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Johnson Viking II sending carrier with plate off




 
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Author Topic: Johnson Viking II sending carrier with plate off  (Read 9211 times)
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KB2WIG
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« Reply #200 on: April 18, 2017, 01:18:00 PM »


You may wish to consider getting some "high current, high voltage" doe knob caps.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.X330+pf+doorknob+capacitor.TRS0&_nkw=330+pf+doorknob+capacitor&_sacat=0

The 'stuff' that Viking used are rated at ~500 Volts ( the c38 at 1200 V). Get some of these knobs and never have to worry(?) about them going bad. You could fit most of these, or just a few, into the available space.

Murphys law design, at least use them for the "160/80m positions";  your switching out capacitance when you go up in freq, so placing the physically large, higher voltage caps in the 'lower' positions can be of benefit. --- load up yer 25' 160 meter  vertical can produce some very, very interesting values.

More info than you wanted, but if your going in and replacing things......


klc


klc

I've purchased from this guy....    http://stores.ebay.com/valtek2005/  no problem,
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DMOD
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« Reply #201 on: April 18, 2017, 01:27:05 PM »

Quote
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?

That will work.

As far as the 300 puffs go, I would replace the silver micas with the ceramic types rated at > = 2kV.

AES has these 330 pF at 3kV for 0.45 a piece:

https://www.tubesandmore.com/products/capacitors?filters=Type%3DCeramic%20Disc

and Mouser at:

http://www.mouser.com/ProductDetail/Vishay-Cera-Mite/564R30GAT33/?qs=sGAEpiMZZMt1mVBmZSXTPI4RnmSwHRBuLinJuYdYBsM%3d


Phil

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KC3GMQ
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« Reply #202 on: April 18, 2017, 02:10:54 PM »

The ceramics are ok in place of MICA?
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DMOD
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« Reply #203 on: April 18, 2017, 08:27:54 PM »

The ceramics are ok in place of MICA?

Yes they are. I find them to be more reliable in Pi-Net loading applications.

Now for frequency determining circuits such as VFO's, the lower voltage micas may have a slight edge.

And the nice thing about ceramics is you can get them at higher voltages than equivalent value mica's for a lower cost.


Phil - AC0OB
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KC3GMQ
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« Reply #204 on: May 03, 2017, 12:19:33 PM »

Hello all,  sorry it has taken me this long to get things done.  Ok, so I have the Caps replaced in the Coupling.  This had no effect on it at all, transmitter on 80M still is more then fully coupled at the first (#1) coupling position (Grid 6ma, Plate 250ma).  I have checked my antenna, SWR 1.3 on 80M and I use a tuner to tweak that down to 1.1.  The Viking loads exactly the same whether I use a 50 ohm dummy, or the Dipole antenna. I have checked all the hardware tight, I loosened and then re tightened them all.  Looking for the next direction to take now.

73
Dave KC3GMQ
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N1BCG
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« Reply #205 on: May 03, 2017, 04:29:52 PM »

The next step is to see if the Coupling control is actually switching in the proper capacitor combinations. You can do this with a capacitance checker or even a simple ohmmeter. Be sure the rotary contacts are clean (pencil erasers make excellent contact cleaners).

Also, does the loading change at all in the first few positions of the Coupling switch?
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« Reply #206 on: May 03, 2017, 05:12:47 PM »

Ok so I made a video and you can see how I am loading it, and that the capacitance just makes the plate rise and I cant get it below 250ma.  Going to work on the switch now with my eraser, Hope the video link to youtube works

https://youtu.be/R5iQEN0IroE
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Pete, WA2CWA
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« Reply #207 on: May 03, 2017, 08:20:36 PM »

Is the 160 meter switch in the Out position? Can't tell from the video. You should verify that the actual switch is in the "out" position.
For final amplifier tuning (the big knob) the scale should be somewhere between 15 to 25 for 80 meters. Anything higher and you could be trying to dip on a harmonic frequency.
With the final amplifier tuning window set to roughly zero, you can tune the oscillator and buffer up, then drop the grid down so the plate current maybe reads 50 to 75 ma. (or some low value) and start cranking the "big knob" for a pronounced dip as you move up the scale. I think on my Viking II I had at least two dips but only one was a pronounced dip.
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« Reply #208 on: May 05, 2017, 11:00:35 AM »

I think I found my Coupling issue,  As I was digging in to clean the switches lol, they are pretty bad,  I found that one of the contacts is burned off.  I am going to remove the switch, clean it, and try and make a makeshift contact.  I have done this once before.  I bent a small piece of hookup wire and soldered it on.  If there is a better method, I would love to know about it Smiley


* Coupling Switch.jpg (908.37 KB, 915x1101 - viewed 95 times.)
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w1vtp
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« Reply #209 on: May 05, 2017, 05:19:02 PM »

I would NOT  be switching between the loading positions with the plate on.  Good way to prematurely kill that switch.  Where you are getting too much current and not a very pronounced dip you have either the condition that Pete indicated or you have a position on that stepped loading control already burned out.  Or maybe one of the fixed loading caps is no longer working.  You should be able to get a good pronounced dip with light loading (all the loading caps switched in).  Unless you are trying to tune for the second harmonic as Pete has indicated which will not produce as pronounced dip + you might get one of those coveted pink ticket if you're hooked up to an antenna.  The instruction is pretty good about that section in the manual.  At those current levels, you are really beating the he!! out of those 6146's

a
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KC3GMQ
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« Reply #210 on: May 05, 2017, 05:45:37 PM »

Thanks for the last two posts. So I made a repair to the switch. Still loaded the same. I have no issues on 40m and higher. I did play a bit and is I destine the antenna, I can load more to the antenna...  So I am tuning to the first dip, it was at about 25 on the big knob like mentioned previously. All switches are. Lean now too. I will add, The Transmitter is how I received it. I will admit, I am also learning as I go. So far it has been fix one issue and find another. The loading switch will need a better repair, or replacement. And FYI, I replaced all the loading caps.
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Pete, WA2CWA
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« Reply #211 on: May 05, 2017, 06:30:16 PM »

You didn't answer whether the 160 switch is in or out. Should be out for all bands except 160. Check/verify that switch since it's on a pulley system.
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KC3GMQ
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« Reply #212 on: May 05, 2017, 06:34:58 PM »

It is out, checked and cleaned that switch also
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w1vtp
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« Reply #213 on: May 06, 2017, 04:53:57 PM »

If you are still not getting much of a dip, I'd start replacing the fixed loading caps.  I believe these caps have a history of failure.  If any of these caps open up, the final could be over coupled and that would result in high dip which will damage the 6146's (due to high plate current) and will result in flattopping on the modulation peaks which will in turn result in buckshotting or splatter.  So, that problem needs to be addressed

One point I want to verify is that you are tuning up with full grid drive (4 to 6 ma).  I thought I saw you turn the drive back to zero after checking the driver peak that it would give the required drive.  I cannot imagine turning the drive down and then trying to do the plate circuit tune up.  

The final point is that if you have a "healthy" tank circuit, you will get a pronounced dip going to a relatively quite low plate current.  If you cannot achieve this pronounced dip then the tank circuit needs to be fixed.  That's assuming a grid current of 4 to 6 ma.

a

PS: I just took another look at that loading switch.  That's the worse corrosion I have EVER seen.  That switch needs to be shiny. If it cannot be make to be shiny then it should be replaced. That could be your problem
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KC3GMQ
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« Reply #214 on: May 06, 2017, 06:14:30 PM »

Alan, when you saw me return the drive back to zero, that is right after I set the buffer and the book says to go to zero before turning the plate on. After the plates on, I go up to 100ma, dip, then check grid. This is the point where the issue is. Once I've done the initial plate dip, and checked grid at 6 you start loading the antenna. My problem is, on 80m, at position #1, after the first dip I'm at 250ma on plate with 6ma of grid. That's fine for CW, but phone says max 230ma of plate. All loading caps have been replaced with new. Coupling switch is repaired and shiny clean.

Dave KC3GMQ
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« Reply #215 on: May 09, 2017, 11:35:20 AM »

Makes me wonder if you have a CDC coil set installed instead of the normal Viking II coil set.

Try these settings for 75M:

FREQ Sw - 3.3 - 4.5,
Drive 2,
MinMax coupling - 4
Coupling Sw. - 2.3 to 3.5.


Phil - AC0OB
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KC3GMQ
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« Reply #216 on: May 10, 2017, 01:03:54 PM »

Well I am calling the Viking II complete.  I do not have a smoking gun cause of the coupling, But it is working now.  I was able to get on 3873 the other night and rag chew a bit.  Been leaving the transmitter running to keep it warm lol,  but it is loading and transmitting good now.  Hoping it is not something more intermittant and it will be good and reliable now.  I am thinking the new caps, switching cleaning and repair did the trick. 

73
Dave
KC3GMQ
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