Posts Tagged ‘Trouble shooting’

One of those “Are you kidding me” mommets.

Back in late April, I posted the inspection of two heat sinks my Icom 7610. I always get a bit anxious when I remove all the cable from the radio and all that is plugged into it. In the past, I have learned that it saves lots of time and headaches if I use my trusty iPhone and take pictures of the cabling. I really don't have all that many cables at the back of the radio BUT I still take pictures. Once the heat sinks checked out to be without issue it was time to re-connect the radio again along with my trusty pictures.
All was connected and it was time to fire up the radio and see what happened. Everything was good and now it was time to make sure all software was "talking" to the radio. There were no issues so far until I went into transmit. The antenna I am using is an EndFed multiband and I do need a tuner to allow a decent SWR. The odd thing was it seemed my tuner lost its memories of the presets for each band. That was no issue I just started back at square one and returned each band so it was in memory. The issue was after tuning the band I would attempt to transmit and the tuner would start tuning again as the SWR seemed to go back up over 3.0. The first thing I checked was that the antenna was still up and it was as you never know stuff happens. I double-checked the rear of the radio with my pictures and all was good there.
To me, it seemed something was up with either a coax patch cable or the coax out to the antenna. The first thing I wanted to check was the PL259 connectors on the back of the radio. I have in the past had these connectors show issues once they were moved around with being unconnected and re-connected. I try to keep coax angles very slight as I have found over time this can add stress to the connection. I was not looking forward to the whole process but it was the next step that had to be done.
I am not sure why but out of the corner of my eye I noticed my LDG DTS-4 antenna switch which I use as a radio switch (between my Icom 7610 and Elecraft KX3) and not antenna switch as I only have one antenna at the moment. The light on the DST-4 position 1 for my 7610 was out and the light for the KX3 position 4 was on! Problem solved the DTS-4 was grounding out my 7610 as it was not selected and with the simple push of a button my problem was solved.  

The Astron RS20-M repairs completed

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

WHAT an SWR of 99:9!!

The other evening I had an opportunity to get on the air it has just been to long and I was very excited about spinning the dial around the HF band! I ran the coax out to my MFJ 1788 on the balcony and fired up the K3. I jumped on 20m were not to much was happening but on 30m there was some Dutch DX that was calling CQ so I thought I would give them a go. Prior to calling my SWR on the loop antenna was tuned to 1.2:1 BUT when I started to call the Dutch station my SWR readout on the K3 magically became 99.9:1!!! It was like the coax had been removed from the antenna and was sitting on the ground. It was late so I wanted to look into this at a later time, this evening was the later time so I hooked the antenna up and gave 20m a go and the SWR once again on the K3 was showing 99.9:1. It was time to trouble shoot, was it the coax, MFJ 1788 antenna, the K3 or my LDG antenna switch? The first thing I wanted to do was to remove the antenna as the problem.
Without LDG antenna switch
I removed the coax from the antenna and in it's place put a 50 ohm dummy load. In a way I was relieved to see the 99.9:1 SWR thus removing the MFJ 1788 from the problem. Next I bypassed the LDG antenna switch and low and behold the SWR now was 1.1:1 and me saying thank god it was not my K3! So it would seem the LDG  antenna switch is the problem so I took the switch cover off and looked around. I cleaned the SO-239 connectors, check the internal connections and all seemed to be great. The only problem spot to me could be the switching relays with internal contact troubles? After exercising the relays the trouble in the LDG antenna switch seemed to be ok. If the trouble comes back this is a 4 position switch and I only use 2 positions I could swap out relays and look at ordering all new relays. At this point all seems to be working well but stay tuned to see if relay swapping and ordering is in the near future.
Relay in the LDG antenna switch

Water + PL-259 = no radio for the day!

The waterlogged  PL-259
Well FINALLY I was able to get some radio time it has been so long and really there were no good reasons just what I call excuses!  On Saturday afternoon it was time to get some long over due radio time in. I ran my coax jumper  to the 1788 MFJ loop from my K3 radio, I settled into my radio chair and flipped the switch…..and……it was time for Murphy to visit me! With the MFJ loop you are supposed to tune the loop for peak noise and this was just not happening. I was getting numerous peaks but the SWR was all over the place! I thought about it for some time and after trying numerous ideas it finally hit me! I have a 6 foot coax tail on the loop and via a coupling I connect the coax from indoors. It was really raining the last few days and the balcony was very wet and "normally" my outdoor coax tail is in a plastic zip lock bag. This past rain storm was also accompanied with a strong wind and somehow the coax was removed from the bag and was in the water. I removed the coax and checked it with my ohm meter and it showed a high resistance between the centre conductor and shield. So it seems water has made it's way into the PL-259 connector and after installing a new piece of coax and doing some check with great results it was time for bed. My loop is supported by the MFJ tripod. I have a cover over the loop it to help disguise it and kinda makes it look like patio furniture. There is lots of wind being high up and on the lake so the cover has to be secured around the centre pole of the tripod. It's great that the antenna works perfect with a cover and with it secured as well I just want to come up with an easy way to connect and disconnect the coax from the antenna. I don't want to remove the cover or un-secure it from the centre pole. Any ideas from ham world would be approbated.
A shot of the balcony antenna open for suggestions. 

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