Cleaning ts430s lpf relays

[VA6AW]

I have a service bulletin from kenwood from 1985 that says i should run 13 vdc into the antenna terminal through two 56 ohm 5 watt resistors in parallel. They indicate that 500 ma of current will clean the relays if i cycle thru each filter relay with the up (1 mhz) control.

My question, as im gettin to old to remember my basic electronics, do i have to use a current limiting power supply to keep the current at 500ma. Dont want to smoke the thing.

Gary

[K8ERV]

No, that is what the resistors do. George Simon says that 13v thru 28 ohms provides the .4642857 amps, exactly what is needed.

TOM K8ERV Montrose Colo

[VA6AW]

Tnx tom

thats what i figured but never know. Now just need to find some resistors and hope it works as planned.

This 430 receives some bands but others are completely dead except some birdies.

Gary

[ai3v]

This will work for a while, but the permenent fix would be to find some relays that have "dry" contacts- usually gold plated-.

Inexpensive relays, switches and contacts that are not rated "dry" require a small voltage to break down the oxidised layer that forms on the contact, The tiny received signal isn't enough to "punch thru" the insulating oxide layer.

Rege

[VA6AW]

Tnx rege

there is another bulletin that gives a small circuit with a resistor, choke and some caps that will supply 8v at low current to these relays after the relays are cleaned by the 13 v dc setup.

It states that this should keep the relays clean whenever the lpf filter changes relays. Hope that works to.

Dont want to start changing relays if i can help it. This 430 is so small its hard to get at these areas hi.

Anyway thanks for the help fellows.

Gary va6aw

[WT9S]

Gary,

I performed that procedure about a month ago on mine. It took several applications of the DC voltage to burn all the crud off of my relay contacts. The procedure, IIRC, says to apply it for one minute while holding down the up or down band button (1 MHz switch on). After trying that twice I did it for 8 or 9 minutes and finally got them clean. I added the maintenance circuit a couple of weeks later and all still seems to be well.

[VA6AW]

Sound like im on the right track, tnx guys. Just have to find the resistors as dont have a junk box anymore. Just getting back on the air after about 30 year absence.

Called my friend who works with audio power amps etc and he may have some. Kind of hard to find these parts here as everything nowadays is digital. No need for big power resistors anymore.

Gary

[ai3v]

Hi Gary,

The mod to apply a bit of bias will be the ticket!

Rege

[WT9S]

I got them from Mouser, along with everything needed for the maintenance circuit, including the terminal strip. I think it was about $16 with a few extra parts too.

[K8ERV]

If you don't find one, sure I can find a 50 or 60 ohm resistor that will work, and will send free.

TOM K8ERV Montrose Colo

[VA6AW]

Tom k8erv

that would be great if you have any. Circuit says two 5 watt resistors but a 10 watt would do fine.

The friend i mentioned makes molasses in winter look fast if he has to look for something.

Will also check out mouser. Tnx jay (wt9s)

on a fixed income, spend half on the radio and rest on rent hi, so may have to wait till payday to get the other parts. But one step at a time.

Some other mods i am going to do are the am audio (terrible), noise blanker, the lpf relay problem and anything else i can find that might help make this thing better.

Anyway all the help and suggestions have been a great help. Qrz saves the day once again hi.

Gary

[VA6AW]

I case anyone still reading this post i have provided some new life to the ts430.

Got 2 86 ohm 5 watt resistors and ran the 13 vdc thru the relays. Cycled for 1 minute, then 30 seconds off and cycled again on and off for about 10 minutes.

Now have an s meter reading hi. Will see how it goes but so far so good. Just need to get the parts for the maintenance circuit and should be in business.

Gary

[WA3RA]

I wish I could use that trick on my TS-830. I have to pull the relay and do it the hard way.:p