TS-430s Poor RX Problem

Since I acquired my TS-430 a few years ago the RX on the radio has never been at its best. So in this post I will detail my solution to my TS-430s Poor RX Problem.

Background

Some bands were fine while others were very poor. After a bit of investigation I found that this could be caused by the relays in the back which do the RX / TX switching, and also switch in the various filters etc, can get dirty and create this Poor RX problem.

Poor RX Solution

Method 1: Relay Clean Kenwood Service Bulletin SB-902

When first investigating this problem one suggested solution was to apply 13.8v through a 28ohm 10W resistor to the centre pin of the antenna socket. This process is published from Kenwood with a service bulletin SB-902. I tried this process with only marginal success. This is most likely due to the lack of use. A small circuit can then be produced as a contact maintenance and can be installed in the back of the radio. This procedure is detailed here.

With this cleaning process not working for me I decided to go a step further and remove the filter board and clean the contacts manually. Then running the above process may work better.

Method 2: Relay Manual Cleaning

I started with the strip down of the back of the radio removing both top and bottom casings. I then removed the screws holding the rear panel and PA.

TS-403s - removed covers and PA

Carefully moving this out the way, this allowed access the Filter board in the back. It was at this point i took photos of all the connections to ensure they went back in the same place. WARNING, some of the RF coaxes between the final PA stage and the filter board are quite short but should just pull out of the sockets.

With this done, i removed all the connectors and the 6 screws holding the board down.

TS-403s - Removed Filter board
TS-403s Poor RX Problem -Removed Filter board

The covers to each of the relays can be removed with a thin flat head screwdriver. I then cleaned each one using some tissue paper and switch cleaner. The contacts are very small and delicate. Remember to clean both sides of the relay. I put the tissue in the open side, closed the relay onto the tissue using my finger and then put the tissue and used the spring return force of the relay to clamp the tissue. Carefully pulling the tissue out, taking care not to rip it and leaving fibres inside the relay.

Rebuild

Just reversing the process of disassembly. The board was refitted and using the images as reference, the cables were reconnected. The fiddly bit was reconnecting the short RF coaxes on the filter board.

TS-403s Poor RX Problem -Limited access

This is the small gap you have to get your fingers or tools through to then reconnect the RF coaxes.

I hope this post has helped with your TS-430s Poor RX Problem.

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