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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

I picked up the new power supply last week on Friday from the post office just in time for the CQ WW CW DX contest. The power supply I ended up choosing was the Astron 30 amp switching power supply. Yes I wandered away from the linear power supplies and into the dark side of the switching power supplies. The supply had very good reviews and now that I am on a fixed budget the linear supplies were just a bit to high for the budget. I have been using this supply for over a week now and am very pleased with it. There is no"hash" from this supply that I have read about online with other switching supplies. I have used it in the CW contest and also this week on FT8 and it has not heated up at all. After repairing the Astron RS20 I decided to keep it as a back up supply just in case the new supply in the future lets me down.....BUT when I do use it I will keep its duty cycle in line to what it has been designed to handle and not what I was putting it through.

Repaired and working

The repairs to the Astron RS-20M are complete and the power supply I am happy to say is back up and running. In the process of sourcing out the parts that I needed a reader of my blog gave me a glowing recommendation of Digi-Key Electronics. I am very glad that he gave me the heads up regarding this company. When I went to the site you have the option of chatting live with an agent if you have any questions. I took advantage of this several times as I wanted to make sure I was choosing the correct items. The order was placed with them and immediately I received a

Negative to case ground

Confirmation email regarding the payment going through. Within an hour another email was sent informing me my items had been shipped along with a tracking number. My dealings with Digi-Key was outstanding, I had recently dealt with an Amateur radio store up  this way (when ordering my new Astron power supply). The only email I was sent informed me my order had been processed and that was it. I wondered if just the payment went through, if the order had been picked and or if the order had been shipped? I ended up calling them to see if it had been shipped I asked when I may expect it to arrive, so I would make sure I was home as it needed a signature. The person on the phone sounded very put out as it required them to do some digging. They did return to the phone informing me it had been shipped and should be here by Friday. When I asked for the tracking number I was told it was not store policy to give out this information?? The power supply ended up coming on Thursday, and I was not home which required me to make a trip to the post office on Friday to sign and pick it up. Let me get off my soapbox and get back to the power supply repairs.
I found this great site online regarding Astron power supply trouble shooting and repairs. This document really helped me with the trouble shooting and eventual repair of the power supply. There was another online article I came across regarding how Astron now and then has the negative terminal grounded to the case of the supply.

New bridge rectifier

The part that I had to replace was the Bridge rectifier but I also ordered some heat sink compound as this was used between the Astron case and bridge rectifier. I also removed the two pass transistors and replaced the heat sink compound there as well. As mentioned above some Astron power supplies have a wire going from the negative terminal to the case ground. I read the information (seem link above) regarding Astron sometimes grounding the negative terminal to the case of the power supply. My power supply was wired this way and I decided to remove this jumper wire, if you have the same situation with your Astron supply read the article via the provided link above and make your own decision.
With the new bridge rectifier installed and wires re-soldered, the pass transistors back in place and finally I did remove one connection of the Varistor to test it (tested ok) I had to also re-solder that back on as well. It was now time for the smoke test.......and I was pleased that no smoke was found and the power supply is now working without issue. I did connect it to the Icom 7610, adjusted the power to 50 watts and the power supply successfully passed the load test as well. This power supply is under sized for the Icom 7610, I now have a new Astron power supply that is sized correctly. I am now wondering if I should keep this supply or sell it?

Passed load test

No lack of action

The CQ WW DX  CW contest this weekend was the first contest as VE9KK unfortunately, most of Saturday and into the evening I was not feeling well at all. I gave the contest an off and on again effort during this time. Sunday was a very late start as I wanted to get my rest to get over this bug I had.  In summary, the weekend went as follows:

        Band     QSOs     Pts  ZN   Cty  Pt/Q
           7       6      18    3    5   3.0
          14      10      29    6   10   2.9
          21       2       5    2    2   2.5
       Total      18      52   11   17   2.9


            Score: 1,456

I found Sunday to be a tough one my signal was just not being heard and I am guessing it was just the propagation? The few times I was on the radio on Saturday I had no issues making contacts. Some of the bonus things here at VE9KK were:

- The new Astron power supply worked just fine. 

- I was able to work Europe on 40m which never happened at the old QTH with the MFJ 1788 antenna. 

- Speaking of antennas it was a joy to use the End fed antenna, I was able to change bands without returning. The magloop I used for so long had to be re-tuned on the same band and for sure on band changes. 

- On Saturday (when I was on) I was able to get into Europe, Central America and South America without issue. 

During my time on Sunday during the contest I was greeted with an on screen message that N1MM+ stopped working as it was not able to communicate with com3. Com3 is my CAT control for the Icom 7610 and in a nutshell, this meant I was having RFI issues with one or more of my USB cables. I thought I had solved this issue already with snap on chokes?? I had a fast glance at the snap on chokes an noticed some had "un-snapped". I shut things down and spent well over an hour to fix the situation once and for all!! More on that later this week in another post. I restarted the rig and software and did a few tests and I was good to go, but the bands did not seem to want to co-operate. Having said that the bands sure were alive with opportunity. I heard nothing from the south pacific or Asia. Overall, I had a great time while in the chair at the radio and am looking forward to other CW contests. 

Defective part

The power supply troubleshooting is all done and tomorrow I will order the replacement parts, but first, there were two things I mentioned in the last post I wanted to correct........

1. I am recently retired and I was told you would slowly forget what day of the week it was, well that has not happened as of yet. I can say that with regards to ham radio contesting this retiree has mixed up what contest was on what weekend! In my last post, I had the idea of the CQWW CW contest was on this past weekend and in fact, thanks to my fellow bloggers I was informed it is next weekend. When I went back to the ham radio contest calendar site it sure was plain as day that in fact, it is next weekend. This is a good thing because my new Astron power supply will be here and I will be good to go for the contest.

2. In my last post, I indicated the varistor was defective and posted a picture of my Fluke meter indicating OL. DUH.....this is an indication the component is just fine!

Pass transistor testing

Now the power supply troubleshooting is done and I have to thankfully replace only one component and again the failure of the power supply is my own fault. The power supply is an Astron RS 20M and it is rated at 16 amps continuous, this has been just fine when I was operating QRP at my previous  QTH. As my readers know I am now retired and have moved to New Brunswick and my new antenna is an Endfed. I have been raising the power output of the 7610 slowly and slowly but forgetting I am only using the RS 20M power supply!! The result was a failed power supply as it was just not rated for what I was attempting to do.  The new Astron power supply has a 25 amp continuous rating and the Icom 7610 is rated at 23 amps continuous so I will be good to go.

Back to the final power supply troubleshooting, I checked the 2 pass transistors and they both passed. I then checked the balancing resistors connected to the emitter of each pass transistor and they were both good. There were some capacitors that I also checked and they too passed. It seems that the only component I need is a bridge rectifier along with a tube of dielectric paste for the pass transistors and a new bridge rectifier. I am very happy the repairs are minor to the power supply.

Positive test results

Just like every other morning, the alarm clock went off at 7:30 and I made myself a coffee and then sat down at the radio to see how 30m FT8 conditions were. As always I turned on the Icom 7610, the PC and then started JTDX software. Everything seemed to be as it should be until I tried to transmit my FT8 signal into the pool. My radio went into transmit but no power output, now in the past I had the power on the Icom turned down to zero and it was a matter of just adjusting the power. I checked and the power was set properly but something was wrong. I then oped the settings tab in JTDX and looked at the audio sub-tab to my surprise the audio input and output selections had changed. I could not see in the drop-down list my Icom audio selection in either the playback or recording tabs? When all else fails with a PC shut down and restart! I checked the playback and recording tabs and now there was an Icom Codec selection but why was it gone, why did it change in the first place and finally what happen to the custom names I gave these selections? I have no idea why JTDX changed the audio selection and why windows removed the Icom recording and playback selections and then they returned but the custom names were gone. All is back to normal and JTDX is functioning just fine but it is very frustrating when these anomalies happen.