This is a going to be a rather long entry and possibly only relevant to those with a Kenwood TS-2000 radio, but feel free to read on. It documents a problem I experienced and what was done to correct it, so hopefully others with the same problem might find this in search results with the info they need. I’m not the original source of all the info but just aggregating it in one place.
A week or two before I was heading out to Dayton for Hamvention 2011 I started to notice noise when using my TS-2000. At first it would come and go infrequently so I didn’t pay too much attention, but as time went on it got worse and more frequent. I initially started troubleshooting the problem as interference from something in my home or the surrounding neighbors. I spent a few hours one weekend tracking down a noise source in my house, but it ended up being unrelated to what I was hearing on the radio. The problem would show as intermittent bursts of what sounded like lightening strikes/static crashes that would push the S meter on my TS-2000 up to S9+60 and then it would go away. As time went on it would become more frequent. Transmitting was fine and when there weren’t those loud crashes, receiving was fine too. When the noise was present, I could press the +/- band buttons and the noise would be there regardless of band. I didn’t try and see if it was on FM or not.
I moved the radio into my car and without an antenna connected and on a standalone battery source I was still hearing the noise as I drove around, essentially eliminating external interference as the cause. I started to search online and through my archived emails I have as a member of multiple TS-2000 groups and came upon what seemed to be a match to my symptoms. A few folks reported the same static crash symptom with some sending their TS-2000 to Kenwood for service and some adressing the issue on their own. One op, LA4AMA, even created a great PDF file with step by step instructions for anyone that wanted to do it themselves. I checked with LA4AMA and he was fine with me posting it here
The actual problem is 1 to 3 bad filters. Maybe there was a bad batch that Kenwood received but I wasn’t paying enough attention in the various threads to determine the specific range of manufacture dates for those reporting the problem. My TS-2000 happens to be manufactured in April 2008. I’ve also seen subsequent posts about other manufacturers having a similar filter issue but I’m not sure how related their problem might be to the Kenwoods.
The parts are surface mounted and require a desoldering tool that sucks up the solder to do it right. Even if I had that tool, I’m not sure I would have taken on the task myself. So I checked with a local club member that owned an electronics repair business to see if he might be interested in checking it out, and if not I would just send it to Kenwood for repair. I sent along the PDF that La4AMA created and a couple of posts from the various Kenwood groups describing the problem. He reviewed everything and said he’d give it a shot. I ordered the parts for the 3 filters that share 2 distinct parts from Kenwood Parts aka East Coast Transistor. The 2 parts are L72-0985-05 and L72-0984-05 and each part is under $5. You need at least a quantity of 2 for part L72-0984-05 and 1 of part L72-0985-05. I ordered a spare of each, just in case. With the necessary parts, 2 spares & shipping (USPS), it came to $29. Without the spares it would have been just over $20 total including the shipping. They arrived within a week of ordering.
When the parts arrived I arranged with the very generous friend to drop them off along with the TS-2000. We discussed him checking that with the radio on at his location, he could replicate the problem so he could hear it in action and then after replacing the filters, he should hear a difference. After dropping everything off I was heading over to another club members house to operate the VHF contest that was going on. While operating the VHF contest, I got an email to call him back, and when I did, he was explaining what he was seeing/hearing with my radio. It seems since I last had it powered on (maybe 2 weeks earlier) and with moving it to his house, the symptoms had changed. The S meter was no longer moving, even when receiving a strong signal, and he was hearing no static crashes. I know there needs to be a setting (AGC) enabled for the S meter to move, and it was, so that wasn’t the problem. He also said he was hearing only strong stations compared with moving the antenna over to his radio and hearing more stations. I hadn’t seen posted in the threads discussing the filter problem about the S meter being impacted by the filters going bad.
After operating the rest of the VHF contest I stopped back at his house to see what was going on. We did a full TS-2000 reset to see if that helped, but nothing was moving the meter on SSB, even with injecting a direct signal. We were hearing more stations than he original reported, but it was still VERY quiet compared to what I normally hear with an antenna plugged in. So we decided to proceed with replacing the filters and if things were still not right I’d send it in to Kenwood for servicing. Late that night he sent me an email to say he replaced the filters, reception seemed fine, and the S meter was again accurately registering noise/signals. Woohoo!!
I’ve only had it back home and plugged in for a short while but everything seems to be working well. Thanks are due to many people from the local ham that loaned me a TS-2000 he had, to the folks that posted about the issue, to my very generous friend that replaced the filters. Hopefully the post will consolidate the info and show up in searches for folks that might have the same problem and don’t belong to the Yahoo groups where they could also find the info.