[SMCARA] Forgotten Astron information page.

[Clarke, Tom AIR4.0P NATOPS]

Right on Ren!  I can recommend the following for any Astron PS:

1.	Add 470pf compensation capacitor to 723 regulator chip.  Pin 4 to 13. Lowers noise on DC line and reduces RF upsetting the regulator.
2.	Check solder joints on Collector tabs on 2N3771 pass transistors.  May be loose.
3.	If diode pack is bad or consists of two small blocks, replace with one 1kv 50 amp block.
4.	Replace pass transistors with 2N5686 or 2N3771 (if using 2N3055 or ECG181). Newer ones seem to have the 3771s already installed.
5.	Add split ring or star washers to pass transistor mounting hardware. This ensures a good low loss connection in the high current connections.	
6.	Add 0.1 mf to ground from + output of bridge or full wave diodes.
7.	Add 0.01 mf across AC line and to ground. Parallel caps with MOVs. Make sure you use X2 250 volt caps rated for across AC line use.  Use Y caps for AC line to ground use.
8.	Change power cord to IEC cord fitting from old PC power supply.  Nibble out existing AC line cord hole to fit.  Filtered plug is even better.
9.	Add a remote 1K carbon pot to front panel for voltage adjustment.  Use shielded wire to PC board 	and put ferrite beads on wires at PC card end.  
10.	Add an LED to panel since the neon in switch usually dies. Yep it does!
11.	Add 2 small 24 volt fans to cool heat sink.  Run slower and quieter on 12v.  
12.	Cut small vent holes in case and install 24 volt fan to cool inside of case.  Use metal screen on holes for shielding.
13.	Check all soldered connections and fasteners for security.  Some power supplies have poor connection to green safety ground on AC line cord in PS. Mine was riveted. Drill out and use 6-32 hardware with star washer. Clean paint off the case to 	ensure a good contact.
14.	I also added a 01 cap across the output terminals and a toroid with 8-10 turns of #16 wire, inside the case, to keep the RF out.

Any or all are good.

73 Tom/W4OKW


-----Original Message-----
From: SMCARA [mailto:smcara-bounces at mailman.qth.net] On Behalf Of Rene Ramirez
Sent: Tuesday, December 08, 2015 2:19 PM
To: SMCARA Reflector
Subject: [Non-DoD Source] [SMCARA] Forgotten Astron information page.

I forgot all about this website.  Wealth of knowledge and mods and schematics for your Astron linear power supply.

www.repeater-builder.com/astron/astron-index(dot)html
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