Johnson Viking II has landed on the bench

[KD6VXI]

Picked up a viking II today.   175 bucks,  supposed to work,  non ham,  etc.   No Xtal.   No way to test.

Tuned it up on 40, with the Xtal I found inside the chassis.   Got about 110 watts on CW.   Am,  wonderful carrier,  and about 10 pct modulation.   Mic or sig genny driven.

Also,  it will drift up in plate current.   Load it up,  flip switch off.   Turn plate switch back on,  once in a while you'll see the plate I slowly climb,  then peg,  then blow the fuse.   

Owned a valiant 20 or more years ago.   

This one came with the original manual for both the transmitter and the vfo (122 model,  which wasn't available or on location).

Crystal won't heterodyne to 11, so I think it's a virgin there.   Crystal switch is locked on position 4.  Pulled know off,  loosened coupler and removed shift   put some steel wool to the point it exits the chassis.   Helped with rotational firmness,  but the switch is still locked up tight.

Tried radio shack tuner cleaner and lube.   Didn't help.

Any quick ideas to check?   Going to have to recap the entire transmitter.   But,  as clean as it is,  and for the price,  I wasn't going to pass it up.

--Shane
KD6VXI

[WQ9E]

Shane,

Replace the bias filter caps and the audio cathode bypass caps.  Both are typically bad, the bad bias caps will cause unstable plate current and the cathode bypass caps will cause very low audio system gain.

The climbing plate current could be due to a gassy final tube also.

The audio driver transformer is a known failure item but since your transmitter has some modulation this probably isn't the issue.  When these fail it is usually because of an open winding; it results from the very fine wire being corroded by the acidic insulating paper. 

5R4 rectifiers are very prone to carbon tracking from dust so make sure to clean the sockets and the tube bases of any buildup.  I had to replace one 5R4 socket in my Viking I because of arc damage.  This isn't just a Johnson issue but applies to all transmitters running the 5R4 tubes at significant voltage.

Since your crystal switch was frozen be sure to lubricate and carefully check the switch controlled by the 160 meter in/out control.  I have seen the actuating drum shear off this switch when it becomes stuck.

[w1vtp]

Is this a kit V2?  Check the tube sockets for rivets = not a kit but factory wired.  If it's a kit (screws attaching the tube sockets in place) then cold solder joints can be a problem.  That's what I had with my V1  Fixed the cold solder joint from the driver transformer to the 807 grid and good mod. 

Replace the LV & bias electrolytics. 

As far as frozen rotary switches first cure attempt, use liquid wrench.  If that doesn't work then heat should do the trick.

[WB5IRI]

Drifting plate current could be a bad coupling capacitor. Had that on my Valiant. Replace all caps! But be aware that high voltage replacement caps from places like Surplus Sales of Nebraska are usually just as old as the parts you are replacing and may also be bad. Had a bad doorknob cap that took me forever to find because I had just bought it and knew it couldn't be the problem. Wrong!

Doug