[markmokris]

I just finished another restoration on a Model 89 cathedral with the 36 autodyne. I know I have probably beat the oscillator tickler coil thing to death. But this time I got it to work first time. Maybe this posting will help someone in the future.

27 turns starting from pin 1 ending on pin 2, turning clockwise looking from the bottom of the coil form, using #38 wire. Pin 1 is the first one to the right of the mounting clip looking from the bottom. Worked perfectly and oscillates across the entire band.

In the past, I tried #34 and #36. I know people will say that the wire size is not critical for a ticker coil, but only, only after I went to #38 wire did I get it to work. With this number of turns, and the very thin #38 wire, the resistance measured about 5 ohms, which is very close to what it says on the schematic. I took this as a good sign.

When I brought it up, it squealed like the dickens. But the tube shields were missing. I found a tube shield for the the 75 tube, and that fixed that.

Mark K8KZ

[mikethedruid]

Congratulations, and thanks for the information. Always good to learn from others' experiences.

[Steve Davis]

One more thing, it is always a good idea to bake the coil form at 200 degrees for about 30 minutes. 

Steve  

[Hugh C]

Mark,
What do you recommend I use as an insulator between the two coils? I'm talking about the tickler coil being wound on top of the other coil. From what I've read there's a lot of differences of opinion on what material should be used.

I'm just starting an 89. Do you have any advice on the antenna call?

[klondike98]

Hugh, Welcome to the Phorum!


I edited the two posts you made to combine them into the one you see here.

[markmokris]

What do you recommend I use as an insulator between the two coils?

For an insulator, I just used scotch frosted tape. I lay in on backwards with the sticky side out. This holds the wire in place as I wrap each turn. In order to hold the tape in place, I tape it down with some tiny pieces of additional tape around the perimeter.

Mark K8KZ

[RadioDR401]

Mark, do you cover or coat the tape and tickler coil with anything?  I was concerned about the edges of the sticky tape attracting dirt or metal filings.

[markmokris]

HI Dave,

No I haven't been doing that. I understand your concern, but I haven't found it to be a problem. Ron has suggested spraying the finished coil with clear lacquer. That would negate the stickiness, but I have not resorted to that.

Mark K8KZ

[RadioDR401]

Ok so I gave your method a try and it came out pretty good.  I used some polyimide tape that I found on Amazon that has really good dielectric and temperature specs.  I used 27 turns of #38 like you suggested and I'll be testing it soon.

[markmokris]

Wow that looks great Dave!

Mark K8KZ