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ADDENDA MODEL
HF 20
To Improve the performance
possible
from the
HF20,
certain parts
values
have been changed
from
the
values given
in
your book.
A
part
has
been added
also
for
this
reason.
Please correct
your
book
as follows before
beginning
the construction.
REPLACEMENT
PARTS
LIST
&
SYMBOL
IDENTIFICATION
LIST
BELOW SCHEMATIC DIAGRAM
OLD
NEW
SYM.
STOCK#
DESCRIPTION
STOCK#
DESCRIPTION
C2
22506
cap.,
disc.,
.Q2mfd,20%
22507
cap.
,
disc.
,2200
mmf,
±10%
C3
20042
cap.,
disc.,
.05mfd
20039
cap., .lmfd,
400V
*C5
22508
cap.
,
3300
mmf
22518
cap.,
2700mmf,
±10%
C9
2251
1
cap.,
disc.
,5000
mmf,
20%
22514
cap.,
disc.,
850 mmf,
±10%
R18
10430
res.,
4.7KQ,
1/2W,
10%
10442
res.
,
1
.5KQ
,
1/2W,
10%(Br, G,R)
ADD
**R49
new
component
10428
res.
,47KQ
,
1/2W,
1
0%(Y,
V,
O)
*
In
row beginning 22508,
strike
out
C5
and change
quantity from
2
to
1
.
Add new
C5
as
a separate
line.
**
R49 should be connected between
the tap
on
pot
RIO and ground
Instead
of the
{umper
previously
used.
Connect
schematic diagram accordingly.
I.E.
1093
t
9
Electronic Instrument
Co.
,
Inc.
,
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