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Author Topic: Johnson Viking Adventurer HV filter caps?  (Read 45461 times)
KC2VDM
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« on: October 04, 2011, 06:40:01 PM »

Hi, I just picked up a Viking Adventurer. I'm currently working on restoring it and am having issues finding replacements for the two 8uF 700VDC Electrolytic filter caps. While I know how to gang up capacitors (I'll probably use 2 16uF 450VDC Axial Lead Electrolytic's in series for each cap), I really haven't bought any online before.  And yes, the previous caps have already released a bit of their goo, so leaving them in is not an option.

Can anyone recommend a good site for these, where they don't require a buy 15 of them, or cost $20 per cap.

Those are the only caps I need to replace that I don't have. I'll leave the Mica's alone, And have already replaced 2 or 3 Ceramic disk's that looked on their way out. Really these Two caps are the only thing keeping me from finishing my Vintage station, Except crystals or a VFO, but that's a different story.

And thanks guys for all the help with the  hot 129X Transformer.

-Alex
KC2VDM
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N4NYY
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« Reply #1 on: October 04, 2011, 06:55:23 PM »

John,

Use these instead. They are 18uf which is a more common value. The reason 16uf is so expensive is because it is not a common value.

The 1uf is 12.5% greater in the original value, which may be within tolerance. Some of the gurus here can tell you if this is not a good idea.

http://www.mouser.com/ProductDetail/Nichicon/UPZ2W180MPD/?qs=sGAEpiMZZMtZ1n0r9vR22ZuL814NfPubzNcIgKfyxnE%3d

Mouser has no minimum order. When you check out, select USPS priority mail, but in the notes field, state USPS First Class or cheapest way. They will send it out cheapest way.
« Last Edit: October 09, 2011, 08:06:11 PM by N4NYY » Logged
W8JI
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« Reply #2 on: October 05, 2011, 04:57:53 AM »

It won't hurt to bump the capacitance up a bit in that rig. Use a pair of something around 20-25 uF 450 volt in series with 100K 2 watt metal oxide resistors across each.
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KC2VDM
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« Reply #3 on: October 05, 2011, 05:32:46 AM »

Why do I need resistors? Huh
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G3RZP
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« Reply #4 on: October 05, 2011, 06:00:00 AM »

You need resistors to equalise the voltage across the electrolytics. This is because the electrolytics will leak a bit and not necessarily equally - reason 1. A direct (as opposed to alternating) voltage applied across two capacitors in series will divide in inverse ratio to the capacitances, and electrolytics are usually something like -20 + 80 % tolerance on capacity - reason 2. Of these two effects, the leakage is usually, with electrolytics, the dominant factor
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W8JI
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« Reply #5 on: October 05, 2011, 06:12:26 AM »

Also to not shock yourself later, or ruin a capacitor from reverse charge on power down. The resistors make sure each capacitor bleeds down, and one does not reverse charge equal to the other.

One resistor across each cap. Then they go in series.
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N4NYY
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« Reply #6 on: October 05, 2011, 06:14:10 AM »

If you take Tom's advice, here are the resistors.

http://www.mouser.com/ProductDetail/Nichicon/UCS2W220MHD/?qs=sGAEpiMZZMvwFf0viD3Y3VtTL3hlGy6IiaB5fK2RRfI%3d

I gave you the radial leads. If you need axial, it is a different part number.
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KA5N
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« Reply #7 on: October 05, 2011, 06:47:49 AM »

Ah!  The Viking Adventurer.   Nice little transmitter.  The only thing is that the plate current meter demands attention because as you key the rig the needle of the meter swings back and forth all the time.  You get used to it.
Have fun
Allen
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KC2VDM
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« Reply #8 on: October 05, 2011, 08:34:02 AM »

Now I get it. Thanks for the advice on resistors. And the radial lead caps will works fine (eaasier to solder the resistors on to also).

I need to find a NOS meter for the rig also. Someone replaced it with a 10mA meter (even including the bent pointer! Grin ).

I cant wait to see that 807 glow! I saw on a video that when keyed,  the tube glows a luminescent purple. I wonder if thats true?

-Alex
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N4NYY
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« Reply #9 on: October 05, 2011, 08:51:41 AM »

Quote
I need to find a NOS meter for the rig also. Someone replaced it with a 10mA meter (even including the bent pointer! Grin ).

Damn. I just sold a Viking II ma meter on ebay for like $12, in nearly perfect shape. Another one sold for $60 which was in worse shape than mine. Go figure.
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AC5UP
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« Reply #10 on: October 05, 2011, 09:20:10 AM »

Damn. I just sold a Viking II ma meter on ebay for like $12, in nearly perfect shape.

Yeah............. And last month I threw out a box of...............

BTW: If anyone wanted to cruise through a really nice assortment of popular vintage radio squizzmatics to increase their appreciation for how many different ways a radio can be built using five tubes, this would be a good place to visit: http://makearadio.com/beitmans/index.php

Most of the scans are remarkably clean & legible.

As for 807's experiencing Purple Haze... Any power tube with sufficient high voltage will tend to show some corona. Push 'em a little further and you can do home X-Rays.  Shocked
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KA5N
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« Reply #11 on: October 05, 2011, 10:42:15 AM »

The meter in the Adventurer is an iron vane type (very very cheap) and unlike D'Arsonval movements which are damped the needle or pointer wags back and forth across the meter face.  Many folks replaced these meters since it is difficult to see what you are doing when you tune up.

Allen
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N2EY
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« Reply #12 on: October 05, 2011, 02:30:47 PM »

The advice by others about series caps for the Adventurer is all good. You can go a bit bigger, particularly on the output cap.

IMHO the Adventurer was a very good rig for its time. The price reflects it - $54.95 as a kit. If you take 1957 as the base year, that price inflates to $420 in 2010 dollars (!)

Except crystals or a VFO, but that's a different story.

Crystals are around but unless you get lucky they're not cheap. Two VFO suggestions:

1) W1ICP's "Easy To Build VFO" in QST (February 1962)

PDF at:

http://jlandrigan.com/files/McCoy%20VFO.pdf

2) W2EWP's surplus VFO in the book "Command Sets".

Go to:

http://www.mines.uidaho.edu/~glowbugs/arc5pages.htm

and click on

#6

to download the book "Command Sets" in PDF. It's 15 Mb and has lots of info.

On page 87 is the "Low Cost VFO" by W2EWP. Although he used a 3.0 to 4.0 Mc. tx, it's a simple matter to use a 4.0 to 5.3 Mc. one and add padding capacitance to bring it down to 3.5 Mc. at the low end. I made one some years back and it's well worth the effort. I used a 12SK7 instead of the 6AG7 he used, and had plenty of output to drive a 6AG7/807 MOPA - which is exactly what the Adventurer is.

---

There are at least three kinds of blue/purple glow in radio tubes that I know of:

1) Gassy tubes will have a bluish glow throughout that varies with cathode current. Such tubes are usually bad.

2) Some tubes, particularly those handling considerable power, will exhibit a bluish glow only on the inside surface of the glass. This is flourescence caused by electrons hitting the glass, and is perfectly harmless.

3) Not all radio tubes are vacuum tubes. VR tubes such as the 0D3/VR-150, thyratrons and control tubes such as the 884, 0A4G, 2D21 and 2050, gas rectifiers such as the 3B28 and mercury-vapor rectifiers such as the 866, 872, 83 and 816 all have characteristic glows which are perfectly normal (and quite pretty, really).

What size is the meter hole in the Adventurer?

73 de Jim, N2EY
« Last Edit: October 05, 2011, 07:08:10 PM by N2EY » Logged
KC2VDM
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Posts: 145




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« Reply #13 on: October 05, 2011, 04:54:40 PM »

The inside diameter of the hole is 2', the outside square is about 2x2 square. I say about because I haven't taken into account the meter cover's metal thickness (probably 1/16). Right now, it looks like someone put a smaller meter in, but with some metal curled up around it, to make it fit in the hole.

Thanks for the articles on VFO's, I'll check them out later tonight. I've got plenty of tubes that are begging to be used in such a project.

And yes, I've seen what gasey tubes look like, Heres a perfect example of a gasey tube, and a knucklehead killing one! Grin http://www.youtube.com/watch?v=nCKLLeSkvB4&feature=related

-Alex
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W0OPW
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« Reply #14 on: October 05, 2011, 05:07:44 PM »

Alex-make absolutely sure that the fuse is 2 amp and not the 5 amp originally installed. You will burn up your transformer with that 5 amp fuse. I know because after burning up the first one in 1958, I burned up a 2nd one 40 years later at which time it all came back to me about the fuse  The burning insulation smelled exactly the same after that much time-amazing.
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