GM4ULS ham radio station

a QRM-free zone!

1] My other hobby is blowing up linear amplifiers. 2] Reprogramming the AT-5555

Posted by gm4uls on June 25, 2012

What is it with me and linears? Another one just bit the dust, and I swear all I did was give it three seconds of SSB with minimum input power. Yes, the RM KL 203-P has gone phut. I have no idea what happened – I ran it for three seconds without the pre-amp on (because frankly it’s unnecessary), and when I let go of the PTT there was a ‘swoosh… swoosh… swoosh’ sound and the RX on my AT-5555 went quiet. I switched the 5555 off and on and normal RX was restored, but although it would allow transmitted and received RF through, and although its LEDs lit up, there was no amplification on receive or transmit. That means two Zetagis and one RM have failed here under minimum operation. Put that together with the flash-over on the FL-2100Z, and I think someone somewhere is trying to tell me something about linear amps…

Anyhow, on the plus side, I spent the whole of yesterday reprogramming the AT-5555. Here’s what the software display looks like on my Toshiba laptop (800 x 600 resolution).

‘Tree’ view of AT-5555 software screen

It was one of those little jobs which take all day. the first hurdle to jump was finding driver software for the USB connection. It’s an ATEN USB to serial bridge, but without the driver the rig and the computer wouldn’t talk to each other. I found some software without too much trouble, after being taken ‘all round the houses’ on some dodgy-looking sites who wanted me to download all kinds of things to ‘speed up’ my PC, and eventually facilitated a conversation between the rig and the computer.

The software could do with a more help in the ‘Help’ section – like teling you how to use it, for a start! All you get is an ‘about’ box, and there isn’t a lot of ‘about’ in it. The most frustrating thing was not being able to display more than 26 channels on the screen. No matter what I did with the scroll bar(s) to the right, it would not go beyond 26. Having 60 channels per band meant that I was getting mightily disgruntled. There is a way, however. If you go to the ‘View’ command on the menu bar, you will get a drop-down menu. Un-tick the ‘Tree view’ option and a view comes up which does allow you to scroll down to channel 60.

Connecting the rig to the laptop means removing the bottom part of the case. If you are handy with tools I suppose you could mount a socket somewhere, or lengthen the lead to the jack plug and have it as a ‘flying lead’ coming out of the case. However, ‘he must needs go whom the devil drives’, as Shakespeare put it, so I opened up the case and got to work. I might add here that if, like me, you had to wait for your software and had meanwhile mounted your AT-5555 somewhere, opening the case involves un-sticking the adhesive pads that protect the rig from being scratched by the mounting bracket. There is no guidance (wouldn’t you know it!) as to where to stick the tiny white plug, but there is a tiny white socket mounted directly onto the main PCB – sorry, I should have taken pictures. The plug is a tight fit, and when I had finished the whole process I had to ease it out gently, worrying about loosening something on the PCB.

The software has the facility to ‘read’ from the transceiver and to provide a display of what channels are already programmed. Also, of course, it has the facility to ‘write’ to the radio. While either process is going on, the main display of the AT-5555 shows ‘PC’, and when it has finished it shows ‘End’; it is necessary to switch the rig off and on again to show frequency again.

I think if you don’t ‘read’ from the rig you are presented with blank pages on which to input your desired channel data. That’s easier, because all the various columns fill up with default settings every time you enter a frequency in the first column and tab out of it. Tabbing, however, does not seem to move you anywhere, and you need to click into the next box you want to fill. I did ‘read’ the rig’s channels. One result of that seemed to be that when I came to enter new details I had to type each new receive and transmit frequency into the first two columns, which was rather laborious.

All the other columns should be left at ‘disable’. This doesn’t mean that, for example, if you disable ‘RB’ you won’t be able to switch on your ‘roger beep’ via the button on the front panel, it just means it won’t be set to come on as a matter of course. Each box has a drop down option of ‘Enable’ and ‘Disable’.

When you have all the frequencies you want, go to the ‘File’ menu and select ‘Save’. That will keep a record of the settings you have chosen, and if anything goes wrong with your rig you’ll have them there ‘on tap’. The very last thing I did was to go through each channel on the rig to see that everything was correct. I’m glad I did, because by accident at least one frequency had been typed in wrong, and three channels had defaulted to Echo. Always check before disconnecting and screwing the box shut! Any amendments can be saved.

I now have all the 10m repeater channels within a single band, and the FM calling frequency and FM/AM simplex channels within a single band. I also have RX capability on some of the US/CEPT CB channels – in particular ‘triple nickel’, 27.555 MHz, the USB calling frequency – in order to be able to keep an ear on 11m propagation. Often it seems to be open at 11m and quiet at 10m, buzzing just below 28MHz but no CW signals just above, lots of CQs on 27.555 but nothing heard on the 10m beacon sub-band.

Without the linear amplifier I only have about 10 or 12 watts on 10m AM, but if propagation is good, that should be enough to resume my transatlantic contacts, I hope. We’ll see.

2 Responses to “1] My other hobby is blowing up linear amplifiers. 2] Reprogramming the AT-5555”

  1. Hans said

    Maybe this can be of some help:

    The “Testing Transistors” could shed some light on the problem. I never had Zetagi / RM stuff here (or any solid state amp, for that matter). So I can only guess here, but unwanted oscillation is not unheard of.


    • gm4uls said

      Thanks Hans, I’ve had a little look at that page and will bear it in mind for future perusal at leisure.

      There is also the old saying – “You get what you pay for”.


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