Category: My Equipment

Until Sunday. Earlier the day I worked the Unions End expedition organised by the Adventure Radio Club [click here fore more info] under the callsign ZS3ARC on 40m. It was busy but I didn’t have any trouble to exchange 59’s with Martin ZS1SM and so I was quite chuffed with myself, adding the very rare grid square KG05 to my slowly growing WAGS collection.

Later that evening when the bands closed and they moved to 80m I thought it would be nice to make a second contact. More is better, right? So I called Martin. He was happily chatting away to some other contacts so the band must have been relatively open to him. Here and there he mentioned crashes or interferences but generally he was having good QSO’s.

So I called Martin again. This time I checked my equipment casually just to make sure everything is plugged in and so on. Martin chatted on …

The third time I called Martin he heard something through the noise but he couldn’t properly identify me and stuff, and we couldn’t complete the QSO. By now I realised that this logbook entry was going to take something a little extra, like a few extra WATTS.

Earlier this year I bought a HLA 300 Plus amplifier made by RM Italy from Sams Radio. The price was right, my power supply wasn’t. On a good AHH! it pulls more than 40 Amps and trips my 30 Amp power supply. However at that stage it already bends the needle on my SWR meter past the 300 Watt mark. So the little project was paused, waiting for the arrival of some shekels to upgrade the power supply. And while I was waiting I was happily adding more countries to my logbook using the 50 or 100 Watts of the barefoot radio.

But getting this grid square twice was very very important to me and so I decided to take a big risk. What if I kept my voice lower not to exceed the power limit? Very quickly I plugged the antenna across, the amplifier was already wired to the power supply. I went right down to 5 Watt on my Yaesu FT-857D, I switched the 3dB attenuator on the front panel of the HLA-300 in, tuned 10kHz lower in the band, and did a test call. Disaster! The power supply crumbled under the strain. I will not forget the disappointing click of the trip switch. Sigh. What now!

My antenna is a 80m horizontal loop strung between the trees and it resonates slightly higher up in the band. I pulled out my MFJ-941E Antenna Tuner (also from Sams – thank you Sam!) and pulled the obviously too high SWR down to something a little bit better. By now I was panicking and my hands were shaking so I remember that my settings were not perfect. Next time Sam, please sell me the automatic tuner version! A last check that I’m not connecting the wrong coax cables, and I sit down for a final test. If this doesn’t work …

Just over 30 Amps and 240 Watts and she holds! Lets go! Tune to 3.680 MHz, check my breathing, and wait for a gap. One call (with my eyeballs firmly locked on the ATU power meter) and Martin comes back! Yippee! He gives me a 57 because of QSB and noise but a very readable signal and we both confirm our entries in our logbooks! Crazy how happy I was with that contact confirmed!

But the basic root-problem remained a high frequency noise on the audio, especially on 40m, that made it very unpleasant, difficult and tiring to listen to.

I invested in a MFJ-784B Tunable DSP Filter to see if it made any difference. It was nice to play with and I will write more about it later, but sufficient to say it doesn’t get rid of my problem. It improved the average sound but the high frequency annoying fuzz was still there.

So yesterday I bought a dhi DSP Amplified Module (NEDSP-1062 KBD) and rushed home, prepared to be dissappointed again. I rigged up a lid from an old CB radio and tagged and taped everything together to try it out before deciding on a more permanent installation (remember, it might not work). Well, 4 hours later and many delightful QSO’s in the log I can honestly say: “It works!”. You can believe everything they say on their websites, and all the audio clips they give are exactly as I experienced it on my bench.

Essentially the kit I have (there are others too) sits in the speaker line. The 1062 is an amplified unit that takes speaker output, processes it and throws it at your new external speaker. It has multiple levels of processing and I found myself settling (after much playing) on number 5 (16dB tone reduction and 17dB white noise reduction), but I can imagine with other radios and speakers and setups the ability to easily choose more or less processing is going to be a big help.

Certainly a must-have on the Yaesu FT-857D and one that I cannot operate without. I see they make a specific one that can be mounted inside the case of the FT-857 with the buttons easily accessible on the top. I like that. I might even sell this one and buy that one. The processor is identical, it is just the mounting thats going to be easier.

Verdict? On a scale of 1 to 10, where 10 is the best, I will give it 11 because it has consistently surprised me.

It might have something to do with the fact that my first rig many years ago was a Yaesu FT-707 with tuner and PSU and everything and it served me well for many years. That is a story for another day. But back to the present: When I pulled my trusty 707 from the mothballs a few weeks ago the caps were obviously dry and the VFO danced a merry dance on the display, and fixing it was not going to be a quick-fix. So when I found that Charles King ZR5CTM had a secondhand Yaesu FT-840 he wanted to sell, the negotiations with the minister of finance started. What? she said – you already have so many radios (pointing to a broken 707). To cut a very long discussion short, I ended up making Charles an offer which was accepted and the parcel was posted to me.

Disaster! The SA Post Office kept my precious parcel for 3 weeks, claiming there was a strike and that nobody was receiving any parcels. Yet on their track-and-trace, backed up by a phone call from the missorted post office branch, it clearly showed as having been sent to the wrong place twice. When I am calm again I will tell you that story of the strike that was not a strike.

But back to the main story. Upon receiving my cargo it was obvious that it had seen a few hard bashes along the way and there was something loose on the inside. It powered on but didn’t transmit and a few other strange behaviours. Googling it pointed to a very common problem: There is a resistor R2213 near a voltage regulator that runs very hot and sometimes burns out. Well, I know Dion at LA Radio who fixes radios so off to the workshop we go. It seems that the ceramic part of the resistor can get brittle and in this case broke from the shaking around. It was a simple fix to attach a 10 ohm 10 watt resistor to the back of the chassis with two connecting wires, and voila! tha radio works like new. We chose not to drill any holes in the chassis because we didn’t want microscopic metal shavings to settle inside the radio. Have a look at our mod:

The work we did is based on the article by John E DeBarr Jr aka November Alpha Eight Yankee [click here] but we had to use another component that is locally available. Instead of a 8.2 ohm or as some other websites say 9.1 ohm we only had a 10 ohm resistor available. It doesn’t seem to make any noticable difference. I took some pictures and can send you a PDF copy of my own work as we progressed but John’s article is quite clear with some very good instructions and pictures, for example this one shows the old resistor still in position (mine was broken):

My 10 watt resistor hanging off the back of the radio gets very hot, so I can imagine what the original puny 3-watter must have felt like inside the radio. Definitely a recommended procedure to prevent further damage to the main PC Board.