Johnson Viking2

[KE7KPB]

I;m working on a Vic 2 and so far I have replaced all of the paper and electrolytic caps and have checked and replaced any resistors that were out of tolerance. Checked all tubes and replaced if needed. This is where it goes wrong. I turned on the filament switch and everything lit up and no booms. hi hi. I started to test the transmitter and I was not getting any voltage for the buffer. Also when I turned on the plate switch, I saw the 6146s started to get red on the plate. I only had it on for about 10 seconds and turned off the plate switch. Rechecked the 6146s and no damage. Any suggestions on what to look for. I do have a complete manual for this. Oh BTW I am hooking up a VFO and a dummy load.

[WQ9E]

Check and make sure you don't have the polarity reversed for the bias filter caps (C12 and C13), these should be connected positive terminal to ground.  I would pull the modulator and final tubes until you are sure the bias supply is operational.

[KE7KPB]

When I was replacing the caps. I did make sure the positive side of the caps are to ground.

[WQ9E]

OK, I just wanted to double check because reverse polarity of bias filter caps is an easy mistake.

The Viking 2 has a clamp circuit to protect the final when there is no excitation.  The clamp control R-30 is adjusted so that the final just begins to draw a little current without excitation.  With the finals glowing red without excitation, the clamper circuit either needs adjustment or has a problem.

I assume you have oscillator voltage which indicates the B+ circuit is operational.  B+ is fed to the buffer plate via RF choke L20 and coil L5.  Lack of voltage here is most likely due to an open L20 but if this is the case locate the cause of failure prior to replacement.  Check resistance to ground from the V5 plate and try rotating C22 while checking to make sure there isn't a rubbing plate.  Either a short in C22 or C23 would cause excessive current draw and would result in L20 opening.

[KE7KPB]

Thanks so much for the info. 20+ years working on antique radios and breaking into transmitters. A all new ball game. Thanks.

[WQ9E]

You are welcome! 

Carefully check the 5R4 tube sockets and tube bases for carbon tracking.  This is a common problem with this particular tube given the combination of high AC and DC voltage on the tube base.  All it takes is a little dust and some humidity to create a carbon track.  If you catch it in time cleanup is simple but if it goes on too long it is difficult to clean and you may have to replace the tubes and/or sockets.

Once you get the Viking 2 running you should have a very reliable transmitter.

I have been spending quite a bit of time recently repairing several 1930s receivers.  In general, vintage AM/CW transmitters are simpler and easier to work on than receivers.  But DO BE very careful with the more dangerous voltage/current present in transmitters since they can easily result in electrocution.  Wear insulated shoes, remove all jewelry, and keep one hand in your pocket while making measurements.  Most importantly, know when to stop since fatigue leads to accidents which leads to estate sales. 

Welcome to the transmitting side of the hobby!

[Mike/W8BAC]

But DO BE very careful with the more dangerous voltage/current present in transmitters since they can easily result in electrocution.  Wear insulated shoes, remove all jewelry, and keep one hand in your pocket while making measurements.  Most importantly, know when to stop since fatigue leads to accidents which leads to estate sales.

Well said Rodger. A sign hanging over every transmitter work bench with advice like that might save a few lives. I'm living proof that some people get a second chance. I treat every circuit (now) as if it is hiding the golden BB. A bang stick at the ready and a clear head is a good start to any project.

Good luck with the Viking II Dan. I own one myself and it is one of my all time favorite vintage transmitters. Good luck with the repair work.

Mike

[KE7KPB]

Thanks for the reminder about high voltage. Working on antique radios, you can get a good shock. That is why I take special precautions when working on high voltages. Part time electrician and I do get around not only 480 but have worked on some of the line voltages. Before I get my hands in there, unplug, and discharge the caps, even a charged cap can give you a big bite. One does need to be reminded every one in awhile. Prevents picking yourself up off the floor or not being there the next day.

[WA1GFZ]

Check the drive level pot. An open pot is a common failure. It controlls the driver screen voltage

[AF9J]

I agree with everything that's been said so far.  My 2 cents? - DEFINITELY check the clamp circuit tube, and the clamp circuit pot.  Ask Roger, how my Viking II acted, when I fired it up for the first time - the plate current went through the roof!  After checking screen voltages, replacing the clamper tuber, etc., and a fair amount of head scratching, adjusting the clamper pot was done.  Normally, things should behave with a half turn's worth of adjustment on the pot.  Mine took over 2 FULL TURNS before things would settle down.  In a nutshell, not only had component values in the circuit changed in the umpteen years since my Viker had last been used, but somebody had replaced the original clamper pot, with an audio-type one.  

The moral of the story? - considering the age of these radios, assume that component substitutions have been made over the years, that may deviate from what the circuit, and parts list specify.  

73 & Good Luck,
Ellen - AF9J

[N8AFT]

 I had the same symptoms....You MUST have a key plugged into it or just a open circuited 1/4" plug in the 'key' jack to open the contacts. As it stands now it is in Key Down xmit mode regardless of mode sw position...  Good Luck you are on your way om...Lane.

[KE7KPB]

Between the flooding in Montana and all of the rain,I did get to do some work on the Viking. This is what is going on so far. When I first turn on the filament switch I see the meter goes up to 100 and then drops back down after the tubes warm up. but I still get nothing as far as the buffer tune up but when I adjust the drive the meter will go to 250. I did trow the plate switch and still the 6146 gets hot like there is a short causing high current draw.
I did measure 355 vdc on pin 3 for grid 2 on the 6146. I did check on L20 for it going open. I also adjusted the clamper pot and nothing happened. I did install a plug into the key jack. No difference on the meter adjustment.
There is zero rf output but the plates start getting red hot when the plate switch is turned on for a very short time. What voltages should I expect on the 6AQ5 and the 6146s. I wish the rain would quit for awhile.

[N8AFT]

 Well, mine decided to take up smoking today,T2 is toast.

[KE7KPB]

Ouch, What happened? 

[N8AFT]

 Left it with Filament on and plate off, hrs later smelled smoke. T2 was red hot...Are you sure you have a Key plugged in to your rig?? Sorry if that's a dumb question om...lane.

[KE7KPB]

Yep and the plug is from the same vintage. I can take some pics if this would help. Good luck on your rig. Once I get the transmitter up and running I am going to install everything in a server rack. with the Henry 2kd on the bottom with the viking then the National 50 on top. Well that is the plan so far.

[N8AFT]

  Fine Business om..No mine's fer sale now, It was >3/4 done...Oh well, no time to work with it. I presently run rice boxes and get along well, I wanted a BA station but without having a real shop it's an 'outta reach' goal...laner

[WA1GFZ]

These old rigs were designed to work at 110VAC. When plugged into a 120 or 125 volt line T2 is very close to saturation. The resting magnetization current is a lot higher. When I solid stated my V2 cDC  I put the 5 volt windings in series with the primary to increase primary inductance. This also reduced the heater volatge from 6.8 to 6.3VAC. Now the transformer runs maybe warm after many hours of operation.

[WQ9E]

It is best not to leave vintage gear "cooking" when you are not close by.  The Viking II specs are shown at 115 volts and I don't notice any abnormal heating on my typical 118-123 volt service. 

With transmitters, it makes sense to separately fuse the low B+ and other auxiliary transformers since a shorted filter cap or other failure will cook the relatively low power transformers long before fuses designed to handle the entire transmitter draw will open.  I nearly cooked the wiring harness in my Viking 1 after I replaced the pilot lamp with a brand new one that had a direct short in the base.  The filament lead in the bus started cooking but the fuse wasn't concerned at all.

[w1vtp]

Left it with Filament on and plate off, hrs later smelled smoke. T2 was red hot...Are you sure you have a Key plugged in to your rig?? Sorry if that's a dumb question om...lane.

With the "fil" on that includes the LV supply (same xfmr).  Did C10 / C11 check out OK?

Fusing T2 separately makes a LOT of sense.  Think I'll look into that for my V 1 & 2.

F1 is supposed to be 5 amps.  That's a bit too high for T2, I think

Al

[N8AFT]

Al, yes I agree on the primary fusing being a bit too much.Extra protection on secondary is what's needed.It was working fine, but it is 55 yrs old too...lane