Neat Coil form Idea.

[Ed/KB1HYS]

This is either Hammy-Hambone or really neat.

I was rebuilding an old BC/SW set from the 1940's.  It had the 'green dot' disease, this is where various parts of coils develop bright green copper oxide deposits which usually means the coil has opened up.   I needed to replace a small coil used in the 'wave trap' on this set.  I had tried rewinding the original on the cardboard form but no joy. The old form just wasn't up to the task, and my coil winding did not look so good, more importantly it also didn't work .  The original used Litz wire, a very fine multistrand magnet wire, and I couldn't fit enough regular 30 awg on the form to get into resonance.

  Replacements being hard to find, what to do?   Well my wife sews a lot of stuff... so I 'borrowed' one of her cheap plastic bobbins used for holding the thread under the needle.  Looked to be about the perfect size, and the repair would be under the chassis, invisible, so as long as it worked it would be ok fine.   

Sure enough, after a bit of cut and try to get the frequency adjusted, it works!!  A little bit of epoxy to hold the bobbin to the original solder tab mounts on the trimmer and we're back in business!   

This success got me to thinkin' - stack these guys on a 1/4 inch dowel and you could make up a really nice Pi-wound choke for pennies!     

[WA1GFZ]

necessity is the Frank Zappa of invention

[W3GMS]

Ed,

Hams are great innovators and somehow we always seem to come up with something that works!  Congrats on discovering the bobbin idea and thanks for sharing it. That idea will probably help someone else out down the road.

Speaking of wave-traps, I need to build one for my HR-10 receiver.  The 1680 Khz IF gets clobbered by a BC station operating in the expanded AM band.  Last year when I used the HR-10 with the DX-60 for SKN, it was interesting to hear a Spanish speaking station along with the cluster of CW signals I was trying to copy!     

What set are you restoring?

Joe, W3GMS

[W7TFO]

A regular Singer metal bobbin makes a great common ground point for HB work.  Put a #10 screw through the hole, set it on a 1/4" spacer, and secure it to your chassis.  Put all your ground leads through the little holes around the edge and solder away.

73DG

[KB2WIG]

necessity is the Frank Zappa of invention

http://www.youtube.com/watch?v=y9P2V0_p6vE

[KG6UTS]

A regular Singer metal bobbin makes a great common ground point for HB work.  Put a #10 screw through the hole, set it on a 1/4" spacer, and secure it to your chassis.  Put all your ground leads through the little holes around the edge and solder away.

73DG

That is neat!!!! A great idea for building the chokes....now off to rob Bonnie's Singer. When WA7VOV and I were playing regen receiver we used the 'pill' bottles that hold the pins or sockets for military or Amp connectors as coil forms. Just screw or super glue the lid to the perf board, wind the coil/tickler on the bottle with super glue or coil dope on the windings then stick the bottle back to the lid. It was good because you could pop the bottle/coil form off the base if(when?) you needed to adjust windings.

Thanks for the 'Heads-up'!

73
EdZ KG6UTS
Baja CA

[Ed/KB1HYS]

The set is a Zenith 10S566 console model, does AM BC band, through 18mhz or so in 3 bands.  I found the IF problem... I had rewired the set a long time ago, it never worked right since.  I had checked but missed a cold solder joint, which popped off when I wiggled it.  Then I did a double take on the schematic and found that I had soldered that wire to the wrong terminal point!!  Aaagh.  Any number of reasonable checks (schematic trace, Solder inspection, Voltage check on the tube socket) should have told me what was wrong.  I just assumed I had done a 'good enough' job of checking my work and it must be a bad tube.  Well now I have a spare tube and a decent workng set that looks nice.  I'll post some p0rn when I start reassembling to the case.  I have to admit, she sounds really sweet.  I picked up NGK World Radio from Tokyo this evening.... very nice indeed.

[W7TFO]

Every old radio saved like that is a true treasure, and those that can't be saved should live on as parts in others.

Good job, Ed!

73DG