On Sat, 20 Sep 2008 16:14:21 -0700 (PDT), charrid
wrote:

Would anybody who owns Eico model 710 GDO be willing to supply coil
data (diameter, length, No. of turns, wire diameter) so that I could
duplicate the coils?

Yech, tubes. I have several Heathkit grid dip meters, but no Eico.

This may help:
http://www.qsl.net/n4xy/GDO_EICO.html
The photo shows one coil, which should give you an idea as to the
general size and construction of the coil.

The photo of the Eico 710-A looks very much like one of my Heathkits
(buried somewhere). Do you have a 710 or a 710-A. There's a huge
difference.

I bought the coil-less 710 at the fleamarket and
cannot find the coil set. I am mainly interested in the 2.9-7,5 and
7.5-18 MHz ranges. Or maybe a close-up photo with a ruler laying next
to the coils would be enough.
73, Rich OK8RF

Others have suggested cut-n-try which is probably good enough. As
long as the coil looks roughly like the original, it should work.

However, if you wanna do the math, look at the schematic and figure
out the minimum and maximum capacitance on the variable tuning
capacitor. Be sure to include any trimmers or padding capacitors in
the tuned circuit. You know the lowest and highest frequencies from
the dial. Drag out your abacus and plug the numbers into the usual LC
resonant frequency equation. Solve for a value of L that will be
roughly the same at both the high and low ends of the dial. You
probably won't hit the exact value, but it should be close. Lots of
online calculators for the inductance of solenoid wound coils. No
need for an LRC meter as you can just plug it into the grid dip meter
and count the frequency.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558