I've seen this done on another video on TH-cam and the guy said this is the recommended way that Kenwood said to clean the contacts of the relays. Looks like it worked pretty well. Cheers & 73 from W Rusty Lane K9POW in eastern Tennessee
Hi peter this great to know. Thank you for a great Video. Good catch you on 10.125 today 24/11/21 while I testing mobile.Will check this on my TS-690S. Cheers mate VK2KTG
Has anyone tried creating and installing the contact maintenance circuit as described in the same service bulletin, which is intended to mildly clean the contacts every time bands are switched? If so, what would you recommend to use instead of the now discontinued L33-0259-05 choke?
Great job Peter. I had seen this method before and have had my eye out for this radio. Just aquired one and it seems to have this problem. If I key the mic it seems to open the receive, so I think it's the same problem. Can't hurt, right. I was curious though if it would work on other radios and can't imagine why it wouldn't. Need to look into that on my Yaesu FT-840. Thanks again for the info
Despite it's age the TS-430 is great radio, just needs a bit of maintenance due to the age. You would need to study other radio circuit closely to make sure this procedure will work without causing damage.
It is a recommended Kenwood procedure with the view of using the 12v supply. Even with a reduced voltage you would need some resistance or risk damaging the relay contacts.
Could you use a 12 volt / 500 mA wall-wort? The only problem I see is that it puts out 13.5 volts for charging Purposes. Could this be used, do you think? Would the resistance be applied inside the unit its self?
13.8v will be close enough. This procedure is based on Kenwood TS-430S Service Bulletin - ASB-0902 INTERMITTENT RX. See: erikarn.github.io/kenwood/SB/ASB0902.pdf Also see: vk6ysf.com/ts-430s_maintenace_RX.htm
I don't believe this procedure accomplishes anything. Firstly, there is only 1 relay on the RF Unit board of the TS430S. When the radio is in receive mode, there is a 47k ohm resistor to ground in each of the receive filters. They all have PIN diodes, which serve the same purpose as a relay. Maybe earlier models of the TS430S used relays instead, but I don't know where they would go and there is no indication of those relays in the service manual. I suggest that anyone thinking about doing this procedure to first remove the bottom panel of their radio and take a good look at the large PCB on the underside of the radio. Mine only has one relay. I am going to replace it with the OEM relay, a Fujitsu FBR211A. Other possible causes for desense in this radio are not enough drive for RL1, incorrect PIN diode bias, and defective PIN diodes. During receive RL1 is actuated. Inadequate drive may leave the contacts separated or just barely touching. In that case there is still a signal path from the antenna connector to the input filters through a 470 ohm resistor. The AGC will take over, but not enough to overcome the desense. I have noticed that when my TS430S goes into desense on one band, it does the same on all other bands. So that would tend to rule out defective PIN diodes. I think the desense problem many see with this radio is caused by RL1 dropping out due to increased internal friction caused by age. OK, I took a closer look at the block diagram and schematics in the TS430S User Manual and see how the transmit low pass filters are also used on receive; and that is where all those relays are. However I am still not convinced this procedure accomplishes anything. There is a 100 μH inductor, L41, right next to RL1-1 on the Filter Unit. This inductor is connected to the RA pin, which goes to the antenna center pin and the other side of the inductor goes to ground. So the 500 mA just goes through that inductor, dissipating most of the power. The relays in the Filter Unit have to handle 100 Watts on transmit. If the receive contacts get dodgy so easily, why doesn't it behave worse on transmit?
I've seen this done on another video on TH-cam and the guy said this is the recommended way that Kenwood said to clean the contacts of the relays. Looks like it worked pretty well. Cheers & 73 from W Rusty Lane K9POW in eastern Tennessee
Hi peter this great to know. Thank you for a great Video. Good catch you on 10.125 today 24/11/21 while I testing mobile.Will check this on my TS-690S. Cheers mate VK2KTG
Has anyone tried creating and installing the contact maintenance circuit as described in the same service bulletin, which is intended to mildly clean the contacts every time bands are switched? If so, what would you recommend to use instead of the now discontinued L33-0259-05 choke?
Great job Peter. I had seen this method before and have had my eye out for this radio. Just aquired one and it seems to have this problem. If I key the mic it seems to open the receive, so I think it's the same problem. Can't hurt, right. I was curious though if it would work on other radios and can't imagine why it wouldn't. Need to look into that on my Yaesu FT-840. Thanks again for the info
Despite it's age the TS-430 is great radio, just needs a bit of maintenance due to the age. You would need to study other radio circuit closely to make sure this procedure will work without causing damage.
I know what I wanted to ask, why the resistor? Couldn't you reduce the amperage on a power supply and apply it directly?
It is a recommended Kenwood procedure with the view of using the 12v supply. Even with a reduced voltage you would need some resistance or risk damaging the relay contacts.
Could you use a 12 volt / 500 mA wall-wort? The only problem I see is that it puts out 13.5 volts for charging Purposes. Could this be used, do you think? Would the resistance be applied inside the unit its self?
13.8v will be close enough.
This procedure is based on Kenwood TS-430S Service Bulletin - ASB-0902 INTERMITTENT RX.
See: erikarn.github.io/kenwood/SB/ASB0902.pdf
Also see: vk6ysf.com/ts-430s_maintenace_RX.htm
Thanks 👍🇬🇧
I don't believe this procedure accomplishes anything. Firstly, there is only 1 relay on the RF Unit board of the TS430S. When the radio is in receive mode, there is a 47k ohm resistor to ground in each of the receive filters. They all have PIN diodes, which serve the same purpose as a relay. Maybe earlier models of the TS430S used relays instead, but I don't know where they would go and there is no indication of those relays in the service manual. I suggest that anyone thinking about doing this procedure to first remove the bottom panel of their radio and take a good look at the large PCB on the underside of the radio. Mine only has one relay. I am going to replace it with the OEM relay, a Fujitsu FBR211A. Other possible causes for desense in this radio are not enough drive for RL1, incorrect PIN diode bias, and defective PIN diodes. During receive RL1 is actuated. Inadequate drive may leave the contacts separated or just barely touching. In that case there is still a signal path from the antenna connector to the input filters through a 470 ohm resistor. The AGC will take over, but not enough to overcome the desense. I have noticed that when my TS430S goes into desense on one band, it does the same on all other bands. So that would tend to rule out defective PIN diodes. I think the desense problem many see with this radio is caused by RL1 dropping out due to increased internal friction caused by age.
OK, I took a closer look at the block diagram and schematics in the TS430S User Manual and see how the transmit low pass filters are also used on receive; and that is where all those relays are. However I am still not convinced this procedure accomplishes anything. There is a 100 μH inductor, L41, right next to RL1-1 on the Filter Unit. This inductor is connected to the RA pin, which goes to the antenna center pin and the other side of the inductor goes to ground. So the 500 mA just goes through that inductor, dissipating most of the power. The relays in the Filter Unit have to handle 100 Watts on transmit. If the receive contacts get dodgy so easily, why doesn't it behave worse on transmit?