Thursday 29 December 2022

Revisted - A further tear down of HF "walkabout" antennas - Comet CHF-412

 I started to strip down the Comet CHF-412 antenna and put it to one side as I didn't want to misplace any thing. Today I striped the coils and measure /counted the turns on the inductors from the PCB

On one side it had the red inductors, I think these could be T37-2 but not sure and a 5pf cap:


 

Top inductor near whip had 32 turns (4.60mH)

Below that the second inductor had 31 turns (4.39mH)

 

The other side had two black inductors and a balun/transformer:

Top inductor near whip had 22 turns (8.45mH)

Below that the second inductor had 23 turns (9.20mH)


 

The balun/transformer has bifilier winding. Gold wire 9 turns: One connected to the inner of BNC and the other to ground. 

The red wire had 12 turns: One connted to antenna and the other two ground. 

As I'm not expert and knowledge of these things I do lack, if it had the same amount of turns I would of said it was a 1:1/isolation. It still could be a 1:1 transformer (maybe someone can enlighten me?).


 



As this arrangement didn't work, I'm now think of what I can do to make it work on one or two bands. For some fun ( and I mean laugh.....)  I'm wondering if I can wind a 49:1 on a very small toroid and use the inductors and whip to create a electrically short endfed half wave or do I use the balun and rewind the new toroids to see if I can get it to match??



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