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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.
Copyright Antique Wireless Association 2023 –
www.antiquewireless.org
1
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Summary of Contents for AWA HP-23
- Page 1 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.
- Page 2 AWA PCB UPGRADE PARTS LIST W/Alternate Parts V1.4 REPRESENTATIVE QTY: DigiKey# Mfg# Value: Used: Notes: 493-4352-ND LGN2H151MELC25 150UF 500V C1 C2 C3 C4 DigiKey ↑ 493-6783-ND LGX2H151MELC25 ↑ ↑ ↑ DigK Alt. ↑ 338-1975-ND 380LX151M500A012 ↑ ↑ ↑ DigK Alt.
- Page 3 #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.
- Page 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.
- Page 5 Copyright Antique Wireless Association 2023 – www.antiquewireless.org 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...
- Page 6 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.
- Page 7 Copyright Antique Wireless Association 2023 – www.antiquewireless.org 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.
- Page 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.
- Page 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.
- Page 10 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.
- Page 11 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.
- Page 12 Copyright Antique Wireless Association 2023 – www.antiquewireless.org AWA HP23 PCB Assembly and Installation Figures Pg 1 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.
- Page 13 AWA HP23 PCB Assembly and Installation Figures Pg 2 HP-23 & HP-23A Models ONLY: Leave Pot, 2 10KΩ Resistors, Term Strip L, and Green Wire from Pot to Pin 11 of 11 pin Socket To E11, ADJ BIAS REMOVED Choke Leads X X X Fig.
- Page 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 SPLICES RED 1KV WIRE BLU PIN 4 HV To 11 Pin ORG PIN 3 B+...
- Page 15 AWA HP23 PCB Assembly and Installation Figures Pg 4 Fig. 13 PCB Schematic Copyright Antique Wireless Association 2023 – www.antiquewireless.org...