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Homemade coils for using an MFJ analyzer as a dip meter?



 
 
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  #1  
Old January 28th 06, 07:51 PM posted to rec.radio.amateur.antenna
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Default Homemade coils for using an MFJ analyzer as a dip meter?

I have an MFJ modle 249 (the original with a meter) antenna analyzer. MFJ
sells a kit of two coils to make it into a dip meter.

I would like to use it to measure the resonant fequency of a traps I
am building, but am unable to purchase the coils.

Is there a way to make then on your own?

TIA,

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Vist my 'blog at
http://geoffstechno.livejournal.com/
  #2  
Old January 28th 06, 08:44 PM posted to rec.radio.amateur.antenna
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Default Homemade coils for using an MFJ analyzer as a dip meter?

"Geoffrey S. Mendelson" wrote in message
...
I have an MFJ modle 249 (the original with a meter) antenna analyzer. MFJ
sells a kit of two coils to make it into a dip meter.

I would like to use it to measure the resonant fequency of a traps I
am building, but am unable to purchase the coils.

Is there a way to make then on your own?

TIA,

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice:
1-215-821-1838
Vist my 'blog at
http://geoffstechno.livejournal.com/



I think I have a spare set of coils for the MFJ-201 dip meter, missing only
the UHF coil. I don't know if the coils are the same for the 247, but if
you can verify that they are the same, maybe we can make a deal.

Email me if you're interested
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in
the address)

Never take a laxative and a sleeping pill at the same time!!


  #3  
Old January 29th 06, 05:06 AM posted to rec.radio.amateur.antenna
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Default Homemade coils for using an MFJ analyzer as a dip meter?

Geoffrey S. Mendelson wrote:

I have an MFJ modle 249 (the original with a meter) antenna analyzer.
MFJ sells a kit of two coils to make it into a dip meter.

I would like to use it to measure the resonant fequency of a traps I
am building, but am unable to purchase the coils.

Is there a way to make then on your own?

TIA,

Geoff.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Don't bother. I have one and it's a very poor dip meter. Get a Heathkit
or Eico or Millen instead. You'll be much happier.

73, Bill W6WRT
  #4  
Old January 29th 06, 06:50 AM posted to rec.radio.amateur.antenna
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Posts: n/a
Default Homemade coils for using an MFJ analyzer as a dip meter?

I have an MFJ modle 249 (the original with a meter) antenna analyzer.
MFJ sells a kit of two coils to make it into a dip meter.

I would like to use it to measure the resonant fequency of a traps I
am building, but am unable to purchase the coils.

Is there a way to make then on your own?


Don't bother. I have one and it's a very poor dip meter. Get a Heathkit
or Eico or Millen instead. You'll be much happier.


The MFJ 269 with the dip-meter coils, is probably the least-sensitive
and least-usable dipmeter I've tried to date. It really isn't good
for very much at all.

I don't think the coil construction is terribly critical, though,
since the coil inductance is not being used as part of the oscillator
tuned circuit. The MFJ uses only two coils to cover a wide range of
frequencies, rather than the half-dozen or so coils used by real
tank-circuit dippers.

You can try simply winding a few turns of hookup wire on a convenient
tubular form, hooked up to an RCA or BNC or PL-259 glued to the end of
the form, and see if you can get an adequate dipping for your
purposes.

The higher-frequency MFJ coil seems to be about 4 or 5 turns of wire -
length is about 1/2" and diameter is somewhere around 3/8". The
lower-frequency coil is somewhere around 12-14 turns of wire,
close-wound on a 1/2"-diameter plastic form.

As dippers go, the Heathkit HD-1250 solid-state model (it's a
dual-gate-MOSFET-based gate-dipper rather than a grid-dipper) is
better than the MFJ. It's not great, but it's probably adequate for
most purposes.

Haven't used a Millen but I've heard that it's better yet. Haven't
used an Eico, or one of the B&W model 600 acorn-tube-based grid
dippers.

The Measurements/Boonton Megacycle Meter is the ne plus ultra of
dippers, as far as I know. It's big and perhaps a trifle clumsy, but
it has a strong oscillator which *really* dips nicely with even very
loose coupling to the circuit being measured. If you ever run across
one, grab it.

For comparison: when testing an air-core inductor in parallel with an
air-variable cap, I could barely get a dip reading at all with my MFJ
and either of its coils. The coil had to be poked right up into the
inductor and into contact with its windings to create enough coupling
for a dip... and of course this tends to de-tune the coil and makes
the measurement less accurate.

A Heathkit HD-1250 would get a usable dip with its coil as far as an
inch away from the inductor.

A Boonton got a dip three or four inches away.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
  #5  
Old January 29th 06, 08:41 AM posted to rec.radio.amateur.antenna
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Default Homemade coils for using an MFJ analyzer as a dip meter?

Bill Turner wrote:

Don't bother. I have one and it's a very poor dip meter. Get a Heathkit
or Eico or Millen instead. You'll be much happier.


Thanks for the information. The whole purpose is to avoid paying 180 UKP
for a multiband trap antenna. I have access to coax and plastic pipe,
so I was hoping to make the traps myself.

As for buying an Eico or Millen, I doubt that there is one in the entire
country yet alone for sale, :-(

73,

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Vist my 'blog at
http://geoffstechno.livejournal.com/
  #6  
Old January 29th 06, 08:51 AM posted to rec.radio.amateur.antenna
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Posts: n/a
Default Homemade coils for using an MFJ analyzer as a dip meter?

Dave Platt wrote:
The MFJ 269 with the dip-meter coils, is probably the least-sensitive
and least-usable dipmeter I've tried to date. It really isn't good
for very much at all.


Thanks,

Hopefully it won't have to be very good. I need it to make a trap antenna,
I found what I want for 180 UKP (plus shipping and taxes), but simply can't
afford it. In fact, buying the $20 coils is a stretch at this time.

I have plenty of coax and plastic pipe is easily available.

I don't think the coil construction is terribly critical, though,
since the coil inductance is not being used as part of the oscillator
tuned circuit. The MFJ uses only two coils to cover a wide range of
frequencies, rather than the half-dozen or so coils used by real
tank-circuit dippers.


It did seem awfuly cheap, the same range in their dip meter was covered
by at least five coils.

You can try simply winding a few turns of hookup wire on a convenient
tubular form, hooked up to an RCA or BNC or PL-259 glued to the end of
the form, and see if you can get an adequate dipping for your
purposes.


Ok, thanks, it may be exactly what I need.


The higher-frequency MFJ coil seems to be about 4 or 5 turns of wire -
length is about 1/2" and diameter is somewhere around 3/8". The
lower-frequency coil is somewhere around 12-14 turns of wire,
close-wound on a 1/2"-diameter plastic form.


This sounds good to me, I should be able to duplicate that.

As dippers go, the Heathkit HD-1250 solid-state model (it's a
dual-gate-MOSFET-based gate-dipper rather than a grid-dipper) is
better than the MFJ. It's not great, but it's probably adequate for
most purposes.


Heathkit? What's a heathkit? I have not seen one in the nine years I've
been here. A friend supposedly has a heathkit HF rig in boxes from when he
moved here, 25 years ago, I'm sure he hasn't even turned them on in
at least five years.


The Measurements/Boonton Megacycle Meter is the ne plus ultra of
dippers, as far as I know. It's big and perhaps a trifle clumsy, but
it has a strong oscillator which *really* dips nicely with even very
loose coupling to the circuit being measured. If you ever run across
one, grab it.


In a country there are no hamfest, no swap meets, no ham radio stores,
and you need to get permission from the Ministry of Communication to
buy a new rig (pro-forma, but it must be added to your license),
I expect that I'll never run across one, even if I hunt it down. :-(


73,

Geoff.
--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Vist my 'blog at
http://geoffstechno.livejournal.com/
  #7  
Old January 29th 06, 11:19 AM posted to rec.radio.amateur.antenna
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Default Homemade coils for using an MFJ analyzer as a dip meter?

Hi Geoff

here manual with description for homemade coils

http://www.darc.de/distrikte/f/27/MF...andbuch1v4.pdf

73 Henk



  #8  
Old January 29th 06, 11:19 AM posted to rec.radio.amateur.antenna
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Posts: n/a
Default Homemade coils for using an MFJ analyzer as a dip meter?

Hi Geoff

here manual with description for homemade coils

http://www.darc.de/distrikte/f/27/MF...andbuch1v4.pdf

73 Henk




  #9  
Old January 29th 06, 12:27 PM posted to rec.radio.amateur.antenna
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Default Homemade coils for using an MFJ analyzer as a dip meter?

Geoffrey S. Mendelson wrote:

As for buying an Eico or Millen, I doubt that there is one in the
entire country yet alone for sale, :-(

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Try eBay.

73, Bill W6WRT
  #10  
Old January 29th 06, 12:30 PM posted to rec.radio.amateur.antenna
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Default Homemade coils for using an MFJ analyzer as a dip meter?

on4ahf wrote:
Hi Geoff

here manual with description for homemade coils

http://www.darc.de/distrikte/f/27/MF...andbuch1v4.pdf


Thank you, it's exactly what I needed. I am having trouble with one point.

The wire type in the table is CuL and CuAg. Obviously CuL some sort of
copper wire, with the CuAg, being copper and silver (silver plated copper?).

What exactly is CuL wire? Is it critical that I use it what ever it is?
Can I use plastic covered copper wire?

For the high freqency coils I can easily get 2.0mm stiff copper
wire for use in electrical conduit. It comes with some sort of insulation,
probably PVC. Can I use it, and if I do, should I remove the insulation?

Thanks in advance,

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Vist my 'blog at
http://geoffstechno.livejournal.com/
 




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