SB 620 3395 IF coil info

[Ken Ketner]

Bob N7BH provided this helpful information for the SB 620 I am
attempting to rebuild. With his permission, I forward his info the list
in case someone else can use it.  Ken Ketner


Thu, 5 Apr 2001 13:28:55 EDT
From: N7BH at aol.com
To: ketner at arisbeassociates.com

SB 620 3395 IF coil info
To begin,  I do not know the size of your junkbox so I will assume you
have a
supply of odds and ends.

L1
Unfortunately, I did not count the turns when I wound this inductor so I
will
have to go back and work this out.  You will need a slug tuned coil
form,
hopfully with a base mount similiar to the heath coil form.
The good news is that L1 is just a 350khz  trap and is not essential to
the
operation of the set.  You could leave this one out and probably not
even
notice the difference.  That said, I will still work on the number of
turns
(its quite a few) and I may have to make this one for you as I have an
L1 I
can use to duplicate the inductance.

L2
You will need two T50-2 toroid cores.  Wind  each with 62 turns of #32
enamaled wire.  Each will require 44 inches of wire.  Mount the coils on
a
standard 1/4 inch coil form ( same as L1 but slug not needed) and space
5/8
of an inch apart.  Leave about a 30 degree gap between the beginning and
end
of the winding to reduce stray capacitance.  This takes a bit of time
but not
that hard to do.
I can tell you where to get the cores.  It may even be better for me to
send
them to you.  I can also supply the wire.

L3  is wound on the same type of coil form as L1.  Start the winding 1/2
inch
up from the base of the coil form and make the winding about 7/32 inches
wide.  Wind 9 turns clockwise ( viewed from the top)  Start at lug 1 and
end
the tap at lug 4.  Continue winding  from lug 4 till you reach a total
of 43
turns ( 9 plus 34) and connect the end to lug 3.  I used #34 litz wire
from
and old choke.  Anything close should do.  48 inches of wire is
required.
To preset  L3  turn the slug down tight to the base.  Now turn the slug
up
about  four turns.  If You have a counter, you should read about 4700
khz, if
not adjust for this freq.  This should put the pip about in the center
of the
screen.
--

Ken Ketner
ARS KA5ELD
                Personal Webpage: http://www.wyttynys.net
                Office Webpage: http://www.pragmaticism.net
Email:
        home:   ketner at arisbeassociates.com
        office: b9oky at ttacs.ttu.edu

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