Johnson Viking II sending carrier with plate off

[KC3GMQ]

The 470Ω resister went between pin 4 and pin 7, Pin 4 is heater ground... there is no, nor was there a cap on pin 7 to pin 4.  I do have a 10uf electrolitic going from pin 7 to ground, polarity checked also.  Ill look in assembly manual for a cap

[KA2DZT]

Have you checked the value of the screen resistor?? It may be off value.  I don't have a schematic of this VII so I'm just making a few comments based on what these circuits usually are.  Maybe I can find a schematic to look at.

[KC3GMQ]

I have checked them, all good so far.  I will attach a copy of the schematic.

[KA2DZT]

OK great, I just when back through all the pages of your thread backwards 8-7-etc.  Found the schematic on pg 1.  only to come back here and find you re-posted it again.  

Anyway, V2 6au6 is being run like a triode.  You will see the screen resistor (22K) is connected to the plate.  So the screen voltage is going to be high, almost the same as the plate voltage.  Don't worry about that, just make sure the screen resistor is 22K.

If you look at V1 6au6 you will see the difference.  There the tube is being use as a pentode.  Notice the screen resistor is connected to the B+ before the plate load resistor.  Also notice the 1meg value for the screen resistor.  The screen draws only a few ma so your need a very high value resistor to bring the B+ down the normal screen voltage level.  This is not the case with V2 where the screen is being used as an added plate (like a triode).  The 22K resistor is just there to limit the screen current and to slightly reduce the screen voltage from the full plate voltage.  This helps to ensure that the plate draws most of the total plate and screen current.

V2 6au6 could have been 1/2 of a 12au7 (which is twin triodes)  Instead of a 12au7 V2 should have been a 6c4 triode.  Johnson probably used a 6au6 for V2 because they had a ton of them and maybe cheaper for some reason.

Fred

[KC3GMQ]

Signal tracer at the cathodes of both 807's sound was strong and clear and responded well to the Audio potentiometer.

[N1BCG]

This is great news! The only thing left are the 807s themselves and the mod transformer. Are all the voltages within spec on both 807's pins?

[KB2WIG]

 Time fer an air check?

klc

[KC3GMQ]

ill load up on 7290

[KC3GMQ]

Well all, I guess its working ...I did some test calls on 7295, I had 2 come backs who reported my sound as loud and clear.  I will try and get on the bands tomorrow and we will see what the experts have to say.  I can not thank all of you enough who have helped me through all of this.  HAM's are the best !!!  yes a little gushie hahaha

[N1BCG]

I heard a little bit of that but the static was intense. Drop me an email if you'd like to set up a sched. It would be nice to hear the results...

[KC3GMQ]

I bought a VFO should be here any day. That should make it easier to get on another band instead of crystals. I will email. Thanks again for all your help

[DMOD]

If you decide to do any upgrading, here are a few suggestions:


Phil

Added RF Filter Circuit and Clamp Circuit improvements.

[KC3GMQ]

Thank You

[KC3GMQ]

Think I have most of the bugs out of the Viking now. One thing that isn't quit right is on 80M everything works but it loads completely on the #1 position of the coupling and I can't get plate below 250ma. Any ideas? Could it be the capacitors on the coupling switch? All other parameters are in spec

[KB2WIG]

A WAG, try measuring the meter shunt...  u never know.Maybe feed 200 mA through the meter and see.

While yer at it place some SS diodes across the meter.


KLC

[KC3GMQ]

Ok I know im lost but a WAG? and SS diode?  Is that a schottkey diode?  Also, When I load on 40m, it all works like a charm, just made me thingk when I loaded on 80m and i didnt have to couple the power, and then its a bit high. 

[KB2WIG]

Sorry..... Wild  *ss Guess.
      SS diode = Solid State diode.
            Sometimes, writing a responce on the telly phone keyboard makes fer a poor
                 communication.


Klc

[KC3GMQ]

LOL,  Guess I should have asked my kid to translate hahaha.  I should have known

[KB2WIG]

Well, at least no one started talking about Nazi diodes.........


klc

[N1BCG]

The lower the frequency (band) the more loading capacitance is needed, so problems with those caps will be more noticeable on 80 than 40, 20, etc.

Can you get any better dip at the top of the band around 4mc?  I'm also assuming that you're tuning up into a 50Z load. An antenna mismatch can do that as well.

[KC3GMQ]

Acts the same with dummy or antenna. I suspected the dipole, so I rubbed it dead on for 3885 and with a swr of 1.3 still loads right away

[N1BCG]

Sounds like a loading cap went bad.

[KC3GMQ]

I will check the caps next

[DMOD]

See Figures 3 and 10B in the manual.

Most likely one or more of those 300 pF (C33 to C38) caps have decreased in value.

Also make sure the variable capacitor (C29 and C30) mounting screws are tight.



Phil - AC0OB

[KC3GMQ]

Phil, thanks for the reply, after reading a bit last night, I'm thinking I should just replace them all. I was going to order the silver mica dipped???  Also the 150pf 1200 volt I can't find. Was thinking on ordering 2 300pf 1000 volt and installing in series. Am I on the right track?