Heathkit HD-1250 User manual

HEATHKIT
MANUAL
for the
SOLID-STATE
DIP METER
Model HD-1250
COMPANY •BENTON HARBOR. MICHIGAN

YOUR HEATHKIT 90 DAY LIMITED WARRANTY
If you (ire not satisfied with our service -warranty or otherwise -or with
our products, write directly to our Director of Customer Services. Heath
Company. Benton Harbor. Michigan 49022. Ha will make certain your
problems receive immediate, personal attention.
Our attorney, who happens to bo quite akitbuilder himsolf. insists that
we describe our warranty using all the necessary legal phrases in order
to comply with the new warranty regulations. Kine. Here they are
For aperiod of ninety (901 days after purchase, Heath Company will
replace or repair (roe of charge any parts that are defective either in
materials or workmanship. You can obtain parts directly from Heath
Company by writing us at the address below or by telephoning us at
|(i 16) 0/12-3571. And we'll pay shipping charges to get those parts to you
—anywhere in the world.
We warrant that during the first ninety |90) days after purchase, our
product*, when correctly assembled, calibrated, adjusted and used in
accordance with our printed instructions, will meet published specifi-
cations.
If adefective part or error In dosign has caused your Heathkit product to
malfunction during the warranty period through no fault of yours, we
will service it free upon proof of purchase and delivery at your expense
to the Heath factory, any Heathkit Electronic Center (units of Schlum-
berger Products Corporation!, or any of our authorized overseas dis-
tributors.
You will receive free consultation on any problem you might encounter
in the assembly or use of your Heathkit product. Just drop us a line or
give us acall. Sorry, we cannot accept collect calls.
Our warranty does not cover and we are not responsible for damage
caused by the use of corrosive solder, defective tools, incorrect assem-
bly, misuse, fire, or by unauthorized modifications to or uses of our
products for purposes other than as advertised. Our warranty does not
include reimbursement for customer assembly or sot-up time.
This warranty covers only Heathkit products and is not extended to
allied equipment or components used in conjunction with our pro-
ducts. Weare not responsible for incidental or consequential damages.
Some states do not allow the exclusion or limitation of incidental or
consequential damages, so the above limitation or exclusion may not
apply to you. This warranty gives you specific legal rights, and you may
also have other rights which vary from state to stale.
HEATH COMPANY
BENTON HARBOR, Ml 49022
HEATH COMPANY PHONE DIRECTORY
The following telephone numbers are direct lines to the departments listed:
Kit orders and delivery information (616) 962-341
1
Credit [phone]
Replacement Parts [phone]
Technical Assistance Phone Numbers
8:00 AM. to 12 P.M. and 1:00 P.M. to 4:30 P.M.. EST. Weekdays Only
HC. Audio, and Electronic Organs [phone]
Amateur Radio [phone]
Teat Equipment. Weather Instruments and
Home Clocks [phone]
Television [phone]
Aircraft, Marine. Security, Scanners, Automotive.
Appliances and General Products [phone]
Computers [phone]
Prices and specifications subject to change without notice.

Heathkit® Manual
for the
SOLID-STATE
DIP METER
Model HD-1250
595-1651-04
HEATH COMPANY
BENTON HARBOR. MICHIGAN 49022 Copyright ©W7S
Heath Company

Page 2
TABLE OF CONTENTS
Introduction 2
Parts List 3
Step-by-Step Assembly
Assembly Notes 13
Detector Circuit Board 14
Oscillator Circuit Board 17
Chassis 20
Top Panel Assembly 26
Initial Test 29
Oscillator Installation 31
Side Panel Assembly 34
Final Adjustment 35
Trimmer Adjustment 36
Calibration 37
Final Assembly 3g
Operation 42
Applications 47
In Case of Difficulty 53
Troubleshooting Chart gO
Specifications 62
Circuit Description 63
Circuit Board X-Ray Views ! . ! 64
Circuit Board Voltage Charts 9&
Diode-Transistor Identification Chart 66
Schematic. .(fold-out from page) 67
Warranty Inside front cover
Customer Service Inside rear cover
INTRODUCTION
Your Heathkit Solid-State Dip Meter can be used to determine the approximate
resonant or operating frequency of either energized or de-energized circuits in
the frequency range between 1.6 and 250 MHz. In the oscillation or injection
mode, you may use the Dip Meter to determine the resonant frequency of tuned
circuits or as avariable signal source to align receivers. In the absorption mode, it
will locate sources and frequencies of RF energy. It is also valuable for locating
sources of parasitic oscillations and harmonics.
You can select any of the seven frequency ranges by using the appropriate
plug-in coil. Its size and battery-powered circuit make the Dip Meter completely
portable. Two circuit boards are used to provide compactness and ease of
assembly. Two transistors and two hot-carrier diodes are used in the
all-solid-state circuit. To help in both transportation and storage, amolded
carrying case is provided for your convenience.
Refer to the "Kit Builders Guide" for information on tools, wiring, soldering,
resistors, and capacitors.

Page 3
PARTS LIST
Check each part against the following list. Make acheck (\/) in the space
provided as you identify each part. Any part that is packed in an individual
envelope with the part number on it should be placed back in the envelope after
you identify it until it is called for in astep. Do not discard any packing
materials until all parts are accounted for.
Each circuit part in this kit has its own "Circuit Component Number" (R1.C11.
D21, etc.). This is aspecific number for only that one part. The purpose of these
numbers is to help you easily identify the same part in each section of the
Manual. These numbers will appear:
-In the Parts List.
-At the beginning of each step where acomponent is installed.
-In some illustrations.
-In the sections at the rear of the Manual.
To order areplacement part, always include the PART NUMBER. Use the Parts
Order Form furnished with the kit. If one is not available, see "Replacement
Parts" inside the rear cover of this Manual. Your Warranty is located inside the
front cover. For pricing information, refer to the separate "Heath Parts Price
List."
(3TY. DESCRIPTION PART CIRCUIT
No. Component
No.
RESISTORS, 1/4-Watt, 5% Tolerance
NOTE: 5% tolerance resistors have afourth color band of gold.
()127 n(red-violet- 1-96-12 R12
black)
( ) 2330 n(orange- 1-92-12 R24, R25
orange-brown)
()11500 A(brown- 1-71-12 R14
green-red)

Page 4
QTY. DESCRIPTION PART
No.
Resistors (cont'd.)
()22200 n(red-red 1-72-12
red)
( ) 14700 fi (yellow- 1-76-12
violet-red)
( ) 110 kfl (brown- 1-80-12
black-orange)
()227 kfi(red- 1-81-12
violet-orange)
()147 kfi (yellow- 1-83-12
violet-orange)
()2100 kfi (brown- 1-84-12
black-yellow)
CAPACITORS
()247 pF mica
()15pFdisc
()4.001 ixF disc
20- 101
21- 157
21-140
()1.01 mF disc 21-176
()3.01 fiF ceramic (small) 21-185
NOTE: May be
marked "103.
"
*1Tuning capacitor 26-146
CIRCUIT
Component
No.
R26, R27
R11
R15
R16, R21
R22
R13, R23
C11.C12
C13
C15. C23, C24
C25
C26
C14. C22, C27
C21A, C21B,
C21C

QTY. DESCRIPTION PART
No.
DIODES-TRANSISTORS
<)2FH1 100 diode
CIRCUIT
Component
No.
LUILb
()11.6-3.4 MHz coil 40-1689 LI
(red)
.(, "it -^^*>
( ) 13.2-6.6 MHz coil 40-1690 L2
(orange)
( ) 16.3-13 MHz coil 40-1691 L3
(yellow)
()112.5-26 MHz coil 40-1692 L4
(green)
( ) 125-51 MHz coil 40-1693 L5
(blue)
()148-100 MHz coil 40-1694 L6 2%T
(violet)
()1100-250 MHz coil 40-1695 L7
(brown)
56-87 D21, D22
NOTE: Transistors may be marked for identification in any of the
following four ways:
1. Part number.
2. Type number.
3. Part number and type number.
4. Part number with atype number other than the one listed.
Page 5

Page 6
QTY. DESCRIPTION PART
No.
CIRCUIT
Component No.
iransisxors icont a.)
()140673
()1MRF502
METAL PARTS
()1Chassis
()1Right side panel
()1Left side panel
{)1Top panel
417-274
417-290
200-691
203-1608-2
203-1609-2
203-1621-2
Q21
Q11

QTY. DESCRIPTION PART CIRCUIT
No. Component
No.
WIRE-BRAID
2-1/2" Bare wire 340-2
3" Orange wire 344-93
3" Yellow wire 344-94
3" Green wire iaaac
5" Blue wire 344-96
8" Braid 345-1
HARDWARE
()66-32x3/16" screw 250-138
()86-32 x3/8" black 250-381
screw
i)1#6 self-tapping 250-106
screw
<)18-32x1/4" set 250-43
screw
()26-32 nut 252-3
()4Spring nut 252-22
()2Control nut 252-39
()2#6 lockwasher 254-25
0V4%3/J 1(INCHES) 2
O*1(CM) 23460780 10

Page 8
QTY. DESCRIPTION PART
No.
Hardware (cont'd.)
()3#6 flat washer 253-127
()1Fiber washer 253-62
()1Control solder lug 259-12
PLASTIC PARTS
()42" foam gasket (1 extra) 73-64
15-3/4" x7-3/8" foam 75-709
pad
15" thin foam tape 73-92
2Shoulder washer 75-18
11-7/8" x5-1/2" fiber 75-103
insulator
4Foot 261-29
1Hairline grid 414-32
1Pushbutton knob 462-353
1Small round knob 462-395
1Large round knob 462-256

Page 10
QTY. DESCRIPTION PART
No.
CIRCUIT
Component No.
Miscellaneous (cont'd.)
( ) 1Meter
( ) 1Battery connector
407-705
432-798
()1Coil socket 434-107 J1
()
()
()
()
1Phone jack
1Phone plug
1Ferrite bead
1Nut starter
436-16
438-26
475-10
490-5
J2
FB
()Solder

QTY. DESCRIPTION PART
No.
CIRCUIT
Component No.
PRINTED MATERIAL
NOTE: Be sure you refer to the numbers on the blue and white label in any
communications you may have about this kit with Heath Company. You may
wish to copy the model and series numbers from the label supplied in this
sample for future convenience.
1Blue and white label 391-34
1Dial label 390-1067
1"Heathkit" label 390-1069
1Parts Order Form 597-260
1Kit Builders Guide 597-308
1Manual (See front cover
for part number.)
Page 11
HEATHKIT
MODE L
HD-1250
SOLID STATE
DIP METER

BATTERY
The following battery should be purchased at this time for
use in your kit:
One 9-volt transistor battery. NEDA #1604.

Page 13
STEP-BY-STEP ASSEMBLY
ASSEMBLY NOTES
1.Before you start to assemble this kit, review the wiring, and soldering
information in the "Kit Builders Guide." Also be sure to read each step
all the way through before performing that step.
2. Due to the small foil area around some circuit board holes and the small
areas between foils, you must use the utmost care to prevent solder bridges
between adjacent foil areas. Use only aminimum amount of solder and do
not heat components excessively with the soldering iron. It is also very
important that you keep your soldering iron tip clean and well tinned.
Diodes, transistors, etc., can be damaged if subjected to an excessive
amount of heat.
3. Resistors will be called out by their resistance value in nor kJ2 (kilohms)
and color code.
4. Capacitors will be called out by their capacitance value (in pF or /jF) and
type (disc, mica, or ceramic).
5. Because the oscillator circuit board is small and has atendency to move
when being soldered, it is agood idea to hold it in some manner. Asimple
jig made up of asmall board and apincher clothspin, as shown in Figure
A, works very well for this purpose. Asmall vise can also be used.
BOARD
Figure A
SAFETY WARNING: Avoid eye injury when you cut off excess leads. Hold the
leads so they cannot fly toward your eyes.

Page 14
anasa
Position the detector circuit board as
shown in the Pictorial. Then proceed with
the following steps. As you install each
component in this column, solder its leads
to the foil and cut off the excess lead
lengths.
NOTE: When you install diodes, as in the
following steps, be sure you position the
banded end of each diode as it is shown on
the circuit board.
BANDED
END
t)D22. FH1 100 diode (#56-87).
()D21. FH1100 diode (#56-87). Save
one cutoff diode lead for use in the
following step.
()Ferrite bead. Use a1" cutoff diode
lead.
FERRITE
BEAD
illlit CUTOFF
DIODE LEAD
DETECTOR CIRCUIT BOARD CONTINUE^
( ) R27. 2200 fi (red-red-red).
()R25. 330 12 (orange-orange-brown).
( ) R23. 100 kft (brown-black-yellow).
Form the leads as shown. Then mount the
resistor vertically.
{)R24. 330 S2 (orange-orange-brown).
()R21. 27 kfi (red-violet-orange).
( ) R22. 47 kfi (yellow-violet-orange).
()R26. 2200 SI (red-red-red).
()Solder the leads to the foil and cut off
the excess lead lengths.

NOTE: Before you install disc capacitors,
use long-nose pliers to remove the excess
insulation from the capacitor leads.
REMOVE COATING -
EVEN WITH BOTTOM
OF CAPACITOR BODY
()C24. .001 pF disc.
()C23. .001 /iF disc.
()C22. .01 fiF (103) ceramic. Do not
use the disc capacitor here. Tip the
top of this capacitor toward the
nearby resistors.
(>C25. .001 pF disc.
()C26. .01 uF disc.
()C27. .01 nF (103) ceramic.
()Solder the leads to the foil and cut off
the excess lead lengths.
PICTORIAL 1-2
CONTI NUEQ
NOTE: In the following step, line up the
locating tab on the transistor with the
locating tab of the outline on the circuit
board and insert the leads into the correct
holes as shown. Solder the transistor leads
to the foil and cut off the excess lead
lengths. If there is ashorting spring on the
transistor leads, remove and discard the
spring.
SHORTING.
SPRING
1/8"
NOTE: Be sure to mount this transistor just
1/8" above the top of the circuit board.
()Q21.40673 transistor (#4 17-274 )
.

16
START
)S21. Pushbutton switch. Be sure to
push the switch firmly, all the way
down onto the circuit board. Then
solder its six lugs to the foil.
()C21A, C21B. Tuning capacitor.
Mount the capacitor to the circuit
board with three 6-32 x3/16"
screws and three #6 flat washers as
shown below. Be sure to place the
flat washers between the capacitor
and the circuit board.
m,FLAT
WEI
CUT GROUND
TERMINAL TO 5/8"
3V* %3
/a 1(INCHES) 2
I1/B .3/8 I5/8 7/8 I . I
ImM"^ 1
'i
1
1
1
i
1
1
i
CONTINUE
()Cut the ground lug to 5/8" from the
corner of the tuning capacitor
frame.
()Refer to Detail 1-3A and form the
ground lug as shown.
CIRCUIT BOARD CHECKOUT
Carefully inspect the circuit board for the
following conditions.
()Unsoldered connections. NOTE: Do
n« solder tuning capacitor lug 1
.
()"Cold" solder connections.
()Solder bridges between foil patterns.
( ) Protruding leads which could touch
together.
{)Transistor for the proper installation.
()Diodes for the correct position of the|
banded end.
()Be sure the case of transistor Q21 does
not touch tuning capacitor lug 1
.
NOTE: At this time, there are two small
unused holes in the circuit board.
Set the circuit board aside temporarily.

OSCILLATOR CIRCUIT BOARD
Position the oscillator circuit board as
shown. Then proceed with the following
steps.
()Cut one lead of a47 pF mica capacitor
to 1/4" and cut the other lead to 3/4".
Bend the longer lead straight out, and
the short lead toward the side as
shown.
>1/4'
()In the same manner, prepare another
47 pF mica capacitor. Bend the short
lead in the opposite direction to the
one in the previous step.
NOTE: In the following steps, push the
short capacitor lead into the circuit board
hole. Position each mica capacitor flat on
the circuit board as shown. Then, solder
each capacitor to the foil as you mount it
and cut off the excess lead length.
()C12.47 pF mica.
C1 1.47 pF mica. SPONGE OR CLOTH.
Page 17
CONTINUED
()R11. 470012 (yellow-violet-red).
()R13. 100 kJ2 (brown-black-yellow).
()R16. 27 kJ2 (red-violet-orange).
()Remove the excess coating from the
leads of a.001 pF disc capacitor.
Then wrap the leads of the capacitor
around the leads of a27 J2 (red-
violet-black) resistor as shown.
Solder the leads as shown and cut
off the excess resistor leads.
()R12-C15. Mount the prepared
resistor-capacitor assembly.
()R14. 1500 Q. (brown-green-red).
()R15. 10 kSl (brown-black-orange).
()Solder the leads to the foil and cut off
the excess lead lengths.

Page 18
NOTE: In the following steps, line up the
locating tab on the transistor with the
locating tab of the outline on the circuit
board and insert the leads into the correct
holes as shown. Solder the transistor leads
to the foil and cut off the excess lead
lengths. NOTE: The 1/8" transistor height
above the circuit board is critical.
LOCATI MG
TAB
( ) Q11. MRF502 transistor (#417-290)
NOTE: Check to be sure no part of
transistor Q11 is touching th
resistor-capacitor assembly.
CONTINUED
NOTE: Before you install the following disc
capacitor, use long-nose pliers to remove the
excess insulation from the capacitor leads.
()C13. 5pFdisc.
()C14. .01 nF (103) ceramic. Save
both cutoff capacitor leads for use
later.
()Solder the leads to the foil and cut off
the excess lead lengths.
NOTE: To prepare awire, as in the
following step, first cut it to the indicated
length and then remove 1/4" of insulation
from each end. Tightly twist each wire end
and apply asmall amount of solder to hold
the small strands together.
( ) Prepare a5" blue wire.
()5" blue wire at C. Solder the wire to
the foil and cut off the excess wire
length. The free end will be connected
later.