I have an old Heath HD-1250, which is a solid state equivalent, and I have
never been convinced that it works well. Seems like the dips are vague,
unless coupling to the circuit is awfully tight.

I have one of those (eBay purchase as of a couple of years ago) and I
agree with your assessment. The oscillator is fairly weak, I think,
and you need very tight coupling to get a significant dip... and of
course the tight coupling tends to perturb the circuit being measured.

The dip-meter attachment for the MJF antenna analyzer isn't much better.

I've heard that the James Millen dipmeter is somewhat better, but not
great.

If you can manage to get your hands on a Measurements Inc. ("Boonton")
tube-powered grid dip meter, I think you'll find that it's another
bushel of peas entirely. It's big, a bit clumsy (the oscillator head
alone is almost half the size of the HD-1250, plus a desktop power
supply and meter), and it may need to have its tubes replaced, but WOW
does it ever dip! I used a test coil and cap combination to test it -
with the HD-1250 the dipper coil had to be held inside the test coil
to couple well enough, while with the Boonton I got a very usable dip
with the dipper coil 3-4" away on axis!

B&W also made a grid dip meter, with an acorn-tube oscillator (similar
to the one used in the Boonton) which might be worth a look.

Keep your eyes peeled for one of these old firebottle-powered GDMs at
local hamfests!

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