IC 7000 usual failure!

I have just received an email from my friend Tasos (SV8YM). He describes what is the reason of a usual issue on IC 7000 transceivers and what is the cure on his opinion. Besides he will publish this mod in a proper site I think it is very important to post his whole   letter in my blog. It is not a secret that I suffered from this problem twice.

“IC-7000 driver amplifier self-oscillation problem

The IC-7000 is a very popular rig, and rightly so, since it combines many desirable features in a small, light transceiver. I was surprised when some of my friends reported that their rigs had literally gone up in smoke!
Actually, one of them had died TWICE with the same symptoms (scorched driver unit). Later I found out that this phenomenon has also been reported by other users on the Internet. The whole thing reminded me of my experience with my FT-817 (which, by the way, still goes on strong).
As I undertook to fix my friends' rigs, I decided to implement the same self-oscillation preventive measures to their IC-7000s, as the failure mode had a strong resemblance to that of my FT-817 final amplifier.The problem probably lies with self-oscillation of the common driver stage of the TX amplifier chain. A series resistance
of a few ohms is placed in series with the input (gate) of the FET amplifier, by cutting the appropriate PCB trace. The photos and schematic explain the modification. It is very simple to do, and can help prevent this "smoking" failure mode, without any side-effects and at negligible cost.

 
 

THEORY OF OPERATION: This mod lowers the Q of the copper trace circuits feeding the driver amplifier's input, therefore
quenching any tendency of the stage to self-oscillate at some VHF frequency, with destructive results.

IMPLEMENTATION: After removing the covers, locate the driver unit's input trace (SEE PHOTO), cut it carefully and scrape the solder resistant enamel to expose the copper surface. Then, solder an 10Ohm (or so...) SMD resistor across the cut of the PCB.That's all!

IMPORTANT: After you have finished, carefully check and clean all of the springy ground clips on the PCB. Also, clean  carefully and apply a thin protective film of grease or vaseline to the points on the covers where the grounding clips of the PCB make contact. The deterioration of this grounding scheme due to oxidation of the inside surface of the covers has been proposed as a possible reason for the driver unit self-oscillation and destruction.

Disclaimer: This mod requires delicate SMD soldering. Perform
at your own risk. Although the mod is based on proven engineering
techniques and worked perfectly for me, I can't guarantee that it will
work for you.

Tasos Thomaidis sv8ym@raag.org”

Thank you Tasos for all. BTW see in the photo below, how the driver unit will look like if this failure happen to you too. My IC-7000, after mod, is working perfectly so far. 

CQ CQ D-STAR

It seams that a new habit is coming up nowadays. Kohji was calling CQ in our local D-Star repeater. His voice was clear and loud without any delay despite the long distance trip through the networks. Chatting with him I found out that he is living in Hiroshima in an apartment on the 12th floor of a skyscraper. No way for any other ham activity except through D-STAR system. I did not realize before that such a case could exist. Anyway it was charming talking to him owing to new technology. 

Soon after I found his QSL card in my eQSL inbox. I wish you many DX Kohji…

Goodbye 2009

Two days left. I post this diagram as a postcard wishing you Happy New Year. It sows clearly the trend, through the whole 2009, of a recovering sun. If continuous like this, smiles will come back to the dx-ing world. More info to:http://spaceweather.com/

Speaking for dx I have just received the TX5SPA (Austral Is) qsl card reaching with this the 332 current countries. I hope for one or two more during 2010. See you next year!

SDR remote

Simon Brown (HB9DRV), the author of legendary HAM RADIO DELUXE, made recently an other interesting program. SDR-RADIO is a remote console that can control an SDR receiver remotely  through a network connection. You have all the bandwidth of 150KHz on your screen.

Denis (SV8RV) gave me the chance to test the software, controlling his SDR-IQ from my shack. It gave me   fantastic results! Everything worked smoothly. Functionality and audio just perfect. Like having the receiver next to me. This would be a really powerful tool indeed, combined with an SDR receiver, installed in a quiet site. Take a look on the snap above.

Sunspot record

Circle 24 reached a maximum SSN record today. Number 43 is the biggest ever in current circle. So Merry Christmas dear fellow hams and enjoy Santa Claus gift.

Heavy weather out of my door

As the Christmas approaches and the 2009 is going to an end, it is time to relax and enjoy the days with ham happenings. Weather is bad of course but who cares. Clouds are permanently on the sky and the storms follow one after the other. The space weather is really nice instead. Flares, CMEs, sunspots…we have almost everything but not favorable dx conditions yet. Sooner or later they will come.

Today I had a surprise, talking to Mike (SV8KOM) who is in UK. The QSO took place via D-STAR system (SV8S local repeater). D-STAR connecting people… in case propagation does not.

I wish to all of you Merry Christmas and a happy New Year with lot of dxing.

BTW TX3A  is coming first dxpedition of the year 2009 in the DX World petition. The “unbelievable couple” deserves your vote.

 

http://dx-hamspirit.com/dxpedition-of-the-year-2009/

After contest

Participating in a contest, so big as CQWW CW, it is always a great experience. Both my station and my location can not compete the big guns but it is always a nice chance to work in cw many dx entities and fill some missing slots. So I made 275 QSO working with long breaks. The 10m band was closed (only 3 contacts). The 15 was the most DX band. The 40 and 20 the most crowded.  Speaking about contest I stopped by  K3LR page to admire a real big gun. Take a look on his operating room and the huge amount of awards on the wall.

I meet him almost in every contest. Recently I got his QSL card via bureau.

As CW is not my favorite mode, I should  mention several tools that technology gives to every operator to assist him during the contest. CwSkimer is one of them. Excellent software with tremendous abilities of decoding many calls simultaneously. On the other hand reverse beacons make a great job monitoring the propagation in every band in real time. My friend Denis (SV8RV) has a station  dedicated to these projects, using the QS1R SDR receiver. Denis is living in the same island and his offer is much appreciated. Look for his reports on the sites reversebeacon and pskreporter.

After that you already know that I join every contest proudly assisted!!