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Author Topic: 3-500 Filament Problem with Henry 2K Classic X  (Read 24626 times)
W8KR
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Posts: 28




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« Reply #30 on: February 27, 2014, 01:10:50 PM »

N7BMW and W1QJ... OMG N7BMW's idea worked!  The spring came right off, I bent it with a pliers and put it back on and it's closed right back up!  It took me all of about two minutes!  I may have bent it a little too much because the opening for the pin is now smaller than the other clips, so I may have to take it off and resize it but that would be very easy.  How the heck did you figure that out?  I would never have seen that the filament clips come apart!

W1QJ... Lou, yes, the faulty pin clip is positioned in a way that I could indeed drill out the rivet and put in a new clip.  I may still want to do that depending on how N7BMW's fix works out.  However, I would like to talk to you about your earlier comments on the 2-K filament circuit.  Could you send me an e-mail and exchange phone numbers with me?  My address is jack@falkerinvestments.com .

73,

Jack W8KR
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W8KR
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Posts: 28




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« Reply #31 on: February 27, 2014, 03:26:23 PM »

I have now re-tensioned both of the filament pins on the E. F. Johnson socket that is giving me trouble, using Brian, N7BMW's very innovative fix.  I plugged a tube into the socket and it fits perfectly.  I had been a little concerned that I had over-tensioned them, but no problem.

Now, while I'm at it, I would like to clean the inside of all the pin clips.  Does anyone have a suggestion of what I can use to clean the clips without rubbing off the silver plating?

73, Jack W8KR
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W8JI
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Posts: 9748


WWW

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« Reply #32 on: February 27, 2014, 03:44:31 PM »

I have now re-tensioned both of the filament pins on the E. F. Johnson socket that is giving me trouble, using Brian, N7BMW's very innovative fix.  I plugged a tube into the socket and it fits perfectly.  I had been a little concerned that I had over-tensioned them, but no problem.

Now, while I'm at it, I would like to clean the inside of all the pin clips.  Does anyone have a suggestion of what I can use to clean the clips without rubbing off the silver plating?

73, Jack W8KR

There are a few ways to do that.

An ink eraser soaked with WD40 works, if you clean and residuals off the contact with a solvent. That may be tough to get in there.

What I have done is wrap clean typing paper around a drill shank that is slightly undersized, and soak it with WD40, and spin it in the pin. But you still have to clean any residual off with a solvent that leaves no trace residues.

73 Tom
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W8KR
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Posts: 28




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« Reply #33 on: February 27, 2014, 04:04:46 PM »

Tom... I like the WD-40 idea but what would u suggest as a solvent?

Did u have a chance to read my e-mail from yesterday?
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N7BMW
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Posts: 215




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« Reply #34 on: February 27, 2014, 04:16:28 PM »

N7BMW and W1QJ... OMG N7BMW's idea worked!  The spring came right off, I bent it with a pliers and put it back on and it's closed right back up!  It took me all of about two minutes!  I may have bent it a little too much because the opening for the pin is now smaller than the other clips, so I may have to take it off and resize it but that would be very easy.  How the heck did you figure that out?  I would never have seen that the filament clips come apart!

W1QJ... Lou, yes, the faulty pin clip is positioned in a way that I could indeed drill out the rivet and put in a new clip.  I may still want to do that depending on how N7BMW's fix works out.  However, I would like to talk to you about your earlier comments on the 2-K filament circuit.  Could you send me an e-mail and exchange phone numbers with me?  My address is jack@falkerinvestments.com .

73,

Jack W8KR

I would not worry about it being too tight unless you can't get the tube plugged in.

How did I think of it?  Someone here recommended replacing the sockets during my rebuild.  I studied the sockets and decided to try that first.  Replacing the sockets looked like a lot of work to me. 

DeoxIT has been recommended to me for cleaning the pins but I have not tried that yet. 

I was rebuilding an SB-220 and life got in the way.  It is waiting for me to get back to it. 

73,

Brian
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NJ1K
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Posts: 3




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« Reply #35 on: February 27, 2014, 05:35:46 PM »

When I did my rebuild, I found the pin clips were pitted due to arcing.  I cleaned the clips with a .22 caliber gun cleaning brush.  Then degreased with "BrakeKlean".  Still working good...
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G3RZP
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Posts: 1284




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« Reply #36 on: February 28, 2014, 12:45:29 AM »

Goddards 'Silver Dip' applied with a cotton bud will clean the silver plating. There's a similar product in available in the US, meant for cleaning the family silver.
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W8KR
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Posts: 28




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« Reply #37 on: February 28, 2014, 12:54:53 PM »

G3RZP... Now, why didn't I think of that? We have silver polish in the cupboard.

Thanks and 73,

Jack W8KR
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W8KR
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Posts: 28




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« Reply #38 on: March 03, 2014, 06:58:45 PM »

W8JI and all... I have decided to move ahead with a rebuild of the filament circuit of the Henry, converting it to a parallel circuit from its present series circuit.  W8JI's arguments are compelling for doing this and I believe it's definitely the right thing to do.

With the assistance of you all, I have probably identified the issues that were causing the filament problems described earlier in this thread.  However, I believe it is better now to eliminate Henry's engineering mistakes, rather than putting patches on a faulty circuit.

I'm looking forward to an enjoyable project.  My thanks to all of you.

Jack, W8KR, in Minneapolis
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G3RZP
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Posts: 1284




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« Reply #39 on: March 04, 2014, 12:42:24 AM »

Jack,

My suspicion is that Henry, like Marconi in the UK, used series filaments and a balancing lead to get around providing 28 amp wiring - and maybe a 28 amp filament choke. Fine while everything is tight and it works, and a bitch when it doesn't. I cheated with seal cooling and put a muffin fan blowing directly on each tube base - two fans. Then a big fan up top blowing down onto the tubes with plate connectors that had a horizontal copper disc with holes in it directly in the air flow to keep the plate seals cool. Never had any problem with the sockets after that! OK, that was with 4-250s and 4-400s but the principle is the same for 3-500Z, which has the same filament.

good luck with the project

73

Peter G3RZP
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W8KR
Member

Posts: 28




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« Reply #40 on: March 04, 2014, 12:22:05 PM »

G3RZP... Peter, that's interesting about the wiring and filament choke.  One of the things that puzzled me a bit as I dug into this amp is what appears to be a light-duty filament choke, wound on a circular toroid.  My plans already included replacing that one with a choke I would consider to be more suited for a 2KW PEP amplifier.  That was a guess on my part but probably not too far off, based on your comment.  For the rest of the filament wiring, including the feed from the transformer, what gauge wire would you consider to be suitable for 28A?

I'm going to take Tom, W8JI's suggestion of eliminating the Jones plug in the filament line, so I will have a fairly long filament line coming from the power supply below.

By the way, we have Goddard's silver polish in our cupboard, so it's sold in the States  Smiley
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KL0S
Member

Posts: 149




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« Reply #41 on: March 04, 2014, 02:14:22 PM »

Have to add my thanks to N7BMW's suggestion about replacing the filament pin clip. Had the second instance of solder flow on the same pin but didn't realize the issue was the 3-500Z socket in my venerable L-4B. Actually replaced the tubes a year or so ago with RF Parts bulbs and yesterday one of the tubes wouldn't light...at least I knew what it was but not how to fix it less replacing the whole socket. Luckily after seeing the note here I checked one of my spare sockets and couldn't believe how easy it was to remove the clip. Went back into the L-4B today and replaced the clip, took all of a minute and the difference in closure between the bad and good clip was substantial. I did have to reflow the filament pin and added a bit of silver solder to make it look almost as good as all the other pins.

Hopefully this amp I bought in 1979 will be running for another bunch of years...I may have to tune it but the microprocessor will never die in it (although the one in my head might!).   Wink

Thanks again!

73 - Dino KL0S
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W8KR
Member

Posts: 28




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« Reply #42 on: March 04, 2014, 02:37:53 PM »

Dino... Ain't that a great fix?  This forum is good!
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G3RZP
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Posts: 1284




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« Reply #43 on: March 05, 2014, 12:27:03 AM »

Jack,

I guess the first question is what the transformer voltage is when loaded, because that affects how much voltage drop you can stand. Although cable ratings usually allow over 2000 Amps/square inch (depending on whether or not they are in ducts or free air), I figure that you probably need #10 or maybe #8 depending on the voltage drop you get. If you don't have a 28 Amp filament choke and are going to wind one on a ferrite rod, consider winding it quadrifilar with thinner wire so that you can parallel two winding to get the resistance down and current carrying capacity up.
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W8KR
Member

Posts: 28




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« Reply #44 on: March 19, 2014, 04:41:40 PM »

I'm now well along on re-wiring the filaments in my Henry 2-K to a conventional parallel circuit.  I have mounted a new 5 volt transformer and a new filament choke (both of which I acquired through W8JI) and am almost finished with all the bypassing etc.  But I have a question about the bias circuit that I need to resolve:

It would appear that the Henry bias circuit could be left intact, with the bias being applied to the filaments, with a connection back to the center tap of the filament transformer.  HOWEVER, the Henry bias circuit has a voltage equalizing choke (L7) in it, which is a remnant of the series filament circuit that I am replacing and I'm wondering whether I should eliminate that choke?

If anyone could help by looking at the Henry bias circuit with me, I would appreciate it very much.  I've been comparing it to the bias circuit in a very well done parallel 3-500 circuit by W4NFR, which I found on line.  This circuit is different enough that it's causing me some concern about leaving the Henry circuit the way it is.  Specifically, the circuits appear to be "mirror images" of each other, with the zeners pointing in opposite directions, which is very confusing.  I can forward both the Henry and W4NFR circuits to anyone who would be willing to take a look for me.  My e-mail address is jack@falkerinvestments.com .

Thanks,

Jack W8KR

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