mikea wrote:
o MFJ-259 antenna analyzer; I like it a lot. It's not perfect, but it
works well enough for my purposes. Bought used.

Do you have the user written manual? It is in German and AFAIK never translated
but a lot of it is pretty obvious anyway. For example the specs to make
your own "grid dip" coils can be figured out, once you understand the metric
wire sizes.


o MFJ-557 code practice oscillator with key. CPO is OK; key is trash.

If this the plastic based one with the bent metal U shaped bracket, it
was in the 1960's the key a lot of novices first learned to use. It can be
adjusted to work (how well is a matter of opionon) and IMHO should be
given to a boy scout or someone else interested in learning morse code.

You may be lucky, they might actually go far enough to come to the same
conclusion and buy a real key. :-)

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or
understanding, as in he has a sub-wikipedia understanding of the situation.
i.e possessing less facts or information than can be found in the Wikipedia.

Geoffrey S. Mendelson wrote in :
mikea wrote:
o MFJ-259 antenna analyzer; I like it a lot. It's not perfect, but it
works well enough for my purposes. Bought used.

Do you have the user written manual? It is in German and AFAIK never translated
but a lot of it is pretty obvious anyway. For example the specs to make
your own "grid dip" coils can be figured out, once you understand the metric
wire sizes.

Ich lese deutch.

o MFJ-557 code practice oscillator with key. CPO is OK; key is trash.

If this the plastic based one with the bent metal U shaped bracket, it
was in the 1960's the key a lot of novices first learned to use. It can be
adjusted to work (how well is a matter of opionon) and IMHO should be
given to a boy scout or someone else interested in learning morse code.

I was damn lucky: when I got my Novice ticket in 1962, my uncle Stu gave me
a Vibroplex J-36 (he used it as a radio op on B-25s in WWII, he told me)
and a J-38 that he also had used. Still have 'em.

You may be lucky, they might actually go far enough to come to the same
conclusion and buy a real key. :-)

Except for the high-end MFJ stuff, they appear to go for the lowest priced
stuff that will get the job done and last for the design lifetime -- which
I think is the warranty period.

--
Answer: two spoonfuls in my cup, please.
Question: how much should I use?

(why top-posting is bad)

mikea wrote:

Ich lese deutch.

Sehr Gut!

Except for the high-end MFJ stuff, they appear to go for the lowest priced
stuff that will get the job done and last for the design lifetime -- which
I think is the warranty period.

I have a tow MFJ tuners I bought circa 1995. One of them arrived with a
loose screw and the other had a pop rivet loosen (recently) on one of
the SO-239's on the back.

Both simple fixes.

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or
understanding, as in he has a sub-wikipedia understanding of the situation.
i.e possessing less facts or information than can be found in the Wikipedia.

In article ,
Geoffrey S. Mendelson wrote:

Do you have the user written manual? It is in German and AFAIK never translated
but a lot of it is pretty obvious anyway. For example the specs to make
your own "grid dip" coils can be figured out, once you understand the metric
wire sizes.

.... but, alas, probably not worth the effort (in my experience, at
least). The MFJ 2x9 with the grid-dip coils is absolutely the least
sensitive and hardest-to-use grid-dip oscillator I've tried.

A few years ago I did a three-way shoot-out between GDOs. The test
tank was a piece of scrap Airdux inductor, with an air-variable
capacitor soldered across the ends.

The MFJ had to have its probe coil shoved right up next to the end of
the coil to get a dip indication. The frequency readout was nice and
precise, but the dip was not terribly deep, and with the probe so
close to the coil I'd be very concerned about the probe "loading" the
tank and pulling it off frequency.

A Heathkit solid-state GDO was rather better, with a sharp dip
available with its probe about a half-inch away from the end of the
inductor.

The best results came from a Measurements 59 GDO - the old firebottle
model with a peanut tube in the sensing head. It got a sharp dip
deflection with the probe 2-3" away from the end of the inductor!
This model is big, clunky, and is probably the gold-standard for GDOs.

I've since picked up a Millen but haven't done a head-to-head
comparison with the others. Based on what I've read, it's probably
somewhere between the Measurements and the Heathkit in sensitivity.

The best approach might be a hybrid... use a good GDO to find the dip
frequency, then hold it near an MFJ 2x9 in frequency-counter mode to
get a precise readout of the frequency. It's a shame there's no
single GDO which has both high sensitivity and a really precise
frequency readout.

Might be a tempting project one of these days... build a lambda-diode
GDO and add a precise frequency counter module to it.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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