On Sun, 21 Sep 2008 12:52:35 -0700 (PDT), charrid
wrote:

On Sep 21, 5:11*am, Jeff Liebermann wrote:
On Sat, 20 Sep 2008 20:02:57 -0700, Jeff Liebermann
wrote:

Free manual for the Eico 710:
http://bama.edebris.com/manuals/eico/710/
I'm too lazy to find a DejaVu decompressor, but I expect there are
some instructions and diagrams of the coils in the manual.

Jeff, thanks very much for your suggestions and links. I have actually
already downloaded BAMA manual (Dejavu plugin works great on IrfanView
4.20, saves as pdf)

Duh. I use Irfanview heavily, but have never bothered to download the
DejaVu plugin. Thanks.

and I will get to work calculating the approximate
inductances. The variable C is the only component they don't show the
value for, but I'll take a guess, wind a coil and listen for the
signal.

That will work as long as you don't accidentally land on a
sub-harmonic. Methinks a frequency counter might be more useful than
tuning around the bands looking for the signal.

If you have a capitance meter or bridge, it might be possible to
measure the value of the tuning capacitor.

Then with some trial and error I can probably come up with a
couple of coils for the ranges I am interested in. I know the scale
won't be accurate, but in this day of digital readouts it's not
important.

Chuckle. A few months ago, I won a used HP something universal
counter on eBay because I wanted the extra digits of resolution.
However, that was for period and event counting, not frequency.

I am fascinated with the number of GDO's shown on N4XY's site - I
remember seeing just Heath, Eico and an old Mullen.

Search Google for "base dip oscillator" and "gate dip oscillator".
There are a few designers that couldn't find the grid pin on the
semiconductor devices. My Heathkit HD-1250 calls it a "solid-state
dip meter".

I don't know if this will help, but the HD-1250 looks very much like
the Eico (other than the tube versus the xistor). Here's a table of
coil values for it assembled from various parts of the manual:

MHZ uH
L1 1.6 - 3.4 171 red
L2 3.2 - 6.6 41.1 orn
L3 6.3 - 13 10.2 yel
L4 12.5 - 26 2.62 grn
L5 25 - 51 0.72 blu
L6 48 - 100 0.196 vio
L7 100 - 250 ???? brn

As usual, no value on the tuning capacitor in the manual, but it can
be calculated from the above data.

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