Kenwood TS-430S

This is a collection of notes on the care and feeding of a TS-430S.


Common Issues

Like the TS-440S, the TS-430S suffers from a set of pretty common problems. Yes, this is kinda similar to the TS-440S notes!

Dry Joints

There are very likely dry joints everywhere. This seems to be some weird combination of perhaps some early automated soldering and a whole lot of a lack of solder being used. In a lot of cases I’ve seen barely enough solder on each pad and it cracks very very easily. A lot of repairs can be summarised as “take out each board, touch up every joint.”


The finals are either in great shape or someone’s run the rig into the ground. I always pull out the LPF output filter and finals board for inspection. I’ll always touch up the soldering on the finals board - especially around all the transistors on the board. A fresh coat of thermal grease is also a great idea.

RF Board Repair/Alignment

The RF is also pretty straight forward. The service manual goes into good detail about what to do here. The interesting thing to note is that the bandswitching control wiring to the low-pass filter board and the ACC jack passes through here. So, if you’re seeing weirdness with the LPF behaviour, I’d recommend taking a meter to the LPF related connections and see what’s going on.

PLL Board Repair/Alignment

The PLL board is relatively straight forward. If there’s the sonybond stuff on the board then you should remove it or it’ll eventually dry up and stop things from working.

Pay close attention to the TTL ICs - you need to get the right replacements in order to meet speed requirements. Eg replacing them with 74LS chips will cause the PLL to fail because it can’t keep up with the PLL loop frequency.

Control Board Repair/Alignment


USB/SSB frequency response, IF offset Alignment

Like a lot of non-computer rigs before it, the TS-430S has separate oscillators for LSB, USB and CW. AM and FM are derived from the CW oscillator.

IF offset alignment is mostly about getting the 8.83MHz oscillator working right.

FM calibration

The FM calibration does not really match what’s in the service manual. When hitting “transmit” the carrier output on Control board connector #3 doesn’t output anything! Instead, the carrier is generated and modulated directly on the FM-430 board itself.

The FM-430 board has an 8.8315MHz crystal (X1) and a trimmer capacitor (TC1) which forms the FM carrier. This is output connector #2 to the IF board - so you can check if the frequency is OK by putting an oscilloscope on Pin 1 of connector #2 (FMT, FM transmit carrier.) Assuming no modulation input, it should give a steady enough carrier to calibrate against.

TBD - figure out what TC5 is on the control board. It may also be used for AM…

Bypassing the finals for output alignment

Whilst on the topic of output alignment - here’s something I commonly do. Unless you need to test something like the finals or ALC, you can just take the RF output from the RF board, put it into a 56 ohm resistor and put a scope across that. I’ll do this for testing things like the above USB/SSB frequency response, frequency calibration, output carrier cleanliness, modulation, etc - none of these require full output power or ALC to work. It saves a bunch of headache around things around having to output real RF power just to check things - so you don’t have to worry about how long you leave your radio on and transmitting whilst aligning the VCOs/PLLs.

Using the transverter socket

The transverter socket is rather nifty on this radio. I do need to do some measurements to figure out how strong the signal gets without ALC feedback to make sure it doesn’t distort at some point.

Note that the pinout here is NOT the same as the normal 8 pin DIN layout you can find on the internet.

Here’s a snippet from the service manual - this is the pin layout on the rear socket, as if you’re looking AT the female end of the socket that you plug into.

Pin layout that the TS-430 manual uses

Here’s the pinout with a decent description.

This allows a TS-430S to be used for both HF and for transverter operation:

There are some notable limitations/gotchas!

For my initial experiments on 630m, I did the following:

I think I’ll need a 630m bandpass filter on the transverter TX output.

AM receive frequency response

One of the advantages of a general coverage receiver is the ability to listen to short-wave broadcasters from around the world on AM. The TS-430 gives a very good performance with the optional AM filter, but the bass response is poor, which is unfortunate if you are listening on a large speaker. To improve the bass response, locate the IF Unit and increase C45 (.047mF) to a l0mF tantalum then increase C57 from 0.47 mF to 2.2 mF. You can strap the new components in parallel with the existing ones. Watch the polarity on electrolytic capacitors! This modification also makes it easier to tune carriers to zero-beat against the BFO on SSB.

Broadcast band AM attenutation

Finally, there is one other source of quality AM signals, and that is the standard AM broadcast band of 540 to 1590 kHz. In my TS-430, the sensitivity dropped considerably when tuning between 500 kHz and 1600 kHz.Apart from making distant AM broadcasts inaudible, this also spoils reception of NAVTEX navigational telex transmissions on 518 kHz. The cause was the attenuator circuit in the RF unit’s 0.5-1.6 MHz bandpass filter; although the circuit says R7 should be 22W , a 220W resistor had been installed. Bridging this resistor with 27W improved the sensitivity to a very respectable level, and there is almost no change now in S-meter reading as the dial is tuned past 500 or past 1600 kHz.


This is a collection of versions of user manauls and service manuals.

High-resolution schematics