This is an old Galaxy DX-44V 10M mobile rig where a few too many too many screwdrivers had been in. The final output transistor was shot, and the radio was totally out of alignment. Once that was all corrected, it was up and running nicely. Here's vids and pics...
I've been in Amateur Radio since 1974, and still find new and interesting things to do. I like to build, restore, and operate on the air. This blog has been running for many years, so be sure to check out "Jump to Posts on Specific Topics" in the RH column to drill down and find lots of stuff. Visit www.WB4IUY.net for the lowdown at WB4IUY. Email me at wb4iuy@gmail.com if you have any questions.
Saturday, August 31, 2024
Kenwood TM-741 Repairs
This is a Kenwood TM-741 tri-band mobile. These were way ahead of their time, when they came out in 1992. It was connected to an antenna when a near lightning strike made it deaf on 220. The owner put it on the shelf for many years, then it came to me for repairs. During it's downtime, the memory battery failed and several caps started leaking. I replaced the battery, recapped the motherboard and all 3 band modules, replaced a FET in the 220 module, repaired oxidized connectors on the band modules, and got it back on the air. Here's a couple of vids and pics...
MFJ-752 Audio Filter
This is a MFJ-752 active audio filter I modified for a friend. It originally comes with a 1/8" phone plug for power, and is unfused. I added a fuse holder and DC power pigtail for connection to his shack DC supply. He also wanted a 1/8" audio out receptacle for his shack speaker, so that was added in parallel to the OEM 1/4" jack on the back. These are pretty slick filter units! Here's a few pics...
Tuesday, August 27, 2024
Concrete Pumping Truck Cable Problems
This is another project from a concrete truck...concrete is a pretty strong alkaline, and can wreak havoc on electrical wiring and electronics. Here's an example... this is the cable that connects one of the remote control systems to a remote concrete pumping truck. It began having multiple intermittent problems. Upon inspection, I found lots of loose and rusted/oxidized connections, and one connection that was completely eaten away. After cleaning and repairs, all was well and back at work.
Yaesu FT-897 Memory Problem
This is a Yaesu FT-897 that began to loose memory settings, then quit booting properly, altogether. These use a EEprom to store radio settings, so there's no memory battery to fail. It was booting with everything turned off, most menu settings at 0, even the screen backlight was off. After a bit of searching, I discovered the processor could not access the EEprom memory chip due to open circuits on the PCB. I reflowed the processor and memory chip, with some results. Then, I used a low temp soldering iron with the tip turned down to a needle point, and resoldered a few stubborn pins. Here's a few pics and vid:
Video of problem area around processor and memory chip: https://youtu.be/EMsgt9_ojPg?si=0Wr08l2lrCplcYUw
Video after completion: https://youtu.be/-IsJuM0JImc?si=a1V2xQUU5NuW3_J9
Another Computer Overheating...
This is another old, overheating, junker computer of mine. I mostly use it for viewing schematics in the shop. Processor power isn't too terribly important, it just needs an O.S. that's new enough to download schematics from a few archive sites.
Recently, it started shutting down if I began expecting multiple pages to toggle between, and it was showing overheat when I peeped at the bios screen.
It spends most of its life standing on end in a small gap between cabinets. I pulled it out, popped it open, and found quite a bit of dust.
It uses a heatsinking system where a manifold is clamped to the processor, a copper tube then conducts heat over to a little "radiator", and a fan blows across that. The heat sink compound had dried to the consistency of baby powder, so I cleaned and replaced that. The fins on the little radiator were packed with lint, so that was cleaned.
She's reassembled and running with no problems, now. I realize that most folks would have put it in the trash years ago, but it still serves a purpose and is out of the landfill :-)
Sunday, August 25, 2024
EF Johnson Messenger 223 Restoration
Here's another yard sale find...I can't help myself. This was one of the dirtiest, worst condition rigs, I've done in a while. It had set in a damp barn for decades, and the chrome had bubbled up a little. I'm still looking for a junker with a good knob and decent faceplate, but it's pretty good, otherwise. After a major cleaning, I replaced all of the electrolytic caps, a bunch of resistors, removed a dirt dobbers nest, and aligned it. Wow!! What a hot receiver this old girl has. Another classic saved from the landfill, and on my shelf in the collection. Here's a few pics...the first 3 are post resto, the rest are of this dirty beast during resto. Check out the dirt and caps :-) How do radios get in this condition? I guess I love radios too much!