Wednesday, 3 June 2015

Flex 1500 failed, plus resoldering everywhere

I regret to have to report that my trusty Flex 1500 seems to have died, or at least become very sick.

It takes 10 seconds from pressing the PTT to anything appearing at the output socket, and then another 10 seconds before full power is reached.

I am not sure if this is a common fault, or even if it could be fixed here in software. I tried deleting the drivers and reinstalling them, and then using a different version of PowerSDR. I then tried using a different PC. The results were always the same.

It seems to me that this is a hardware fault - like real radio. You know, output devices and things. Not software. My only nagging doubt is the Flex firmware. Flex offer an integrated firmware/software installer, and I hope that the re-installation using a different PC would work to solve that one.

Anyway, after a couple of days fiddling around with it, I rang the UK distributor for help. They told me that their "Flex expert" had left and I would need to send it to Italy. They gave me the details of someone (in Germany?) who might help, so I have emailed them. We shall see.

Meantime, trusty HF rig number two, the Yaesu FT-817, is doubling up between 10m and 6m. This is not quite satisfactory as I only have a couple of watts at my disposal. In fact, I have to run 2 watts on both 6m and 10m, whereas I usually run either 200mW or 20mW on 10m. It is hopping between bands on WSPR so it does not cover both at once, and, hey, I want to listen on both.

At this point I will digress onto how I work VHF at this time of year. I have a separate rig on each of three bands. That might seem crazy, but most of the time they are just listening. So I have the following combinations available - the FT-817, the Flex and the IC-7100. The Flex does not cover 2m, but the other two do, and with the ME4T transverter for two of them, they all cover 10m (honorary VHF), 6m and 4m. Simples.

I only have two ears, but then 10m is usually covered by WSPR, and so is 6m most of the time. 2m only comes into play from time to time, and not often during the Summer (it seems to be a meteor scatter band for me now).

So not having the Flex is a blow for now. I hope it can be fixed at a reasonable cost. I would feel sorry to lose it, but let us leave that idea for now.

After having a problem with the 6m antenna, which turned out to be both a faulty SO-239 socket and a faulty PL-259 plug, both at the same time, I decided to do a health check on all patch leads. Yeuch! What a mess they were in.

I found that quite a few solder joints were failing through corrosion and age. The basic problem seems to be in the plugs. At one stage, when I was more of an HF operator, I took more or less any patch lead. I matters more at VHF.

Several of these leads are commercial. Sometimes, I bought them to save time. If I saw some at a good price I bought one for the spares box. Always handy when you need to bodge up a test on some new antenna or something. But many of these have failed.

Not just the joints, but the plugs too. All I did with this one was screw the co-ax up into the plug, and the plug fell apart. How that was supposed to work I have no idea, and I bet the impedance was pretty random.

I found one patch cable which I cannot ever remember buying. I could hardly have made this one myself. It must have arrived with some second hand linear or something. The coax seems to be of the unknown "CB" variety. The braid was barely making contact with the barrel of the plug. The plugs were too wide to grip the outside of the coax. A quick test with the multimeter indicated a high resistance joint in the centre strand of the coax. One plug fell to pieces.  The other plug had a blob of solder which was loose in the pin, but too wide to pull through. I could not be bothered to unsolder it, I just cut it off and binned it.

I have no idea why I decided to keep the coax and save this lead. I just cannot bear throwing away something, even lousy co-ax. I found a compression 259 which fitted one end but I only had one. All my pugs were built for thicker co-ax (no surprises there then). Hunting through my "can't bear to throw things away" box, I found an old PL-259 with an inch or so of cut-of co-ax. It was small enough in the barrel to grip this thin co-ax. So I unsoldered that and refitted it.

Tah - dah!!! A refurbished patch lead, with nice grippy plugs and low resistance joints. And it uses crap co-ax which confines it to the "emergency drawer". Someday I will replace the co-ax, thus preserving my investment, but with a lead that has two new plugs and a new piece of co-ax. Not any part of the original will remain.

Anyway, all other leads have now been checked and "re-certificated".

I heard it said that you can tell the difference between a radio amateur and a professional radio engineer, because hams re-use their plugs and leads, whereas professionals throw them away after one use. I bet they are made for one use.

I find that the only PL-259s which work on multi-use patch leads are the ones with plastic rear sections which grip the coax firmly. Otherwise, constant use unscrews the coax and they fail. Or you make your own, solder the braid properly or use compression plugs.

NO SHORT CUTS HERE, you know. I am famous for my quality soldering.

73

Jim
GM4FVM

No comments:

Post a Comment