AWA HP-23 Quick start guide
1
AWA Heathkit HP-23 Power Supply PCB Upgrade Instructions V1.4
Thank you for purchasing the AWA Heathkit HP-23 Power Supply Upgrade Board.
This board will allow easy upgrading of all diodes, capacitors, and resistors for extended
life of your HP-23 power supply.
Note: This printed circuit board upgrade is intended only for persons experienced in
working with high voltage circuitry. The completed upgrade and associated components
produce potentially dangerous voltages. Always install the Heathkit HP-23 perforated
metal cover when operating the HP-23.
There were at least five different versions of the HP-23 supply starting with the
HP-23 then the A, B, and C models and ending with the PS-23. They all have the same
4 basic outputs: High Voltage, HV, at 700VDC @250ma, B+ at 300VDC @150ma or B+
at 250VDC @100ma, Bias at -100VDC @20ma, filament at 12.6VAC @5.5A. Earlier
versions had a switch for Hi or Lo B+, adjustable and fixed Bias voltage, and could
supply 6.3VAC and 12.6VAC for filaments, and were 120VAC input only. Later versions
eliminated the switch for Hi or Lo B+ and were hard wired, the Bias voltage was fixed,
and the filament voltage was only 12.6VAC. The AC input could be wired for 120 or
240VAC.
The AWA PCB should be usable in all these versions.
The AWA Upgrade PCB uses diodes in the HV section (D1,D2,D3,D4) upgraded to
1000PIV and 1A (1N4007) or optionally, 1000PIV and 3A(1N5308). Diodes D5,D6,D7
are 1N4007s. The HV and B+ caps C1-C4 were upgraded to 150uF at 500VDC. B+
cap C5, is upgraded to 47uF at 450VDC. Bias caps, C6 and C7 are upgraded to 47uF
at 200VDC. The PCB is designed to use modern, snap-in caps with 10mm lead
spacing. Leaded (or taller snap-in caps) caps can be used but must be less than
approx. 1.7” in height to prevent hitting the filter choke with the PCB mounting
suggested. The bleeder resistors specified are TE Connectivity ROX series metal oxide
with a flameproof rating. These have a 5 watt rating and are a little smaller than a 2
watt carbon comp resistor. R8, is a 0.33Ω, 3W additional resistor recommended in a
HP-23 upgrade article by Mike Bryce, WB8VGE in October, 2003 QST. This resistor in
the B+ output is supposed to limit current for a short period of time if the B+ is shorted.
This can be jumpered out, if desired. Another option feature to the original circuit is to
add a HV fuse (F2). This is a 0.25” x 1.25” (3AG) size fast blow fuse rated 500ma at
1000V. This is a SIBA fuse part# 7017240 widely available as it is used as a multimeter
protection fuse. This can be jumpered out, if desired, also.
The PCB board is mounted vertically using the old HV filter cap mounting holes located
near the outside edges of the chassis closest to the transformer. The board is mounted
using 2 Keystone #614 Angle Brackets and #6 hardware. The 2 screws in the vertical
(threaded) leg of the angle bracket can be removed to allow easy board removal for
repairs, etc. The board is 4.50” wide and 3.90” tall. Angle bracket mounting holes are
4.10” apart to match the old filter cap mounting hole centers.
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2
AWA PCB UPGRADE REPRESENTATIVE PARTS LIST W/Alternate Parts V1.4
QTY:
DigiKey#
Mfg#
Value:
Used:
Notes:
4
493-4352-ND
LGN2H151MELC25
150UF 500V
C1 C2 C3 C4
DigiKey
↑
493-6783-ND
LGX2H151MELC25
↑↑
↑
DigK Alt.
↑
338-1975-ND
380LX151M500A012
↑↑
↑
DigK Alt.
↑
598-
80LX151M500A012
380LX151M500A012
↑↑
↑
Mouser
Alt.
↑
594-
MAL215919151E3
MAL215919151E3
↑↑
↑
Mouser
Alt.
1
A142834CT-ND
ROX5SSJ27K
27KΩ5W
R7
DigiKey
↑
279-ROX5SSJ27K
ROX5SSJ27K
↑↑
↑
Mouser
Alt.
1
A142800CT-ND
ROX5SSJ1K0
1KΩ5W
R6
DigiKey
↑
279-ROX5SSJ1K0
ROX5SSJ1K0
↑↑
↑
Mouser
Alt.
5
A142848CT-ND
ROX5SJ100K
100KΩ5W
R1 R2 R3 R4 R5
DigiKey
↑
279-ROX5SJ100K
ROX5SJ100K
↑↑
↑
Mouser
Alt.
1
A138093CT-ND
ROX3SJR33
0.33Ω 3W
R8
DigiKey
↑
279-ROX3SJR33
ROX3SJR33
↑↑
↑
Mouser
Alt.
1
1189-1784-ND
450MXC47MEFCSN20X25
47UF 450V
C5
DigiKey
↑
338-3659-ND
380LX470M450H202
↑↑
↑
DigK Alt.
↑
710-861111483002
861111483002
↑↑
↑
Mouser
Alt.
2
493-16452-ND
LAK2D470MELZ20
47UF 200V
C6 C7
DigiKey
↑
338-3659-ND
380LX470M450H202
↑
↑Same as C5
DigK Alt.
↑
710-861111483002
861111483002
↑
↑Same as C5
Mouser
Alt.
↑
710-861111483002
861111483002
↑
↑Same as C5
Mouser
Alt.
4
1N5408GOS-ND
1N5408G
1N5408 3A
1KV
D1 D2 D3 D4
DigiKey
↑
1801-1N5408GCT-
ND - Cut Tape (CT)
1N5408G
↑
↑
DigK Alt.
↑
621-1N5408G-T
1N5408G-T
↑
↑
Mouser
Alt.
3
2368-1N4007-ND
1N4007
1N4007 1A
1KV
D5 D6 D7
DigiKey
↑
1N4007-TPMSCT-
ND - Cut Tape (CT)
1N4007-TP
↑
↑
DigK Alt.
↑
637-1N4007
1N4007
↑
↑
Mouser
Alt.
2
36-614-ND
Keystone 614 Bracket
N/A
MB1 MB2
DigiKey
↑
534-614
↑
↑
↑↑
Mous Alt
1
576-03540101ZXGY
03540101ZXGY
N/A
FUSE HOLDER
Mouser
3
1
283-5081-ND
BK1/TDC11-500-R
0.5A 1000V
F1
DigiKey
↑
Alternate Fuse
SIBA 7017240
↑↑
↑
SIBA
2
Generic Part
#6-32 x ¼” Panhead Screw
PCB Mounting
2
Generic Part
#6-32x3/8” Panhead Screw
PCB Mounting
2
Generic Part
#6-32 Nut
PCB Mounting
2
Generic Part
#6 Flat Washer
PCB Mounting
2
Generic Part
#6 Lock Washer
PCB Mounting
Note: Only the Digi-Key Parts have been tested in the AWA prototype boards. The alternate parts
should be acceptable substitutes but the user should check their usability. Because of the current
supply issues, substitutes may be needed. For instance, leaded capacitors could be adapted to this
board. The capacitors specified are used because they all have 10mm lead spacing to match the board.
The fuse holder can also be found at online auctions sites and has a 1-3/8” lead spacing to match the
board holes and is for a type 3AG fuse.
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4
PCB Assembly:
First check that all the PCB parts are available for assembly. Rosin core
60/40 tin/lead solder will be required along with a medium tip soldering iron.
Refer to the Assembly and Installation Figures at the end of this manual for the
following steps.
[ ] Check the box next to each step after each step is done.
[ ] Position the PCB with the mounting hole, MB1, at the lower left
corner.
[ ] Assemble diodes D5, D6 and D7 (1N4007) flat against the board
with the white bands on the diodes over the bands on the board.
Bend the leads to hold in place. Solder the leads, six places. See
Fig. 1
[ ] Bend the lead of diode D1 (1N4007 or 1N5308) next to the white
band down along side of the diode body. Do the same for diodes D2,
D3, and D4. See Fig. 2
When installing diodes in the following steps, ensure they are
vertical and straight.
[ ] Install these four diodes with bent lead towards the top edge of the
board. Bend the beads to hold in place. Solder the leads, eight
places.
[ ] Install capacitor C1, 150uf 500V by snapping it into board making
sure the white capacitor strip (-) is over the white semi-circle on the
board. All the following capacitors have the white strip facing the
right side of the board. Solder the 2 capacitor pins. See Fig. 3
[ ] Like wise, install capacitors C2, C3, and C4, 150uf 500V by snapping
into the board. Solder the 6 capacitor pins.
[ ] Like wise, install capacitor C5, 47uf 450V by snapping into board.
Solder the 2 capacitor pins.
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[ ] Likewise, install capacitors C6 and C7, 47uf 200V by snapping into
board. Solder the 4 capacitor pins.
[ ] Bend the lead of resistor R1(100KΩ 5W) down along side of the
resistor body. Do the same for resistors R2, R3, and R4
(all 100KΩ 5W). See Fig. 4
When installing resistors in the following steps, ensure they are
vertical and straight.
[ ] Install resistors R1 and R2 with the bent lead towards the left.
Bend leads over on the foil side and solder 4 places. See Fig. 4
[ ] Install resistors R3 and R4 with the bent lead towards the right.
Bend leads over on the foil side and solder 4 places. See Fig. 4
[ ] Bend the lead of resistor R5 (100KΩ 5W) down along side of the
resistor body. Do the same for resistors R6 (1KΩ 5W),
R7 (27KΩ 5W), and R8 (0.33Ω 3W). See Fig. 5
[ ] Install resistor R5 (100KΩ 5W), with the bent lead towards the right.
[ ] Install resistor R6 (1KΩ 5W), with the bent lead towards the bottom.
[ ] Install resistor R7 (27KΩ 5W), with the bent lead towards the top.
[ ] Install resistor R8 (0.33Ω 3W), with the bent lead towards the left.
This resistor is optional and may be jumped out, if desired.
[ ] Install a HV insulated jumper wire at the F1 Fuse holder location
if the HV Fuse will NOT be used. As an alternate, a bare jumper wire
can be installed on the back side of the board. If the HV Fuse option
is to be used, install the Fuse Holder at the F1 location. See Fig. 6
Install the 500Ma, 1000V fuse in the holder, if used.
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6
[ ] Install the “L” mounting brackets at locations MB1 and MB2.
The leg with the tapped hole goes on the back side of the board.
Use a #6-32 pan head screw ¼” long with a flat washer on the front
side of the board. Tighten only loosely in this step. See Fig. 7
[ ] This completes the component assembly of the printed circuit board.
HP23 Chassis Preparation
[ ] A manual with schematic diagram for your model HP-23 will be useful
in the following steps. In the following steps, save any screws,
lockwashers, and nuts from the 4 large capacitor mounts that will be
removed for future use in mounting the PCB.
[ ] Remove the top cover and remove any dust or dirt that may have
accumulated. Remove the bottom cover.
{ } When cutting wires that go to the transformer, choke, and 11 pin
output socket, leave the length as long as possible. Most wires will
be spliced to reach connections on the PCB. On early versions of the
HP-23, the transformer wire colors may be faded and hard to
determine. After disconnection, the transformer and choke windings
should be checked with an ohmmeter for correct value. The approx.
values are:
HV (Red to Red/Yel): 19Ω
B+ Hi Tap (BRN to BLU): 8.4Ω
B+ Lo Tap (BRN/YEL to BLU): 6.5Ω
Filter Choke (RED to BLK): 95Ω
[ ] If any of the transformer wires are faded, they can be marked with a
short length of colored shrink tubing, a paint pen, or a piece of
colored tape.
[ ] In the following steps, if you have a HP-23 with the Bias
Potentiometer, do not remove resistors R8 & R10 (10KΩ 1W) which
are connected to the Potentiometer outer terminals. Also, do not
remove the 4 position terminal strip. See Fig. 8.
7
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[ ] Referring to Fig. 8, remove all the diodes by clipping their leads close
to the body. The parts to be removed are marked by Xs.
[ ] Remove the resistors by clipping their leads close to the body.
The parts to be removed are marked by Xs.
[ ] Remove the 3 capacitors on the left by clipping their leads close to
the body. The parts to be removed are marked by Xs.
[ ] Remove the 4 large, black capacitors and their mounting plates.
Save the hardware. The parts to be removed are marked by Xs.
[ ] The AC Input wiring should not have to be disturbed.
[ ] Desolder the remaining clipped leads from the terminal strips.
Remove 1 of the solder lugs at location “M” and remove any wires
on the remaining solder lug.
[ ] In the following steps, the Transformer, Filter Choke and 11 Pin
Socket wires will be extended to reach connection points on the PCB.
They should be extended to provide enough length so the PCB can
be removed and worked on. Use 22AWG wire or larger.
The HV wire should be rated for 1000V.
[ ] Strip and tin the red and black Filter Choke leads about ¼”.Connect
the BLK lead to lug #1 of “J” terminal strip. Connect a 6” length of
BLK wire to this same lug and solder. Connect the RED lead to lug
#2 of “J” terminal strip. Connect a 6” length of RED wire to this same
lug and solder. See Fig. 8
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8
The Transformer leads will be extended in the next step.
[ ] Cut and strip 1 BLU 22AWG wire, 2 RD 22AWG wires,
and 2 BRN 22AWG wires 6” long. Add yellow markings to 1 of the
RED and 1 of the BRN wires.
[ ] Splice the BLU wire to the BLU Transformer wire and insulate
the splice with 3:1 (1000V Min Rating) shrink tubing.
[ ] Splice the RED wire to the RED Transformer wire and insulate
the splice with 3:1 shrink tubing.
[ ] Splice the BRN wire to the BRN Transformer wire and insulate
the splice with 3:1 shrink tubing.
[ ] Splice the RED/YEL wire to the RED/YEL Transformer wire and
insulate the splice with 3:1 shrink tubing.
[ ] Splice the BRN/YEL wire to the BRN/YEL Transformer wire and
insulate the splice with 3:1 shrink tubing.
[ ] Dress these 5 wires together and secure with 2 wire ties.
Pass these 5 wires through the old, lower left capacitor hole.
These wires will be connected in a later step. See Fig. 11
[ ] There are 3 ways the Hi Lo B+ voltage can be set.
[ ] Method #1: Install an insulated jumper wire between
point E12 and point E14 for 250VDC B+ OR
point E12 and point E13 for 300VDC B+.
Method #2: Install a white wire with a male bullet terminal on
one end. Connect the other end to point E12, “Select”.
Install a BRN/YEL wire with a female bullet terminal on one end.
Connect the other end to E14, “250V”. Install a BRN wire with a
female bullet terminal on one end. Connect the other end to E13,
“300V” See Fig. 9 and Fig. 12.
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9
Method #3: If you have a HP-23A or B model with the voltage select
switch, the wires from E12, Select, E13, 300V, and E14, 250V can be
wired to that switch. See Wiring Diagram, Fig. 12.
[ ] The insulated PCB Output wires will be installed on the PCB in the
next steps.
Cut a 12” RED HV wire and strip one end and tin (HV).
Connect this wire to PCB point E8 (+700V) See Fig. 12.
Cut a 12” ORG 22AWG wire and strip and tin one end (B+).
Connect this wire to PCB point E9 (B+) .
Cut a 12” YEL 22AWG wire and strip one end and tin (Fixed Bias).
Connect this wire to PCB point E10 (Fixed Bias).
Cut a 12” GRN 22AWG wire and strip one end and tin (GND).
Connect this wire to PCB point E15 (GND).
(GRY wire is used on HP23 and HP23A models only)
Cut a 12” GRY 22AWG wire and strip one end and tin (ADJ Bias).
Connect this wire to PCB point E11 (ADJ BIAS)
[ ] Starting at the top of the board, bundle these wires,
(E6 E9 E10 E11 E15) with 2 wire ties. These wires will
be connected after the PCB is installed.
[ ] Feed the 5 bundled transformer wires through the old capacitor
mounting hole in the lower left, Fig. 11.
[ ] Keeping in mind having some excess wire length for PCB removal,
cut the transformer wires so they will reach E1 E2 E3 E4 and E5.
Strip and tin these wires.
Connect the RED to PCB point E1.
Connect the RED/YEL to PCB point E2.
Connect the BRN to PCB point E3.
Connect the BRN/YEL to PCB point E4.
Connect the BLU to PCB point E5. Solder 5 connections.
[ ] Connect the RED Filter Choke wire to E6 and the BLK to E7.
10
Copyright Antique Wireless Association 2023 –www.antiquewireless.org
[ ] Install the PCB as shown in Fig. 7 using the #6-32 hardware shown.
Use the 2 outer holes of the old, large capacitor mounting location
closest to the transformer as shown in Fig. 7 Tighten the 2 PCB
screws in the vertical leg of the Keystone brackets.
[ ] In the following steps, place a wood block under the Filter Choke
when working with the chassis upside down to prevent bending the
PCB brackets.
[ ] Install the bundled PCB output wires through the old capacitor
mounting hole in the upper left, Fig. 11. Connect and splice these
wires as follows covering the splice with 3:! shrink tubing:
[ ] Red HV wire from E8 (700V) to BLU wire from 11 Pin Socket
Pin #4, (HV).
[ ] ORG wire from E9 (B+) to ORG wire from 11 Pin Socket
Pin #3, (B+).
[ ] YEL wire from E10 (F BIAS) to YEL wire from 11 Pin Socket
Pin #1, (F BIAS).
[ ] HP23 and HP23A models only: GRY wire from E11 (A BIAS) to
Resistor R8 (10KΩ), see Fig. 8.
[ ] GRN wire from E15 (GND) to GND Lug at location M, Fig. 8.
Do not solder at this time.
[ ] Cut a 10” BRN 22AWG wire and strip both ends and tin.
Connect one end to GND Lug at location M, Fig. 8 and solder 2 wires.
Connect, splice, and insulate the other end to BRN wire from 11 Pin
Socket Pin #7, (GND).
[ ] This completes the wiring of the HP-23.
11
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[ ] The following resistance checks can be made at the 11 pin Output
Socket before applying power.
Positive meter lead to pin #4 (HV) and negative meter lead to pin #7
(GND) = 99KΩ
Positive meter lead to pin #3 (B+ 300V) and negative meter lead to
pin #7 (GND) = 99KΩ
Positive meter lead to pin #7 (GND) and negative meter lead to pin
#1 (F BIAS) 27KΩ
[ ] Remember, HIGH VOLTAGE is involved in the next steps!
A variable transformer (e.g. Variac) is valuable for first time power
up, if available. Be aware that many popular digital multimeters
cannot measure voltages higher that 600VDC without damage. The
meter should have a 1000VDC range. Below are the typical voltages
measured with our test HP-23. A good test method is to start with
12VAC input.
Measure the HV, B+, and Bias voltages. They should be roughly 10%
of the full output at 120VAC input if things are working correctly. You
may want to bring up the voltage slowly at first power-up to check for
abnormalities. You may also want to stop raising voltage at 3 or 4
intervals on power-up to allow capacitor forming. Voltages at the 11
Pin Output Socket with 120VAC input: (Measured to GND, pin 7)
HV Pin 4, +846VDC No Load, (NL)
B+ Pin 3, 369VDC NL, 300V selected
B+ Pin 3, 275VDC NL, 250V selected
F Bias Pin 1, -135VDC NL
Nominal AC Input Amps NL, 0.19A
A PCB Schematic is shown in Fig. 13
Thank you for supporting the Antique Wireless Association.
Bonus HP-23 restoration tip:
Krylon has a spray paint that is a very close match to the dark Heathkit
green available at Lowes. This is Krylon Fusion All-in One Paint + Primer
5X in Matte Spanish Moss. This works well on the chassis and cover.
Many HP23s have light rusting. A couple of light coats of Krylon Satin
Black will make the transformer and Filter choke look like new.
12
Copyright Antique Wireless Association 2023 –www.antiquewireless.org
AWA HP23 PCB Assembly and Installation Figures Pg 1
+
WHITE
STRIP
Fig. 1 Diodes D5, D6, D7 Fig. 2 Diodes Fig. 3 Capacitor Assembly
D1, D2, D3, D4
Fig. 4 Resistor Assembly Fig. 5 Resistor Assembly Fig. 6 Fuse Holder
R1, R2, R3, R4 R5, R6, R7, R8
HP-23
Chassis
#6-32x1/4"
Pan Head Screw
PCB
Threaded
Hole
Keystone
#614 Bracket
#6-32x3/8"
Pan Head Screw
#6 Lockwasher
#6-32 Nut
#6 Flat Washer
PCB Bracket Assembly
Detail
PCB Mounting
Holes
PCB Mounting
Detail
Fig. 7 PCB Mounting Detail
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13
AWA HP23 PCB Assembly and Installation Figures Pg 2
X =REMOVED
X
X
X
X
X
X
XX
X
X
X
XXX
XX
X
X
To E11, ADJ BIAS
GRY
R8
HP-23 & HP-23A Models ONLY:
Leave Pot, 2 10KΩResistors, Term Strip L,
and Green Wire from Pot to Pin 11 of 11 pin Socket
GRN
Choke Leads
BLK
RED
BLK RED
12
X
Fig. 8 Chassis, Old Parts Removal
14
Fig. 9 B+ Select, 250 or 300VDC Fig. 10 PCB Installed
AWA HP23 PCB Assembly and Installation Figures Pg 3
Fig. 11 Completed Wiring, Chassis Bottom
Hi –Lo B+
Select
BRN
WHT
BN/YL
250V300V
RED
RED/YEL
BRN
BRN/YEL
SPLICES
To HP-23 Power
Transformer
RED
BLK
TO
HEATHKIT
CHOKE
RED 1KV WIRE
ORGYEL
GRN
BLU PIN 4 HV
ORG PIN 3 B+
YEL PIN 1 Fixed Bias
To Chassis GND Lug under
Choke mounting screw
To 11 Pin
Output
Socket
GRY To ADJ Bias Pot Resistor R8 See Fig 8
(Models HP23 and HP23A ONLY)
SPLICES
BRN PIN 7 GND
BRN
MB1
MB2
FUSE +700 B+ F BI A BI GND
E8 E9 E10 E11 E15
RED
RED/YEL
BRN
BRN/YEL
BLU BLU
PCB
Fig. 12 Wiring to PCB
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