Showing posts with label repairs. Show all posts
Showing posts with label repairs. Show all posts

Sunday, August 20, 2023

Productive day

I had a good day yesterday. After I finished the grocery shopping and yardwork, I was able to grab a short catnap before my weekly Skype session with Bob W3BBO.

Afterward, I went down into the shack and installed one of those new S40A1 diodes that I had ordered for my Astron RS-35A. After soldering the wire back on and installing a new fuse, I crossed my fingers and hit the switch. The fuse didn't blow, I heard that satisfying hysteresis hum and measured 13.65 Volts at the output terminals. Huzzah!

That inspired me to put the KXPA100 back in line. Surprisingly, I remembered how all the cable connections went and everything seemed to work fine - for a few moments. And then came some agita.

When I would try and tune up on 20 Meters, I would get an "ANT FLT" - antenna fault error on the KX3 display. The receive went dead - everything remained on, but I couldn't hear anything on 20 Meters. I checked the other bands and they were fine. I went back to 20 Meters, took the PA offline and everything was perfect! 

What the heck?

It turned out that when I would switch the KX3 over to 20 Meters, for some reason unbeknownst to me, and perhaps only to God, the KXPA100 would switch from ANT1 to ANT2.  I only use the ANT 1 input and I switch between the Butternut HF9V and my W3EDP using an antenna switch. This makes it easier to disconnect antennas before a thunderstorm. I only have to disconnect the coax going from the antenna switch to the back of the KXPA100 instead of disconnecting two antennas from the back of the amp. It was a simple matter of hitting a button on the front of the KXPA100 to make sure I was on the ANT1 input. From there, I switched to the other bands, and then back to 20 Meters to make sure the amp stayed on ANT1 and did not change over to ANT2. Success and a sigh of relief!

The beauty of the KXPA100 is that it allows me to stay at 5 Watts all the time. ONLY when I increase power output above 10 Watts does it kick in and go to work. However, it has the same internal ATU as the KX3 and as long as it is powered on, the KX3 will use the KXPA100 ATU no matter what the power.

That done, I worked four POTA stations, including EC1R in Spain on 20 Meters. I tried calling him with 5 Watts several times with no answer. I then dialed the output up to 50 Watts and was answered, first call. I got a 559 report and I gave him a 579 report.

It's comforting to know everything works. 

72 de Larry W2LJ

QRP - When you care to send the very least!

 

Thursday, August 17, 2023

Memories

I have no idea why this memory popped into my head while driving into work today. Maybe it was because I had the VHF/UHF on in the background and I was half listening to a Ham radio conversation.

As I was driving, my mind drifted back to all the trips I made to the Heathkit store back in the 80s. There was one on NJ State Route 35 down in the Eatontown area, about 25 miles or so from home. I would go there to get a "real life" look at all the stuff in the catalog. I spent a lot of time drooling there.

Eventually, I saved up enough money from my job to order a SB-104A transceiver I think what drew me to the rig most was that it had a feature, where at the push of a button, the power amplifier transistors were taken out of line and the unit became a 1 Watt transceiver. Shades of things to come, eh?


I spent a lot of hours building those circuit boards! After I got them done, I started inserting them, one by one, onto the main chassis as per the manual. When I got to about the third one, when I inserted it, the rig would go dead. It would just turn off. Take the board out, everything was fine.

I checked that board from ground to Heaven a million times. I couldn't detect any misplaced components, any solder bridges .......anything! I followed the troubleshooting procedures in the manual until I was blue in the face. I couldn't figure out what was wrong.

Back in those days, Heathkit's famous promise and tag line was "We will not let you fail!".  I admitted defeat, packed up everything into the shipping box and brought it down to the Heathkit store in Eatontown. I had built dozens of Heahtkits by this time with nary a problem. This was my first (and as it turned out, only) failure.  

I brought the box in, explained to the Tech what was going on. He gave me a receipt (back in those days, everything was still done on paper) and told me to call back in a few days. And so I did. He told me to come back the following week. I was working at the camera store at the time and I had to work Saturdays, so Monday was my day off - perfect day for another trip to Eatontown.

When I got there, of course my first question was, "So what did I do wrong?" and much to my surprise, the answer was "Nothing". The look on my face must have been one of astonishment, so the Tech explained to me that the fault was actually in one of the factory pre-built boards that were part of the kit - and that when I inserted my board in, the problem manifested itself.

Apparent to him, not to me!  This was before my deeper education into electronics that would come a few years down the road. My troubleshooting skills at the time were not up to snuff. I expected the Tech to bring out my box with the fixed board and all the rest, wish me good luck,  pat me on the back and send me off on the way back home. To my further surprise, he came out from the repair area with my SB-104A totally finished and aligned! He told me that since it was a factory fault, the least he could do was complete the assembly and alignment process - gratis!

Wow! Fast forward some 40 years, and I'm not sure if there are many companies that would stand behind their product like Heathkit used to. I went on to build many more kits, including some non-Amateur Radio ones, like their professional stereo system. When their Master Builder program began I had way more than enough kits under my belt to qualify.

A few years later, I think it was 1987, I had graduated from DeVry with a degree in digital electronics and was working at Sinar Bron doing electronics repairs on studio strobes. I wasn't getting paid what I thought my skills were worth, and I started looking for a better paying job. I found one at a DoD contractor, to build circuit boards for the guidance systems inside cruise missiles. 

After the interview, I had to undergo a "soldering test". I was given components and a schematic diagram and I had to sit down and assemble a circuit board under the watchful eye of an officer from the United States Navy.  After I finished, he looked at the circuit board and asked me, "Where did you learn to do work like this?" and of course, I answered (with a smile) "Heathkit!". 

I was offered the job on the spot, but there was a caveat. It was explained to me that since this was a DoD job, if there were any military budget cuts, as last one hired, I'd be the first to go. I was thinking that the Reagan years would not last forever, and add to that, the commute from home would be expensive and a traffic nightmare, and that ultimately, the job didn't offer that big of an increase in pay to make it worth my while to accept.

The bright side turned out to be that the HR person where I was working found out through the grapevine that I was looking for a better position. She went and told the boss, who in turn promoted me to Service Manager, along with the increase in pay to just around what I was hoping for. I would stay on at Sinar Bron for another 20 years.

Thank you, Heathkit!

72 de Larry W2LJ
QRP - When you care to send the very least!

Wednesday, August 16, 2023

This was the culprit

 In my Astron RS-35A power supply. The symptom? Fuse blows as soon as you hit the power switch.


The culprit is one on the two main S40A1 diodes. Right now the one I removed is nothing but a fancy piece of wire. When you test it with a VOM, you get a reading of a direct short in both directions. Fortunately the other one is okay.

I'm going to order more than one, probably three. Not only is it good to have spares, but if I purchase just the one, the shipping costs are almost equal to the price of the diode! The version I took out of the power supply was rated for 800 Volts - the version I was able to find online is rated for 1200 Volts, so I should be fine, just fine.

Last time I had the same symptom in my 15 Amp supply, it was that one of the pass transistors had failed and shorted. I actually checked those first in the 35 Amp supply, but they all tested fine. I have an ample supply of those on hand should the need ever arise to replace one of those again.

By the way, if you have an Astron power supply that is broken and needs troubleshooting, and you're a neophyte to electronics repairs and have no idea where to start, may I recommend these two documents?



I left Sinar Bron 16 years ago this past April after a 22 year stint there. That was the last time I did electronics troubleshooting on a daily basis. This was a rather simple job, as linear power supplies are not that exotic. It was nice to see that I still have some of that ol' touch, and that the skills, instincts and thought processes are still there. Office work tends not to be as "stimulating", shall we say? I mean there's a bunch of problem solving and mental agility required, but it's not like knowing how to read a schematic and getting your hands dirty, and knowing in the back of your mind that you're dealing with some extremely high, and even lethal voltages. That requires a certain edge.

72 de Larry W2LJ
QRP - When you care to send the very least!

Sunday, July 03, 2022

I make fix!

There was time today to head down to the basement shack and put the MFJ-1982LP antenna on the bench. This is the antenna that failed for me during Field Day - in the middle of the night (strains of Billy Joel in the background.) How does an end fed antenna go bad? I guess there are a number of ways so I had to eliminate them.

1) The wire itself was not damaged, kinked, cut or otherwise disturbed along its entire length.

2) Opening the UNUN box the toroid looked fine. No cracks, no breaks, again ..... no mars.

3) The toroid windings were of a stout gauge of enamel coated wire - no breaks or other visible defects.

That left two things - either the two capacitors in there shorted out, or one of the factory performed solder joints was dicey.

My gut went with the solder joints. Nothing was to the point of being loose or hanging free, but it looked like whomever soldered the joints thought that solder was going for about $200 a pound. The solderer could have been way more generous with the stuff.

I heated up the ol' Weller, added more solder to ALL the joints and headed out to Cotton Street Park, my home for the NJQRP Skeeter Hunt.

The first thing I did after setting up was to bypass the ATU in the KX3. A brief hit of the tune button showed about a 1.2:1 match on 20 Meters. No more infinite SWR readings!

As long as I had everything set up, I decided to work a few stations. First up was AC6ZM on 14.044 MHz. He was at POTA K-7605. I haven't looked up where that is, I'll do it later.

I know I said I wasn't going to bother with the 13 Colonies Special Event, but they provided such a target rich environment. Perfect for giving a repaired antenna a workout!

I worked TM13COL on 20 Meters, making it through the pile up with 5 Watts. Then I switched to 40 Meters and worked K2E is Delaware and K2M in Pennsylvania. I finished the test back up on 20 Meters by working K2G in Georgia. The op was Phil K3UT and he must have recognized my call as he didn't send that bit of info to anyone else he was working.

I listened for a bit on 15 Meters but didn't hear anything, so I packed up my hastily erected setup and returned home. It's a comfort to know that I have the antenna back at my disposal. However, I'm still going to set up a backup antenna next year at Field Day - bitten once, twice shy.

As far as 13 Colonies goes, that was enough for me. I'll let the newer stations or those who have never gotten a clean sweep have a go at it.

72 de Larry W2LJ

QRP - When you care to send the very least!