Kenwood TS-450s getting HOT

[KD2GOE]

I was having a long QSO with a friend on 12 meters and out of nowhere he tells me i stated to sounds real bad.
my SWR was good the whole time but i felt the back of the radio and it was HOT!!! i was not able to hole my hand to the back of it..
I opened it up and put a PC fan over it to cool it down.. by then my friend took off so i just let the fan cool the radio down.. i later that night fired it up and found some people talking 40m in north Dakota and Georgia the reports they gave me i was sounding good. so my conclusion was the radio got to hot and the finals went nuts.
when i key down the fans do spin. i seen a mod for the fans to come on sooner and i was wondering if any one has done this mod?

i was going to temporarily replace the Thermal censer with a pot and see at why point the fans kick on and take a reading off the pot at least i can make sure the fan controller is working.. then plug the thermal probe into my multi meter and see at what point it Resistance matches and at what temp..



http://www.mods.dk/view.php?Article...da62d1c9&i=1-kenwood-TS-450-TS450-690-fan-mod

1. Relocate the temperature sensor (thermistor ) closer to the PA transistors.
2. Lower the temperature (around 10-15 degrees C) when the fan kicks in by replacing R6 3.3K with 4.7K from the fan board X59-3370-00

To get access to PA board that includes the FAN board too you’ll need first to remove the Filter board, Carefully remove all the screws, connectors and remove the filter board. Unsolder the thermistor wires and remove extend the wires to reach the new location (closer to the RF power transistors).

Locate the FAN board and remove the R6 (3.3K), replace it with 4.7K resistor, not necessarily SMD any carbon film 1/4w would do.

Reattach all the connectors for the PA board and on top the Filter board, solder the RF connector and ground.

 

[sp5it]

I would check fan if it spins at full speed, or maybe bearings went south.
Mike

 

[KD2GOE]

I would check fan if it spins at full speed, or maybe bearings went south.
Mike

I tested the fans this morning with 12V they spin fast. with no bearing noise..

 

[2RT307]

I'd check your SWR on 12 meters again. The rigs will throttle back on power because of high SWR, and they will certainly get overheated due to high SWR.

73,
Brett

 

[KD2GOE]

I'd check your SWR on 12 meters again. The rigs will throttle back on power because of high SWR, and they will certainly get overheated due to high SWR.

73,
Brett

i was using the built in antenna tuner on the I-max 2K with my antenna analyzer 2.5:1 so it was no trouble for the tuner..

 

[KD2GOE]

It is kind of dumb of them to put the sensor all the way at the other end of the heat sink so i did the mod for the fans i all so tested then kicking on with a pot. and added some arctic silver arctic silver 5 on the drivers and finals and i used "arctic silver ceramique 2" on the pre drive because there is a non conductive shim there.. every thing else made direct contact to the heat sink so AC5 is fine...

it took 2.79k ohm for the fan to kick on before mod after i switched out the resistor 4.06k ohm for the fans to kick on..

The thermal sensor was 9.6K OHM @ room temp 22c and drops as it heats up. no way to test the curve as it heats up..
I use the hot air from my iron to test the sensor after and it did kick the fans on so ill just have to make some contacts and see if or when the fans kick on.. They where not even that loud when i tested them but they did move some air.

 

[KD2GOE]

ok so an update I just came back with a 2hr QSO with my friend on 12 meters and every thing worked out good! The back of the radio is not getting as hot and the fans kick on sooner.. What is cool with the Dual fans in the TS-450Sat there quieter then my Kenwood TS-2000..