Johnson Viking II sending carrier with plate off

[KC3GMQ]

Hi all, Me again.   While I wait for a part for my Apache I have been posting about, I acquired a Johnson Viking II.  So I load the transmitter, everything works as the book says, but I am getting a carrier showing up on my panadapter at the same frequency as the crystal installed with the plate power turned off.  Im baffled.  I am including two pictures of the panadapter,  one with plate off, the other with plate on.  Transmitter is set up for max power at 230ma. The carrier is small, but is plenty to saturate my receiver and make it useless.  Any Ideas?  I have done internet searches and maybe I am not entering them right, but I can find nothing about this.  I have checked my grounds several times too.

Thanks
73
KC3GMQ Dave

[WD8BIL]

Is the signal still there with the phone/cw switch in the phone position?

[KC3GMQ]

The signal is there in phone , or in CW key down,  both set ups with plate off.

KC3GMQ Dave

[DMOD]

BIL is on point.

If you look at the Upper Left of your schematic for SW3C, you will see that in the CW position the cathode of V6 (6AU6) is grounded all the time because of J2. In the Phone position, the Osc. is only activated in Keydown.



Phil - AC0OB

[KC3GMQ]

I checked J2,  it is working,  But excuse my lack of knowledge,  I understand what you mean when you say it is grounded until keydown.  So are you saying, the issue is because it is not being grounded someplace and that is what I need to trace out and look for?

[W2PFY]

I think if you put a 1/4 plug into the keying jack, the osc may turn off?

[KC3GMQ]

I tried the 1/4 plug,  didnt work. My lack of experience in electronics isnt helping 

KC3GMQ Dave

[N1BCG]

For greatest confidence, be sure the 1/4" plug is unwired, meaning it's just a plug and that it's a three conductor (tip, ring, sleeve). That will ensure that the circuit is getting broken.

Ok, off to go find a Viking schematic ...

[KC3GMQ]

Ok  I tried an un-wired 3 three conductor 1/4 plug and it didnt help

[N1BCG]

Can you post a schematic? I thought it would be easy to find one online but for some reason it's not happening for me.

[KC3GMQ]

would you like me to email you a copy of the book?

[N1BCG]

That's a lot of fuss, but the schematic page would be super. Of course if you post it here then others can check it out as well.

[KC3GMQ]

Ok  Having minor issue uploading it,  Ill get it here shortly

[KC3GMQ]

Johnson Viking II Schematic.  Anyone who wants, needs manual I would be happy to send a copy.

[N1BCG]

Perfect! What's happening is that the oscillator is always running, and that could happen if the cathode of the oscillator tube has a path to ground. With the power OFF, measure the resistance from pin 8 of the accessory jack and ground. It's possible that a capacitor C15 or C50 is shorted. Or, they have a low enough resistance to allow enough current through the tube for oscillation.

[KC3GMQ]

Pin 8 to ground is open,  the accessory jack is the octal plug receptacle on the back I am assuming

[N1BCG]

I'm still thinking there's some resistance, even if just at high voltage. Ok, here's another test, measure the voltage at pin 8 with a sensitive voltmeter. Keying is not necessary. Switch between CW and AM and note any differences.

[KC3GMQ]

I'm still thinking there's some resistance, even if just at high voltage. Ok, here's another test, measure the voltage at pin 8 with a sensitive voltmeter. Keying is not necessary. Switch between CW and AM and note any differences.

Ok  I have 40vdc in CW and 0 in Phone.  No plug in CW socket

[W2PFY]

While we are reaching for stars here, you might want to replace the osc tube. There may be a short from the cathode to the filament? I think it is a 6AU6 tube but me eyes aren't what they used to be.

[KC3GMQ]

I already replaced the 6AU6.  Figured it was worth a shot.  Thank you for the advice it is all welcome.


73 Dave

[W2PFY]

Are you getting any meter reading in the OSC setting? It is in the cathode circuit and if the reading is zero, I would think that there is a short in that circuit. That is what I think it is anyway since it is always on.  Too bad no one with the same rig as yours has not commented so far but they probably will, once they see your question.

[N1BCG]

Something is completing the cathode circuit. Does the frequency change with the selected crystals or VFO frequency? Also, can you tell if the frequency changes between CW and Phone? That would indicate a difference between a known hard closure and a leaky cap.

Unless someone has a better idea, I'd try unsoldering C15 and C50 to see if either is conducting.

[KC3GMQ]

Everything sets up just like the book tells you how to load it, once I got it loaded, I noticed a carrier.  So I have stopped to find the reason it has that carrier when the plate is not on.  It sets up real nice though,  better then any of my other radios.  I am used to the heathkit manuals,  made for dummies like me who are trying to learn all of this.  The components are fairly easy, its learning what is going on, why, and what is making things do what they do that is taking me some time.

[KC3GMQ]

As far as I can tell the crystals are the same in either CW or Phone.  I have 3 crystals 7295, 7290, and 7285.  All were about 3 k off from what my main modern radio was indicating.  I changed out the 6AU6 for a new one and that gap dropped to 1kz. The more I look the more I am finding.  The radio looks great inside, but I can see a mode or two added.  I am going to trace them out and most likely remove them.  Looks like some sort of transfer switch was added.  Think I will re cap also, all the caps are originals.  I would have done that first, but I dont see how any of them would cause this issue. I will do C15 and C50 right now.  If ones bad, I will have to get some.

[W2PFY]

The reason I asked if you were getting a reading on the OSC is if you are not, the problem may be down in the selector SW itself or something associated with it.

Like shorted caps at the meter C-46 & C-47