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Author Topic: MFJ 203 dip meter - Missed Coupling Coils  (Read 1569 times)
LU6FAE
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Posts: 11




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« on: May 25, 2013, 06:22:39 AM »

Hello Sirs,

I would need your help/advices on this subject. I bought a MFJ 203 dip meter and it has no coupling coils. I know from user manual description the coupling coil isn`t a part of resonant circuit but I would need to build a coupling coil to use this piece of equipment.
Could you please comment how to build the missed coupling coil? Ø, wire size, turns or any important dimensions. Any advice is welcome.

Thanks !

Aldo Amprimo
LU6FAE
Rosario Argentina
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K8AXW
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Posts: 3599




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« Reply #1 on: May 25, 2013, 08:24:27 PM »

Aldo:  I would make two suggestions:

1 - Send this same email to MFJ and see what they tell you.  I'm confident they will help you.

2 - In the meantime, I would take some ordinary enameled wire and wind a small coil on a pencil, maybe 2 or 4 turns, any size wire that will remain rigid, scrape the enamel off the ends of the wire and connect the coil to the 203 and try it out.

You might have to use several turns of a finer wire wound on some kind of insulator.

This might turn in a lesson in experimenting before you get your answer.  I think the bottom line is any coil that will give you the coupling you need.
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KE3WD
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Posts: 5694




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« Reply #2 on: May 26, 2013, 08:07:11 AM »

The 203 is a Band Switched dip meter. 

It does not need resonant coils, just a "coupling coil" attached to its RCA jack. 

Nothing special about that, no ferrite needed, this coil can be as simple as a few turns of hookup wire wrapped around a plastic pill bottle, or even an open air coil wrapped with tape. 

A few feet of coax between coil and plug can help in placing the coil near the circuit under test, or in some cases, the coil itself soldered directly to an RCA plug and simply holding the entire meter near the circuit will afford enough coupling. 

If you don't have the User Manual, try contacting MFJ for a copy.  I couldn't find a .pdf manual published online at their site just now, that does not mean they don't have one, sometimes when I do an email inquiry for certain MFJ manuals, they graciously append it to the answering email. 


73

73
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LU6FAE
Member

Posts: 11




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« Reply #3 on: May 26, 2013, 10:26:05 AM »

Thanks A & C by your advices.
I built an inductor by 10 turns and a RCA conector. At least I could see a readable dip with a L-C network from an old radio.
I will build new additionals coils  including the coaxial based extension to spread its use.
Very useful instrument.

73'
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