Boredom got the best of me: AA5 hum and loop antenna

[Kevin Kuehn]

I think these are the intended connections for the antenna as pictured below. The outside antenna wire and ground form a single turn around the perimeter of the internal spiral loop. Internal loop connects between AVC line and the grid of the 12BE6. The outside antenna ground should be left disconnected or returned to an earth ground, but not the AC chassis ground, unless you don't mind having a shock hazard.

[JohnCT]

Originally Posted by Kevin Kuehn

I think these are the intended connections for the antenna as pictured below. The outside antenna wire and ground form a single turn around the perimeter of the internal spiral loop. Internal loop connects between AVC line and the grid of the 12BE6. The outside antenna ground should be left disconnected or returned to an earth ground, but not the AC chassis ground, unless you don't mind having a shock hazard.

Yeah, that's unlike what i have:



In this radio, there's only three connections on the antenna board, the two for the loop and the third (blue wire attached) which is not connected to the loop in any way. You can also see that the third runs inside the loop, and is pinned into the fiberboard.

It can be connected to an antenna, to an earth ground, but not both.

John

[old_coot88]

Looks like pure capacitive coupling from the external antenna is what's intended.

[Kevin Kuehn]

Thanks for posting the picture. Obviously they made variations over a period. I'm now done beating the subject to death. Until next time

[Kevin Kuehn]

Originally Posted by old_coot88

Looks like pure capacitive coupling from the external antenna is what's intended.

What do you suppose is the significance of the little right angle bend at the end?

[edit]I thought there was a bend on the left end, but after enlarging the photo it seems it's only a mark on the fiberboard. Now I'm really curious how those were manufactured.

[JohnCT]

Originally Posted by Kevin Kuehn

Thanks for posting the picture. Obviously they made variations over a period. I'm now done beating the subject to death. Until next time

I should have posted the picture when I first asked the question. But this one must be out of the ordinary. In any case, I do appreciate the help from you, OC88, Max, etc.

Originally Posted by Kevin Kuehn

What do you suppose is the significance of the little right angle bend at the end?

[edit]I thought there was a bend on the left end, but after enlarging the photo it seems it's only a mark on the fiberboard.

Yep. It looks like the end was stamped/pinned/guillotined into the fiberboard to keep it from wandering loose. The mark is just the divot.

John