Astron makes both linear and switching power supplies, and some other products.
You should read this Astron Introductory Information article before any of the other articles here in the Astron section
It has some very useful information on the Astron linear and switching power supplies, with background, history, model-specific information, modification suggestions, photos, and more.

Reset circuits for Astron Linear Series Power Supplies

• An external reset circuit for the Astron Linear series     A reset circuit by Kevin K. Custer  W3KKC
• An internal reset circuit for the Astron Linear series     A reset circuit provided by The Astron Corporation
  If you are inside your Astron for some other reason it's worth adding this circuit as long as you have the cover off... Just remember to print the page and leave a copy inside the case so the next guy will know what the little circuit on the piece of perfboard is for.

Modifications for Astron Linear Series Power Supplies

• Float Modification for the RS/RM‑35A/S     Schematic of the Astron RS‑35A/M with float modification   (the yellow highlighted area)
  If you add a toggle switch to the front panel that shorts out the added resistor you can label it "Float" (when off / open) and "Normal" (when on / shorted).
  Make sure you print the mod sheet and tuck it inside the supply for the next guy...
• Adding Anderson PowerPole Connectors to an SS‑30 supply   By Robert Schulz KC6UDS
  This is a very nicely done modification that extends the usability of the SS‑25 or SS‑30 supply.
  Kyle Yoksh KØKN took Robert's idea and modified a Daiwa PS‑304 power supply in a similar fashion.

Battery Back-up Modification for Astron Linear Series Power Supplies
If you inspect the circuit diagram you will see that the BB option is simple - it consists of two diodes that allow either the power supply or the battery to feed the load. In the low current supplies they use half of a bridge rectifier, in the high current supplies they use two separate diodes in parallel for each current path.   The charging circuit is not well designed as it is just a single resistor from the battery to the output of the supply (look for R103 in the schematic for the RS‑12‑BB and RM‑35A‑BB)... and this simple charger circuit can boil your battery dry!   This circuit requires you to have the supply voltage set EXACTLY at the sum of the diode voltage drop plus the battery float voltage regardless of what the voltage your load wants to see (and the voltage drop across a diode varies slightly from low-load to full-load).   Overly simple charging circuits ALWAYS leave lots of room for improvement.   But the circuit that is shown does give you a starting point to design a better one.   Or if you have an external charger (like a Deltron "Battery Tender") you can simply remove R103 (or it's equivalent in larger supplies).   Or mount a toggle switch on the front panel of the supply near the diodes, wire it in series with R103 and label it as "Internal Charger Enable / Disable".   Or replace it with a multi-stage charger board added inside the cabinet.

• Schematic of the RS‑12A‑BB     Factory Battery Back-Up Schematic donated by John Lund
• Schematic of the RM‑35M‑BB / RM‑35A‑BB     Factory Battery Back-Up Schematic donated by Larry Horlick VYØHL
  Note that the schematic title block says that it is for both the RM-35M-BB (rack mount, w/meters), and the RM-35A-BB (rack mount w/o meters), but the schematic does not have any metering components.   If you need metering look at the next one and copy that section.
  The metered version of this supply is also known as a Motorola RRDN6933A, which comes with lighted meters (the first that anyone that I know has seen with that feature).
• Schematic of the RS/RM‑50M‑BB     Factory Battery Back-Up Schematic donated by Robert Burton KD4YDC

The Library - Schematic Diagrams of some popular Astron Linear Power Supplies

Please realize that you will find multiple different schematics listed below for the same supply as the designs changed over the years - due to parts availability, circuit improvements, etc.   For example, the early supplies use discrete stud-mounted diodes instead of half of a bridge rectifier (switching to a epoxy bridge module, despite the fact that only half is used, is one of the tricks that the designer at Astron used to lower the parts cost and manufacturing labor cost).   You may have to download more than one schematic to get the one that matches your supply, and you may not find your schematic at all (as we only have the ones that were donated to us).   If you have one that we don't, please consider sending us a scan or a xerox copy.

We have received emailed requests for schematics on the model 1212 and 1212-18 switching regulated converters and for the model SS10, SS18, SS25, SS25M supplies.

When (or if) you find the schematic that matches your unit I suggest you print it and stuff a copy inside a plastic page protector, and tape it to the underside of the lid of the power supply cabinet !   Several folks have mentioned in emails and on mailing lists that you can call Astron on the phone and you will hear them tell you that they don't have electronic copies of their drawings and they don't know how to email them.   Trust me, the person that answers the phone will be amazed when you tell them that the drawings from different years for the same model power supply show some different component ID's and values.   Unfortunately this is important because if one chooses to buy replacement parts (from Astron) they (according to Astron) need only to supply the model and component ID's....  Fortunately everything but the filter caps, transformer, and sheet metal are common Mouser or DigiKey parts.   And I bet you could find the capacitors if you tried hard enough.   Astron has to get them from somebody.

Notes:

• An "RS‑" prefix is a standard power supply. I suspect that RS stands for Regulated Supply.
• An "RM‑" prefix instead of "RS‑" prefix indicates a rack-mount power supply (i.e. packaged to mount in a 19 inch rack).   This packaging is only offered on the larger supplies. Usually there is little (if not zero) electronic difference between the RS‑ series and the similar RM‑ model.
• Change the first letter from R to V and you have one with front panel adjustments (V=variable).   Converting a RS or RM to a VS or VM usually involves adding two potentiometers to the front panel and making the wiring changes shown in the schematic.
• SS‑ series are switching power supplies - their schematics are further down the page.
• SL‑ series - you'd think that the leading "S" would imply a switching supply, but these are low profile supplies. Really, they should have been RL‑
• A trailing "M" indicates the metering option.
• A trailing "ML" indicates the lighted meters option.
• A trailing "S" is the speaker version.
• A trailing "BB" indicates the battery backup option.   See the comments above on the battery backup feature.

Astron builds supplies for several manufacturers - for example a Kenwood KPS-12 is based on the Astron RS‑12, the Motorola HPN1007A (photo) is an RS‑10 derivative, and the Motorola HPN9041 is an RS‑20 variant.   Astron also builds supplies for EF Johnson, GE, Icom, Midland, Uniden and Vertex.

Donations of additional schematics for the library below are always welcome !!
Send them to Mike WA6ILQ at: (callsign) -at- repeater-builder -dot- com - and thanks in advance!
(you will be credited unless you tell us to assign it to A. Nony Mous)

See the "Notes" section above for an explanation of the prefix and suffix letters

If you don't find the schematic for your Astron below then we were not given it.

• RM-60A, RM-60M   42 KB PDF, dated 08-16-1988 donated by Tom Allinson WB6DGN
  
• RM-60A, RM-60M   395 KB PDF, dated 08-16-1988 but dated on the lower left of the schematic 03/20/96   Donated by Mike Morris WA6ILQ
  
  The RM series has a 60 amp model, the RS series does not.   At the moment this is the only RM-specific model in the library.
  
  
• RS-3A and RS-4A   364 KB, dated 12-89   Donated by Oscar Ramsey NV3G
  (The draftsman obviously started with the RS-7 schematic... he forgot to adjust the voltage table... it shows a 7 amp load...)
  
  
• RS-7A   70 KB, dated 10-94   Donated by Mike Morris WA6ILQ
  
  
• RS-10A, RS-10S   105 KB, dated 9-81   Donated by Bill Netzlof KL7IGB
  
  
• RS-10A, RS-10S   368 KB, dated 9-88 (but rubber stamped Sept 22 2003 on the drawing)   Donated by George Franklin WØAV
  
  
• RS-12A   199 KB, dated 11-83   Donated by Richard Reese WA8DBW
• RS-12A, RS-12M   125 KB, dated 6-88   A. Nony Mous found this on a Russian web site and forwarded it.
• RS‑12A‑BB   119 KB, dated January 2000   donated by John Lund.   See the comments above on the battery backup feature.
  
  
• RS-20A   71 KB, dated 11-12-1978   Donated by Gary Eldridge KC8UD
• RS-20A, RS-20S   79 KB, dated 9-23-88   Donated by Kevin Custer W3KKC
• RS-20A, RS-20S   185 KB, dated 9-24-88   Donated by A. Nony Mous
  
  
• RS-35A   135 KB, dated 1-11-1978   Donated by Joe McIntyre W4DEX
• RS-35M   46 KB, dated 4-87   Donated by Kevin Custer W3KKC
• RS-35A, RS-35M   216 KB, dated 4-87 but different   Donated by Mike Morris WA6ILQ
• RS-35M   47 KB, dated 4-87, again different   Donated by Mike Morris WA6ILQ
  Thanks to Ed Lambert K1ZOK who pointed out that there was an important error in this schematic file (the repeater-builder staff edited the image file and corrected it). There was an extra "line" drawn between the collector of the TIP29 and the bases of the pass transistors. This, effectively, shorted out the regulator driver Q2.   If you downloaded this schematic in the past you may want to get a fresh copy and replace your incorrect copy.
• RS-35A, RS-35M   900 KB PDF, dated 5-91   Donated by Mike Morris WA6ILQ
• RS-35A, RS-35M   87 KB PDF, dated 5-95   Donated by Mike Morris WA6ILQ
• RS-35M   498 KB JPG, dated Jan-2000   Donated by A. Nony Mous
• RM‑35A‑BB   76 KB PDF, dated January 1993 donated by Larry Horlick VYØHL
  This is a factory Battery Back-Up supply that is also known as a Motorola RRDN6933A.   See the comments in the battery backup section above concerning this particular supply.
  
  
• RS-50M   182 KB, dated dated Jan-2000   Donated by Kevin Custer W3KKC
• RS-50A, RS-50M, RM-50A, RM-50M   44 KB PDF, dated 03-21-96 donated by Tom Allinson WB6DGN
• RS-50A-BB, RS-50M-BB   127 KB, dated 7-95   Donated by Robert Burton KD4YDC   See the comments above on the battery backup feature.
  
  
• RS-70A, RS-70M   87 KB, dated 4-87   Donated by Henry Clark KC4KZT
• RS-70A, RS-70M   73 KB, unreadable date (probably 8-88)   Donated by Mike Morris WA6ILQ
• RS-70A, RS-70M   227 KB, dated 6-97   Donated by Avent Lane
• RS-70A, RS-70M   69 KB PDF, dated January 2007 donated by Tom Allinson WB6DGN
  
  
• VS-20M   1.02 MB, dated 11-12-78   Donated by A. Nony Mous
• VS-20M   74 KB PDF dated January 2000 donated by Larry Horlick VYØHL
  This supply is also known as a Motorola RRDN6082A. The Moto invoice says "VS-20ML" which Larry assumes to mean metered and lighted.
  
  
• VS-35M   322 KB, dated 1-87   Donated by Steve Duncan, WA4ITA
  
  
• VS-50M   25 KB PDF, dated 8-82   Donated by Bob Shields, KA9TYL
  
  
• VS-70M   132 KB, dated 6-30-95   Donated by Brian Palmersheim KBØETC

Schematic Diagrams of some other popular Astron Switching Power Supplies

• SL-15 low profile supply   135 KB   Dated 4-15-1990   Donated by Ed Lambert K1ZOK
• SS-12 switching supply   55 KB,   Dated 8-22-1996   Donated by Eric Lemmon WB6FLY
  No parts values other than what Eric noted.
• SS-30 switching supply   70 KB,   Dated 9-25-2000   Donated by Eric Lemmon WB6FLY
  No parts values other than what Eric noted.
• A mod for the Astron SS-25 and SS-30 power supplies (and maybe other SS-series) from NU4G: These two power supplies use a simple normally open "click" thermostat to switch a very noisy (acoustic noise, not RF noise) fan on and off. The fan noise can be annoying at times, so I've modified my supplies to make it less so. Open the supply after first disconnecting AC power and allowing for DC voltage to bleed down. Looking inside you will see two sets of heatsinks near the rear of the unit. Each heatsink has a thermostat, the left side heatsink has a normally closed 50 degree C thermostat for the AC input - don't bother it. The right side heatsink has the fan thermostat mounted to it. The fan thermostat switches DC from the output to power the fan. If you bridge the thermostat with a two watt resistor of 75 to 100 ohms the fan will be on continuously, but very slowly. This slow speed is enough to keep the supply cool with very little noise. Before installing this mod simply running my 756PII on receive was enough to turn on the fan every 5 minutes or so. With the mod I've only had the fan go to full speed (i.e. the thermostat closed) while operating RTTY for an extended time on a very warm day.
  This mod may or may not apply to other models of Astron switching power supplies.
• 2412 Switching Regulated Converter   140 KB,     Donated by Ed Lambert K1ZOK
  This unit allows you to use a +12v device (like a two-way radio) on a +24 volt battery system (like in many Kenworth, Peterbilt and other large trucks, for example, fire trucks). The negative side is common. If you need a ground inverting unit there are transformer-based units from other companies that allow a negative source voltage (i.e. from -24v to +12v).

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