Xref: utzoo sci.electronics:14570 rec.ham-radio:24763
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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics,rec.ham-radio
Subject: Re: Eico dip meter - Help!!
Summary: DIY coils...
Message-ID: <4049@kitty.UUCP>
Date: 24 Sep 90 00:33:50 GMT
References: <3110@vela.acs.oakland.edu>
Organization: Recognition Research Corp., Clarence, NY
Lines: 38

In article <3110@vela.acs.oakland.edu>, swood@vela.acs.oakland.edu ( EVENSONG) writes:
> I just got one of those "deals you can't pass up" at the local flea market
> on a grid dip meter by Eico.  The catch:  no coils.  I got the thing for
> $2 though.

	I guess we all basically get what we pay for. :-)

> I was wondering if anyone might know where I might get some coils, or how I
> may go about making some perhaps?

	I have an EICO Model 710 Grid Dip meter, which is probably what
you have.  I have no manual for it, however.  I will tell you what I know
about the coils, and perhaps other readers can add to it.

	The EICO model 710 uses eight coils labeled "A" to "H" to cover
the frequency range of 0.4 to 250 MHz.  The lower frequency coils have
a tapped winding, while the upper frequency coils do not.  The following
chart tells you all I know:

COIL	FREQUENCY 	TAP	DESCRIPTION OF COIL
"A"	0.4 - 0.7 MHz	yes	lots of turns of Litz wire & tuned slug
"B"	0.7 - 1.38 MHz	yes	lots of turns of Litz wire & tuned slug
"C"	1.38 - 2.9 MHz	yes	lots of turns of Litz wire & tuned slug
"D"	2.9 - 7.5 MHz	no	approximately 30 turns of 28 AWG enamel
"E"	7.5 - 18 MHz	no	approximately 15 turns of 24 AWG enamel
"F"	18 - 42 MHz	no	approximately 6 turns of 20 AWG enamel
"G"	42 - 100 MHz	no	approximately 2 turns of 18 AWG enamel
"H"	100 - 25 MHz	no	1/2 turn U-shaped 0.125" wire loop

	The coil forms for "A" to "G" are all 0.75" plexiglass, with
the coil winding being about 2" from the pins.

	Armed with the above information and some trial and error, you
could probably duplicate the required coils.

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
VOICE: 716/688-1231   {boulder, rutgers, watmath}!ub!kitty!larry
FAX:   716/741-9635                  {utzoo, uunet}!/      \aerion!larry