A cure for Kenwood and Yaesu Ceramic filter pandemic.

As EB5AGV wrote in his blog, there’s for some time now a true ceramic filter pandemic, worse than the H1N1 (at least for amateur radio):

http://radiorepair.blogspot.lu/2010/05/worse-than-h1n1-ceramic-filter-pandemic.html

I first read about this problem on the net while making research to open (regarding freq HI) my newly bought (at that time) TM-V71e. I first read a very well documented article to understand why and how on the SV8YM blog:

http://sv8ym.blogspot.co.uk/2010/07/mysterious-case-of-withering-filters.html

The affected rigs seems not only to be the TM-V71x but the quite similar TM-D710x and the bigger one, TS-2000 from Kenwood.  Some others manufacturers’ rigs are also victim of this pandemic. Yaesu FT-857D and FT-897 could develop the same symptoms. Because I don’t own any Yaesu rigs anymore I focused on the TM-V71e as I got two by now. My rigs didn’t develop any symptom yet but I wanted to be ready just in case.

https://www.youtube.com/watch?v=7p-7LIlpsxE

https://www.youtube.com/watch?v=fnNK-VFzzaQ

There is also some information about the serial numbers of the affected rigs but this is not really clear to me:

http://forums.radioreference.com/amateur-radio-equipment/301972-kenwood-tm-v71a-b-side-low-sensitivity.html

If you carefully read the SV8YM you’ve seen that there is a cure to the problem, but I found this solution quite complicated and risky for the RIG if made by unexperienced OM. The second link is the W2AEW YouTube video related to this solution:

http://sv8ym.blogspot.co.uk/2010/10/lift-withering-spell-off-those-ceramic.html

https://www.youtube.com/watch?v=3Y8U4BWac3w

Feeling really not comfortable with cutting trace on my TM-V71e, I began to look for something else but didn’t find anything. I then decided to develop my own board, as small as possible, to replace my (in the future) faulty filter and include the needed caps on the board, making so I won’t have to cut trace anywhere …

Later on I heard on a close French repeater a QSO between two HAM speaking from this problem, one of the fellows (F6IIX) having the problem with his rig and looking for a solution, the rig being completely useless at that time.  I broke in and proposed to give him a board ; he would just have to tell me how it works within his rig. The deal was made and I began to work on the board. I developed the board to use CMS caps and original filter’s size and made some boards.

unpopulated board

Then I look for replacement filters. The first dealer I found on the Bay was by far too expensive and I won’t make him any publicity, the sun was probably really dangerous where he lives.

You need 4 filters to repair your TM-V71x or TM-D710x, two for band A, one narrow (9 KHz) and one wide (15 KHz) and the same for band B. You can choose not to replace all filters but only the defective one, not such a good idea, believe me replace all filters at one time. The filters I’ve chosen come from a UK seller and the link are:

http://www.ebay.fr/itm/LTM455EW-15kHz-wide-455kHz-IF-ceramic-filter-replaces-ALFYM455E-CFWM455E-/252165966534?hash=item3ab6434ac6:g:6xkAAOSwPe1UGVLN

http://www.ebay.fr/itm/LTM455GW-9kHz-wide-455kHz-IF-ceramic-filter-replaces-CFWM455G-ALFYM455G-/191734198485?hash=item2ca43fb0d5

UK filter

The price was 4.01€ for each filter and I made a gentleman agreement with the dealer not to pay excessive postage, so I recommend this dealer.  I also decided to order equivalent filters but from another manufacturer to compare results. The second order were made and the price tag was 60€ for 12 filters (3 sets) inclusive postage cost, but unfortunately I can’t find back the data from this Poland based dealer. If I can find it back I will come back with the information later.

Polnish filter

You will find below two pictures from the ready to be mounted board. It’s possible to choose the position of the filter on the board, depending if you want to mount the filter upside or downside.

upside populated board     Backside populated board

I place a type AA battery to let you see the real size of the board. I give F6IIX one populated board and one unpopulated board so that he will be able to try two types of filters, just in case, not all filters are born equal.

 

The second part of this article is related to the insertion of the board in the F6IIX rig. Pictures by F6IIX.

Rigs before modifications, components side.TMD710 platine support filtres blog

Rigs before modifications, trace side.TMD710 platine support filtre coté soudures blog

Filter removed and dismantled, you can clearly see the oxydation into the filters.TMD710 filtres démontés vue sur oxydation blog

All the four filters removed and the wire solded in place. (F6IIX choose to solder an earth ground wire for each filter, the blue ones . This is good practice but if you have trouble doing the job, you can use only one ground connection, all ground are connected to each other on the filter board. Using four ground wires gives also more stability if the wire are also used as support for the board).TMD710 filtres retirés blog

The filter board in place and connected. Filters are mounted on the hidden face. (You can put some double sided foam tape between the Kenwood board and the filters board for even more stability, your choice.)TMD710 platine montée blog

F6IIX comments.
I didn’t notice any problems after the modification, even at full output power.
To take the filters apart, I use a plier to open the filter; I then take the ceramics inserts away. Then I heat each remaining filters legs with a soldering iron and pull the legs out. Each wire (0.3 mm isolated) has been inserted and soldered with XYL help. I soldered all ground wires. The board is self-maintained using short wire making some traction on the filters board.
The pictures clearly explain the process and if you take your time, they will be no problem doing the job.
It takes me two evenings and one afternoon to complete the task.

(F6IIX didn’t own a desoldering station at the time of the modification. He now own one making the task much easier next time HI. I think I will need one hour for the job using my desoldering station.
Thanks to Jean-Marie F6IIX beeing a crash test dummie)

Regards Stephan.
LX2SM / LX2OOO

Comments welcome.

3 thoughts on “A cure for Kenwood and Yaesu Ceramic filter pandemic.

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