced. So if you find one that still has that old stock 18K resistor it won't last very long and it will start jumping around in frequency really bad until it craps out and dies. AKA, the Chernobyl resistor meltdown. The workaround is to just replace it with a 10W or more 15K resistor and it can even be one of the cheap wire-wound kind.

    You can make 122 VFO's pretty stable after replacing that resistor by DC regulating the VFO tube filament. Just use a 7806 regulator and make a voltage doubler using electrolytic caps and diodes and convert the 6.3Vac that is coming into the VFO from the Viking II. The 6.3V winding in the Viking transmitter has plenty of extra current so it's not an issue and the VFO has plenty of room to mount the caps and other components underneath.
  18. W6MQI

    W6MQI Member

    I actually built a separate power supply for mine, change the 18k resistor as well. All in all stability wasn't bad, but what I was really missing was dial accuracy yes I know
    what's the point of running an old rig like this and worrying about dial accuracy? Well I got tired of listening to the complaining that I wasn't where I said I'd be on the dial
    you know those CW guys are a persnickety bunch.
  19. WD5JKO

    WD5JKO Member

    There are lots of options for sure, and more a matter of preference. Sometimes I go down a road, pot holes and all, and get determined to make something work, even when there are better ways. If you can get a good frequency counter, and a RF tap from the transmitter, then the issue of poor dial accuracy is taken care of. The problem with frequency counters is the time base might not be precision, or take 20 minutes to be within 50 hz. I used an old LED type Fluke and added a 10 Mhz TCXO to replace the drifty 10 Mhz crystal. Now I am almost always within a few hertz of the 10 Mhz WWV signal.

    With a good frequency counter, then the VFO needs to be stable. A vintage 50+ year old VFO is a challenge to get stable. A drift rate of 300 hz per hour is pretty good, but not good enough anymore with more and more "channelized" frequencies. Many Ops will not use RIT anymore to tune in a station.

    The link below takes you to my 1958 Knight Kit VFO stabilization project. I had more than a few challenges. The result however is a VFO that stays within +/- 10 hz after about a 1-2 minute warmup. Kit V44 VFO Stabilized by the Cumbria Design X-Lock 3.0.pdf

    The results are illustrated here. The following link is a recording from last night on the 3870 Boat anchor net. I was running AM on a vintage SSB net.

    My part starts around 26 minutes into it. listen past my transmissions and hear what the next guy says about me.

    It can be done. :-)

  20. W5HRO

    W5HRO Administrator

    Most of the old VFO's can be made really stable. The issue is usually with 20-meters on up due to the fact they all work on harmonics on those higher bands. So if the fundamental drifts just the slightest bit then that drift gets multiplied on the higher bands. On 75-meters for example you can make them to where they will not even move if you regulate the tube's filament. Most of the time 40-meters is ok a well. I seem to remember Jim that your Knight VFO has a really funky fundamental setup which made it worse or caused another issue, but I cannot remember the details.

    I made my 122 VFO on the Viking II almost rock solid up on 10-meters by regulating the 6AU6 filament along with adding a small value cathode resistor to ground to keep a tiny bit of current always flowing through the tube and just enough to where you could not hear or see it in the receiver. Without keeping the tube just barely turned on like that it would drift slightly for maybe 10 to 15 seconds after I started transmitting on 10-meters until it stopped. When I added the small resistor to ground it pretty much kept it from happening. The problem is you have to change that resistor value as you switch to the lower bands to keep it out of the receiver, but it will work if you figure out a way to make it switch to those different resistors as you change bands. I had only the one resistor in mine though and used a SPST toggle switch where the CW key jack was on the back to switch the resistor to ground when I was on 10-meters, otherwise the resistor was left floating. A small rheostat on the back where the CW jack is with a knob to where I could have adjusted it for each band might have been a better solution, but I never tried it.

    The key thing first though is you MUST regulate the VFO tube filament with a 7806 DC regulator otherwise you are wasting your time unless you have a line conditioner in the shack that will keep your line voltage from dropping when you start transmitting. What often happens is someone will spot the VFO to a signal on their receiver, but when they start transmitting the line voltage drops so the VFO is no longer on same frequency where they spotted it to. It’s all about simple transformer ratios. If you have 124Vac on the primary of the 6.3Vac filament transformer winding in the Viking II transmitter at idle and get say like 6.5Vac out to the 6AU6 in the VFO and then that 124Vac drops down to say 116Vac when you start transmitting, then the VFO will automatically shift in frequency because that 6.5Vac output has also changed with it. It’s sort of like when you plug a lamp into the same wall outlet as the transmitter and notice how the lamp will dim in brightness when you start transmitting. One of the things I always hated and especially on 10-meters was how many AM’ers were never transmitting on the same frequency as the person they were talking to for the very reason I’ve just described.

    This is really all kindergarten level ham radio electronics knowledge stuff too.
  21. W5HRO

    W5HRO Administrator

    If anyone wants to know how to convert the 6.3Vac going to the 122 VFO to a higher DC voltage to drive a 7806 regulator then below are the two different circuits.

    The voltage doubler below will yield +9.7Vdc with the 300mA 6AU6 load on it.


    The voltage trippler below will yield +17.9Vdc with the 300mA 6AU6 load on it.


    In most cases the doubler circuit will work fine and you just connect the output to the input pin of the 7806 regulator and use a .1uF cap on each side of it right at the pins. In many cases the trippler circuit will be overkill, but that's what I used in mine because back when I did it we were having all of those rolling blackouts here in California with a lot of sagging in our line voltage on and off so I did the trippler just to be safe so it would always be high enough. I could probably convert it to the doubler circuit now since most of that power trouble we were having back then is over.

    Anyway, everything will fit in the bottom of the 122 VFO and you don't need any separate power supply for it. The 6.3Vac transformer winding in the Viking II has plenty of extra current available. And replacing R51 with a 15K 10 to 20 watt resistor will provide the 0A2 with just enough extra current to keep the screen voltage stable.
  22. K8CCA

    K8CCA Member

    The vfo122 is not putting a signal out with this transmitter but it worked with my other one. I almost have my dds vfo going so plan on using it. I built the dds vfo based on arduino uno and the AD9850 synthesizer from eBay and the buffer amp based on LT1253 op amp. The vfo is on loan from a friend, so I don't want to mess with it. It worked on my other Johnson Viking 2 transmitter. There is likely an issue with the connector.
    Thank for all the info. I do appreciate it, it's hard finding time to finish the dds vfo with spring time going on.
  23. K8CCA

    K8CCA Member

    One thing that confuses me is the harmonic use of the vfo 122. Is it going to be an issue to just generate the frequency with the dds vfo that I want to use on 15 or 20 meters?
  24. W5HRO

    W5HRO Administrator

    There was a guy just a few years ago who figured all of that out and came up with an equivalent DDS VFO for the 122 VFO. I believe his call was W9BHI. They (or N4YG) had the kits and info for doing it, but it looks like that is over now if you check out the website via

    I don't know these guys, but you might try to emailing N4YG or W9BHI and see if they will send you the details.

    I think the below was the 122 VFO equivalent W9BHI came up with.

  25. K8CCA

    K8CCA Member

    I based mine on the AD7C layout. I had it working when on the breadboard, and almost have it done in permanent version. The arduino controller is really cool. I modified the AD7C code to change the display to I2C comms instead of serial. It's been a fun project, but the programming took me a while to learn as I have never done any programming before. I am not sure how much I will use the Johnson transmitter on the higher bands, so perhaps it's not a concern.

    Here is the unfinished cabinet

    20160326_200644.jpg 20160407_133026.jpg