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Potential Astron power supply failure solved!
1 December 2019 | by 
One of my blog readers informed me regarding the Astron linear power supply that the outer case on the pass transistors at the rear of the supply are live with about 24 volts. These pass transistors are isolated from the case and the heat sink so the potential is there to inadvertently via a PL259 connector, USB cable or any other conducting item at the rear of your setup to short the pass transistor and destroy them. This morning I once again was searching the internet to see if anyone had devised a solution for this very issue. I came across a web page . This individual has the RS-35A power supply and came up with a great solution using a 3D printer. Now I am not at all up on the whole 3D printer thing but click on the link above (web page) and have a look at the pictures they posted. The covers look great and are very professional looking. It would look to me the plans are available to those who have access to a 3D printer to produce the guards them self. I would really like a set of these for my RS-25 but just short on the 3D printer part of things.
To my fellow bloggers have a look at the above link and do post any 3D printer info you may have as well.
As a side note below are some links to great information regarding Astron power supplies.
http://www.wb1gof.org/files/AstronPDF.pdf
http://www.repeater-builder.com/astron/pdf/astron-troubleshooting.pdf
http://www.repeater-builder.com/astron/astron-repair/astron-repair.html
https://www.ecse.rpi.edu/courses/CStudio/ham_radio_docs/astron-repair-index.htm
12 Responses to “Potential Astron power supply failure solved!”
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I found this a while ago and printed them out. Works great, especially if you have them in black, blends right in. Since I always have cables and wires hanging down the back of the desk I thought these were a must have.
I’ve been using Thermalloy transistor covers for close to 40 years. MUCH easier than messing around with the 3D printing business.
One source here:
https://www.westfloridacomponents.com/G619APH07/TO3+Transistor+Insulating+Cover+Aavid+Thermalloy+8903VBG.html
Mike,
Try public libraries for 3D printers for public use! Those that have them just charge a bit for the materials.
There are also plenty of 3D printing services online, and probably in your area as well.
Good evening Ron and thanks for taking the time to leave a comment, first off I checked out your page on QRZ.COM and nice 3 monitor setup! I just ran across this site that has the protectors and it’s good to read that you downloaded and printed via a 3D printer and that they are serving you well.
73 and have a good upcoming week.
Mike
VE9KK
Hello Brian very nice to hear from you, well up this way in New Brunswick, 3D printers are nowhere to be found in libraries. But another blog reader left a comment here informing me that I could go online and look for a 3D printing service.
Thanks, Brian for stopping by and commenting.
73,
Mike
VE9KK
Good evening Bob from New Brunswick, I never even thought about going online and sourcing it this way. My only issue would be that the online 3D plans are for the Astron RS-35 and I have the Astron RS-25 and the specs could be different……..but having said that it sure does give me a start to move in the right direction.
Bob have a great upcoming week and thanks for stopping by the blog and giving it a read.
73,
Mike
VE9KK
You can buy transistor covers for the TO-3 devices on these power supplies, for instance, this: https://www.digikey.com/product-detail/en/keystone-electronics/4634/36-4634-ND/316224
Not expensive.
Jeff n1kdo
This is a lot easier than printing.
https://www.ebay.com/itm/Insulation-PVC-Cap-for-TO3-Packages-Transistor-Cap-TO-3-2-pieces-/132682522616
Good afternoon Jeff thanks for taking the time to comment and leaving a link, I was just wondering if these caps since they have no ventilation would the transistors overheat?
Thanks
Mike
VE9KK
Good afternoon Lowell, very nice to hear from today and yes they are cheaper but my question is the same as it was for Jeff……with covering the transistors in plastic with no ventilation would this cause them to heat up?
Have a good week Lowell
73,
Mike
VE9KK
Good evening Dave, very sorry missed your comment entirely………it happens with old age if you have been using them on Astron supplies and had no issues then the subject is closed regarding hunting out a 3D printed solution. Thanks for the info and I am going to order 2 of them so look after my Astron supply.
73
Have a great rest of the week
Mike
VE9KK